Chitosan-Reinforced Carbon Aerogels from Oil Palm Fronds for Enhanced Oil Absorption and Silver Nanowires Loaded as Antimicrobial Activity

Chitosan-Reinforced Carbon Aerogels from Oil Palm Fronds for Enhanced Oil Absorption and Silver Nanowires Loaded as Antimicrobial Activity | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Chitosan-Reinforced Carbon Aerogels from Oil Palm Fronds for Enhanced Oil Absorption and Silver Nanowires Loaded as Antimicrobial Activity Bernadeta Ayu Widyaningrum, - Sudarmanto, Lu’lu ’ Qurrotul ‘Ain Hariri, and 8 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7269305/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 19 Oct, 2025 Read the published version in Journal of Porous Materials → Version 1 posted 17 You are reading this latest preprint version Abstract This study explores the development of carbon aerogels (CA) derived from oil palm fronds (OPF) with chitosan (CS) reinforcement and silver nanowires (AgNWs) incorporation for oil absorption and antimicrobial applications. Cellulose nanofibrils (CNF) were extracted from OPF and mixed with CS in varying mass ratios (2:1, 1:1, 1:2, and 1:3) before undergoing freeze-drying and carbonization at temperatures of 300 o C. The resulting carbon aerogels were further functionalized with AgNWs using a dip-coating technique. The CA samples were characterized for their density, porosity, surface area, and wettability. The absorption capacity for marine fuel oil, palm oil, and high-speed diesel oil ranged from 20–76 g/g, influenced by the aerogel’s pore structure. The addition of CS improved the aerogel’s structural integrity, enhancing reusability over multiple absorption-desorption cycles. AgNWs loading imparted strong antimicrobial activity, particularly against Gram-negative bacteria ( E. coli and S. typhi ), as demonstrated by the agar diffusion method. The results suggest that CA-AgNWs composites exhibit excellent oil absorption performance, selectivity, and reusability, along with broad-spectrum antimicrobial properties. These findings highlight the potential of OPF-derived carbon aerogels as multifunctional materials for environmental and medical applications. This research demonstrates a sustainable approach to utilizing biomass waste for creating high-performance absorbents with tailored properties. Future work may focus on optimizing the composition and processing conditions for enhanced application efficiency. Carbon aerogel Oil palm fronds Chitosan Silver nanowires (AgNWs) Antimicrobial activity Oil absorption Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 1. Introduction Environmental and ecological issues arising from crude oil spills, petroleum products, and toxic organic solvents present significant challenges that demand immediate attention. Annually, numerous incidents of oil spills occur in marine environments, leading to severe damage to wildlife habitats, economic disruption, and health hazards to humans. Various methods, including physical diffusion, biological and chemical treatments, in situ burning, and biodegradation, have been employed to mitigate these environmental impacts [ 1 ]. However, absorption stands out as an effective, cost-efficient, and environmentally friendly method for oil spill remediation. The development of ideal absorbent materials requires a combination of high absorption capacity, selectivity, reusability, and eco-friendliness. Carbon aerogels (CA) have garnered attention due to their porous, three-dimensional (3D) interconnected networks, which exhibit unique wetting properties suitable for effective oil/water separation [ 2 ]. The 3D structure of CA, coupled with properties such as low density, high porosity, large specific surface area, and hydrophobicity, enhances their absorption capacity and selectivity for oils and organic solvents [ 2 – 6 ] The open porous network of CA allows for efficient molecular access and penetration into their inner structures [ 2 ]. Recently, the use of biomass as a precursor for carbon-based materials has gained increasing interest due to its cost-effectiveness, abundance, sustainability, and ease of procurement [ 2 , 3 , 7 – 9 ]. Several studies have reported the fabrication of cellulose-based carbon aerogels from various biomass sources [ 10 ], such as winter melon melon [ 3 ], cotton [ 11 ], poplar catkin [ 9 ], straw [ 12 ], bamboo [ 13 ] and softwood kraft [ 14 ]. Indonesia, with its vast palm oil plantations, produces a considerable amount of oil palm fronds (OPF), which are often underutilized and considered waste. Given that OPF contains significant amounts of α-cellulose, hemicellulose, and lignin [ 15 ], it presents an excellent source for creating carbon aerogels for oil/water absorption applications. However, traditional carbon aerogels have limitation especially in their reusability because their structure is very brittle. To address the limitations of conventional oil absorbent materials, researchers have explored the fabrication of carbon aerogel composites using various organic and inorganic fillers. Chitosan, a natural polysaccharide, has gained significant attention as a reinforcing filler in carbon aerogels due to its mechanical strengthening capabilities and biocompatibility. Studies have shown that integrating chitosan into the aerogel matrix improves the mechanical stability of the material, mitigating brittleness and enhancing reusability [ 16 ]. The layered sheets formed by chitosan provide a connective framework within the aerogel, thereby increasing its toughness and durability [ 17 ]. Silver nanowires (AgNWs) is one of antimicrobial agents with unique structure. Silver ions possess antibacterial properties that can inhibit protein activity and DNA replication in bacterial cells [ 18 ]. Furthermore, several studies have acknowledged their properties in mitigating biofouling cells [ 18 ]. It gives great prospects to combine AgNWs onto CA structure to create advanced absorbent materials that meet the demands of environmental cleanup operations. Herein, a 3D structure of CA with AgNWs loading (CA-AgNWs) has been successfully fabricated from OPF using a freeze-drying method and low carbonization temperature, making it more energy-efficient and environmentally friendly. In addition, the CA-AgNWs exhibited good adsorption capacity for various oils reached up to 72 times its weight and can maintain its structure after 36 cycles by squeezing. The AgNWs loading into CA shows well-dispersed and antimicrobial activity. The findings of this research are expected to contribute to the development of more efficient, sustainable, and multifunctional absorbent materials for environmental cleanup operations, particularly in the context of oil spill remediation. 2. Materials and Methods 2.1. Materials The primary materials used in this study include oil palm fronds (OPF) waste, technical chitosan (CS) derived from shrimp with a deacetylation degree of less than 90%, acetic acid (CH 3 COOH, Merck, Singapore), silver nitrate (AgNO 3 , Merck, Germany), ethylene glycol (EG, Merck, Singapore), polyvinylpyrrolidone (PVP, Sigma, Singapore), iron (III) chloride hexahydrate (FeCl 3 ·6H 2 O, Merck, Singapore), and acetone (Merck, Singapore). Nutrient agar and nutrient broth were purchased from Himedia, in Indonesia. Deionized water, used throughout the study was sourced from a local supplier to ensure consistent quality. 2.2. Extraction of biomass cellulose Oil palm fronds (OPF) were sourced from the Research Centre for Biomass and Bioproduct - BRIN, Cibinong. The fronds were initially chopped and sieved to a 60-mesh size to standardize the particle dimensions. To remove impurities, the sieved biomass was washed thoroughly in water and ethanol three times. This washing process ensured the elimination of surface contaminants and unwanted organic substances. The delignification of the OPF was conducted using a sodium hydroxide (NaOH) solution at a concentration of 9% w/v. The delignification process was carried out in a heated reactor at 170 o C for 1 hour. After this treatment, the pulp was thoroughly washed with deionized water until the pH reached a neutral level. The washed pulp was then dried in an oven at 60 o C for 24 hours. The dried pulp is then stored for further processing. 2.3. Preparation of cellulose nanofibril (CNF) The dried cellulose pulp obtained from the oil palm fronds (OPF) was first soaked in deionized water for 24 hours to facilitate hydration and soften the fibers. The hydrated pulp was then processed using a Masuko Sangyo Supermass colloider grinder (MKCA6-3; Masuko Sangyo Co., Ltd.) to produce cellulose nanofibrils (CNF). The defibrillation process was carried out at a concentration of 1.0 wt% cellulose. The grinding was conducted over five cycles at a rotation speed of 1500 rpm, with the gap between the stone plates gradually adjusted to optimize fibrillation. The resulting CNF suspension exhibited a gel-like consistency, indicating the successful breakdown of the cellulose fibers into nanoscale fibrils. This CNF served as a key structural component in the fabrication of the carbon aerogel (CA). 2.4. Synthesis of the AgNWs The silver nanowires (AgNWs) were synthesized using a modified solvothermal method based on the procedure outlined in our previous work [ 19 ]. The synthesis was conducted in a Teflon-lined autoclave to ensure a controlled reaction environment. Initially, an ethylene glycol (EG) solution containing 0.1 M silver nitrate (AgNO 3 ) was prepared and poured into the reactor. The mixture was heated under stirring until the temperature reached 170 o C, allowing the AgNO 3 to dissolve completely. Following this, an EG solution containing 0.1 mM iron (III) chloride (FeCl 3 ) and 0.417 g of polyvinylpyrrolidone (PVP) was introduced into the autoclave using a syringe to ensure a gradual addition. The mixture was then heated for 2.5 hours under isolated conditions to promote the growth of AgNWs. The resultant solution was subjected to sonication to ensure the complete dispersion of AgNWs. It was then rinsed three times with acetone to remove any unreacted precursors and excess PVP. The final solid product, AgNWs, was collected and stored for further use. 2.5. Fabrication of carbon aerogel (CAn) The fabrication of carbon aerogels (CAn) involved the preparation of cellulose-based aerogels with chitosan (CS) as a reinforcing filler. The process began with preparing a mixture containing 1% cellulose nanofibril (CNF) and 2% chitosan dissolved in 1% acetic acid solution. Different mass ratios of CNF to CS (n = 2:1, 1:1, 1:2, and 1:3) were prepared to investigate the effect of varying filler content on the properties of the aerogel. Each mixture was stirred thoroughly to ensure homogeneity, followed by pouring into mold containers. The mixtures were then cooled at -20 o C for 24 hours and continue to dry using freeze-dryer, which resulted in lightweight, porous aerogels. Subsequently, the aerogels were subjected to a carbonization process to convert them into carbon aerogels. The aerogels were placed in a tube furnace under a nitrogen atmosphere and heated to the target temperatures of 300 o C. The temperature was increased at a rate of 10°C per minute and maintained at the target temperature for 2 hours. The nitrogen atmosphere was maintained throughout the carbonization process to prevent oxidation. The specific sample codes for each carbon aerogel are listed in Table 1 . Table 1 Sample codes of carbon aerogels (CAn) Sample Code Mass Ratio CNF to CS (n) CA1 2:1 CA2 1:1 CA3 1:2 CA4 1:3 2.6. AgNWs loading into CAn-X The incorporation of AgNWs into the CA was performed using a dip-coating technique to ensure an even distribution of AgNWs on the aerogel surface. Initially, AgNWs were dispersed in acetone at various concentrations (X = 0.5%, 1%, 2%, 5%, and 7%) and then subjected to sonication for 30 minutes. This sonication step helped to break up any agglomerates and achieve a uniform suspension of AgNWs, facilitating their effective loading onto the aerogels. After dipping, the aerogels were quickly dried in an oven at 105 o C for 5 minutes to evaporate the acetone and fix the AgNWs onto the surface. 2.7. Characterization The characterization of the CNF, CAn, and CAn-X was conducted using various analytical techniques to understand their structural, morphological, and functional properties. The morphology of the CNF was observed using a Transmission Electron Microscope (TEM, Tecnai G2 20S-Twin). The TEM analysis provided information on the size and fibrillation degree of the CNF, confirming the nanoscale dimensions. The macrostructure of the CAn-x aerogels and the distribution of AgNWs were examined using a Field Emission Scanning Electron Microscope (FESEM, Thermo Scientific Quattro S). The functional groups were analyzed using Fourier Transform Infrared Spectroscopy (FTIR, ATR-Perkin Elmer). FTIR spectra were recorded in the range of 4000 to 500 cm − 1 to identify the chemical bonds and functional groups. The Brunauer–Emmett–Teller (BET, Quantachrome Nova 4200e) with BJH method was used to evaluate the surface area and pore structure. The hydrophobic properties of the were assessed using a digital microscope (Dino-Lite). Water contact angles (WCA) were measured to evaluate the surface wettability and hydrophobicity of the aerogels, which directly influence their oil absorption selectivity. 2.8. Density and porosity The density ( ρ ) of the CAn was determined by measuring their mass and volume, in this measurement we use triple replication. The mass was obtained using a precision analytical balance, and the volume was calculated based on the dimensions (height and diameter) of the cylindrical aerogel samples. The density was then calculated using Eq. ( 1 ): $$\:\rho\:=\frac{m}{v}$$ 1 where m represents the mass of the carbon aerogel and v is the volume. The porosity ( P ) of the carbon aerogels was assessed using Eq. ( 2 ): $$\:P=\left(1-\frac{\rho\:}{{\rho\:}_{s}}\right)\times\:100$$ 2 where ρ is the density of the carbon aerogel obtained from Eq. ( 1 ), and ρ s is the density of the solid material. The solid material density ρ s was assumed based on the theoretical density of carbon, given the carbonization of the cellulose and chitosan components. 2.9. Absorption capacity and reusability The absorption capacity ( C ) of the carbon aerogels (CAn) was evaluated using three different types of oils: marine fuel oil (MFO), palm oil (PO), and high-speed diesel oil (HSD). To conduct the absorption test, each sample was weighed before and after immersion in the oil with triple replicates, allowing the calculation of absorption capacity using Eq. ( 3 ): $$\:C=\frac{\left(m-{m}_{0}\right)}{{m}_{0}}$$ 3 where C is the absorption capacity (g/g), m 0 is the initial weight of the dry sample, and m is the weight of the samples after oil absorption. The samples were fully immersed in oil for a specified time to ensure saturation. After immersion, the samples were removed, excess surface oil was carefully blotted off, and the final weight was recorded. Each absorption test was repeated three times, and the average value was used to ensure the accuracy of the results. The reusability of the CAn was determined by conducting cyclic squeezing tests. After absorption, the aerogels were compressed using a piston pump to 40% of their original height to expel the absorbed oil. After squeezing, the samples were immediately immersed back into the oil for the next absorption cycles. This process was repeated until the CA showed signs of structural damage or collapse, which marked the end of its reusability. The number of successful absorption-desorption cycles before damage was recorded as the aerogel’s reusability metric. The absorption capacity and reusability tests provided valuable data on the aerogels’ oil absorption performance and durability. For each experiment absorption capacity and reusability, we use triple replicates. 2.10. Antibacterial test The antibacterial activity of the CAn-X was assessed using the agar diffusion method. The plates were incubated at 37°C for 24 hours to allow bacterial growth and diffusion of the antimicrobial agent from the samples into the surrounding agar medium. Following incubation, the antimicrobial activity was determined by measuring the diameter of the clear inhibitory zones formed around each CAn-X. These zones indicated the area where bacterial growth was inhibited due to the antimicrobial effect of the AgNWs on the samples. The average diameter of the inhibition zones for each bacterial strain was recorded to quantify the antibacterial performance of the samples. This test was performed to evaluate the antimicrobial effectiveness of the CAn-X against both Gram-positive and Gram-negative bacteria. The bacterial strains used in this study were Staphylococcus aureus (Gram-positive), Salmonella typhi , and Escherichia coli (both Gram-negative). 2.11. Statistical Analysis of Carbon Aerogel (CAn-X) The data obtained from the experiments, including the measurements of density, porosity, absorption capacity, reusability of the CAn, and antibacterial activity of CAn-X, were statistically analyzed using STAR (Statistical Tool for Agricultural Research) software version 2.0.1, developed by the International Rice Research Institute. The statistical analysis aimed to determine the influence of different treatments on the properties of the CA. A single-factor completely randomized design (CRD) was used in this study, ensuring that all treatment conditions were replicated a minimum of three times for accuracy. The effects of varying mass ratios of cellulose nanofibrils (CNF) to CS and AgNWs loading were assessed using one-way analysis of variance (ANOVA). This analysis identified the significance of individual and interactive effects of the variables on the aerogel properties. When the ANOVA results indicated significant differences (p < 0.05) among the treatments, Duncan’s Multiple Range Test (DMRT) was employed to compare the means and ascertain the specific treatments that differed significantly. This statistical approach ensured a comprehensive understanding of how each factor contributed to the physical, chemical, and functional characteristics of the CAn-X. 3. Results and Discussion 3.1. Preparation and characterization of CAn The preparation and characterization of the CAn composites were fabricated by a series of steps of defibrillation, freeze-drying, and carbonization as illustrated in Figure 1(a) . At the first step cellulose nanofibers (CNF) were extracted from oil palm fronds (OPF) via a mechanical process. The transmission electron microscope (TEM) images of CNF shown in Figure 1(b) , revealed a single round and long fiber, and the high magnification TEM image ( Figure 1(c) ) shows the single cellulose has a diameter ranging between 10 and 47 nm, indicating successful fibrillation of the cellulose nanofibers. Cellulose as natural resources were chosen due to high polymerization, chemical durability, and mechanical stability. These properties are attributed to the strong intermolecular hydrogen bonds, which facilitate the formation of interconnected three-dimensional (3D) network structures [20]. The next step was fabrication of OPF aerogels. This step was subsequently prepared by mixing CNF and chitosan (CS) in various mass ratios, followed by a freeze-drying process to form a porous structure. Field Emission Scanning Electron Microscopy (FESEM) images in Figure 2 demonstrate the morphology of the aerogel. FESEM showed that aerogel had an irregular, rough, and slightly porous surface in the axial direction, while the radial direction appears smoother and more layered. These morphological features suggest that the aerogel structure is suitable to form a carbon network upon carbonization. The OPF aerogels were then subjected to thermal treatment through a carbonization process at temperatures of 300 o C to convert into carbon aerogels. During carbonization, the main chains of CNF and CS underwent chemical reactions to build a robust carbon framework without degradation of their primary structures. Compared to the initial aerogel structure, the resulting carbon aerogels of different carbon aerogels (CA1 to CA4) displayed a flaky macrostructure with noticeable volume shrinkage, as depicted in Figure 3 . The morphologies of these samples varied slightly different. CA1 and CA2 exhibiting significantly higher porosity and layered porous structure compared to CA3 and CA4. The porosity of the CA created a pathway for oil transport, while the bridges formed between the layers contributed to the integrity of the structure [21,22]. This observation aligns with the porosity measurements, suggesting that higher specific surface area and porosity lead to improved adsorption capacity. In addition, carbonization can cause mass loss, Table 2 outlines the mass loss of CA during carbonization at 300 o C with ranging from 51% to 66%. The mass loss during carbonization was influenced by composition of the aerogel. This supported by statistical analysis, the mass ratio of CNF to CS significantly influenced the ex-tent of mass loss. This result is consistent with previous studies, which report that higher carbonization temperatures tend to increase mass loss due to the volatilization of organic components and the erosion of the carbon framework [23,24]. The findings of this study indicate that the structural properties of carbon aerogels (CAn) derived from oil palm fronds (OPF) can be tailored by adjusting the carbonization temperature and the ratio of cellulose nanofibers (CNF) to chitosan (CS). As shown in Table 2 , the mass loss during carbonization was influenced by the composition of the aerogel [23,24]. Table 2. Mass loss of CA after carbonization at temperature 300 o C (Values in column having different letters in superscripts showed significant difference (p<0.05)) Sample Code Before (g) After (g) Mass loss (g) % CA1 0.198±0.001 0.089±0.001 0.109 b 55.11 CA2 0.235±0.005 0.114±0.003 0.12 a 51.29 CA3 0.224±0.009 0.110±0.001 0.114 ab 51.02 CA4 0.241±0.003 0.119±0.007 0.122 a 50.57 Compared to other biomass-derived carbon aerogels, the carbon aerogels synthesized in this study demonstrate distinctive properties. For example, carbon aerogels derived from materials such as winter melon, cotton, and bamboo have shown a tendency to become brittle after carbonization, particularly at higher temperatures [2,3,8–10,23]. The incorporation of chitosan into the OPF-derived aerogels in this study, however, provided structural reinforcement, as evidenced by the SEM images in Figure 3 . The layered sheets formed by chitosan within the aerogel matrix enhanced the mechanical strength and reduced the brittleness of the carbon aerogels. This finding aligns with the work of [26], which demonstrated that chitosan could act as a reinforcing agent to improve the mechanical performance of carbon-based materials. From a scientific perspective, this research contributes to the body of knowledge on the fabrication of biomass-derived carbon aerogels. The incorporation of chitosan into the carbon aerogel matrix was found to play a crucial role in improving the mechanical properties, particularly in mitigating brittleness. At 300 o C, the aerogels maintain a porous, interconnected structure, facilitating oil transport and retention. This finding is in line with earlier studies that emphasize the importance of porosity and specific surface area in enhancing adsorption capacities [25,26]. The successful fabrication of OPF-derived carbon aerogels with enhanced mechanical properties and adsorption capacity suggests that these materials can be deployed in oil/water separation applications. Their robust structure, resulting from the inclusion of chitosan, ensures that the aerogels can endure multiple cycles of oil absorption and recovery, improving their sustainability and cost-effectiveness in real-world scenarios. Additionally, the use of OPF as a raw material aligns with the principles of waste valorization, promoting a circular economy approach by converting agricultural waste into valuable functional products. 3.2. Density, porosity and surface area of CAn The density, porosity, and surface area of the CAn were determined to evaluate how variations in chitosan content affect their structural properties. Table 3 presents the density and porosity values of CAn under different mass ratio of CS. A notable linear increase in density was observed with the increase in chitosan content, while a simultaneous decrease in porosity occurred. The statistical analysis conducted in this study also provides valuable insights. The finding that the porosity of CAn was primarily influenced by the ratio of CNF to chitosan, with an increase in chitosan resulting in a lower density. In contrast, the density becomes higher when affected by the CNF-chitosan ratio. This suggests that chitosan (CS) not only acts as a filler but also enhances the interaction between cellulose nanofibers (CNF), maintaining the integrity of the porous structure and making it more compressible [26]. Similar report has been reported by Zhang et al. (2021a), in their study, the addition of CS significantly enhanced the mechanical integrity of cellulose-based aerogels, resulting in a denser and more compact structure. This conclusion is consistent with the work of Han et al. (2016) and Jing et al. (2019), who emphasized the interplay between carbonization temperature, structural integrity, and adsorption capacity [25,27]. The carbonization at 300 o C showed more developed carbon structure, albeit with varying degrees of mass loss and brittleness and with promising the material’s structural integrity, as seen in Figure 4 . The results of the Brunauer-Emmett-Teller (BET) analysis, detailed in Table 4 , further elucidate the impact of carbonization temperature on the surface area, pore size, and pore volume of CAn. The opening of pores at elevated temperatures, which increases the available pore volume and surface area. However, this effect comes at the cost of damaging the carbon aerogel’s structure, as high temperatures can lead to structural erosion [28]. Carbonization at 300 o C resulted in aerogels with a favorable balance between porosity, surface area, and mechanical stability. The results support the notion that an optimal carbonization temperature can enhance the adsorption capacity of the aerogels without compromising their structural integrity [25,28]. Congsomjit and Areeprasert (2021), also reported that elevated temperatures facilitate pore opening, thereby enhancing the surface area and pore volume. From Table 4, it shown that control samples exhibited higher values for surface area, pore size, and pore volume but these values declined upon the addition of chitosan. The addition of chitosan altered the pore size distribution of the aerogels from mesoporous (control) to microporous. Despite this modification, variations in the mass ratio of the composition did not significantly affect the resulting pore diameter. Chitosan appears to graft onto the inner open pores, thereby reducing the specific surface area, total pore volume, and mesopore volume while preserving the monolithic integrity of the carbon material. The pores’ configuration facilitates oil storage and further promotes oil transport through the aerogel. When compared to other biomass-derived carbon aerogels, such as bamboo and cotton, for instance, exhibited high surface areas but suffered from reduced reusability due to structural brittleness [11,13,29]. In contrast, the CAn samples in this study, particularly those carbonized at 300 o C, showed a favorable balance between surface area, pore size, and mechanical strength, largely attributed to the reinforcing effect of chitosan. Table 3. Density and porosity of CAn (Values in columns with different letters in superscripts indicate significant differences, p < 0.05) Sample Code Density (g/cm 3 ) Porosity (%) Control 0.0129±0.003 97.07±0.07 a CA1 0.0134±0.001 97.34±0.16 a CA2 0.0181±0.001 93.88±0.35 b CA3 0.0230±0.004 92.78±0.55 c CA4 0.0318±0.011 92.07±0.95 c Table 4. Surface area, pore size, and total pore volume of CAn at carbonization temperatures of 300 o C Sample code Surface Area (m 2 /g) Pore size (nm) Total pore volume (cm 3 /g) Control 107.8 21.68 0.630 CA1 60.31 2.185 0.378 CA2 53.18 1.723 0.367 CA3 47.50 1.745 0.355 CA4 43.92 1.736 0.226 3.3. FTIR analysis Fourier-transform infrared (FTIR) spectroscopy was employed to identify the characteristic peaks of functional groups in cellulose nanofibers (CNF), chitosan (CS), aerogel, and CAn. The FTIR spectra, as presented in Figure 5 , exhibit distinct peaks corresponding to various chemical bonds and functional groups present in the samples. In the CNF spectra, key bands were observed at around 1160 cm -1 , 1611 cm -1 , and 3298 cm -1 , representing C–O bond vibrations, COOH bending, and O–H stretching, respectively. Additional peaks at 1375 cm -1 , 1427 cm -1 , and 2896 cm -1 correspond to the C–H bending mode and characteristic C–H stretching of the CH 2 group, which are typical of cellulose [29,30]. For chitosan, the characteristic peaks associated with amide functional groups appeared at 1650 cm -1 (amide I), 1590 cm -1 (amide II), and 1317 cm -1 (amide III) [31,32]. When comparing the FTIR spectra of chitosan and CNF with that of the aerogel, a co-existence of peaks was evident, signifying the integration of both components within the aerogel structure. Specifically, the aerogel spectrum exhibited N–H banding at 1638 cm -1 and 1414 cm -1 , as well as O–H peaks at 3298 cm -1 , 2896 cm -1 , and 1020 cm -1 . Additionally, a prominent C–H asymmetric stretching peak was detected at 2910 cm -1 [27,33], confirming the successful formation of a composite network between chitosan and CNF. This bonding network is crucial for maintaining the aerogel’s structure during carbonization, thereby facilitating the development of a stable, porous material suitable for oil absorption. Notably, after carbonization, the O–H stretching vibrations at 3410 cm -1 were significantly diminished, likely due to dehydration reactions occurring during the thermal treatment. This observation aligns with the expected chemical changes associated with carbonization. Additional peaks at 1595 cm -1 and 1365 cm -1 , corresponding to C=C vibrations of aromatic rings, were identified in the carbon aerogel spectra. These peaks suggest the formation of aromatic structures resulting from dehydrogenation and aromatization during carbonization [25,34,35]. Furthermore, bands within the 650–800 cm -1 range were attributed to the out-of-plane bending vibrations of unsaturated C–H, indicative of the presence of aromatic compounds in the carbonized samples. This observation is consistent with the formation of a more stable aromatic carbon structure, which contributes to the aerogels’ improved oil absorption properties. In comparison with studies on other biomass-derived carbon aerogels, the CAn samples in this research exhibited more pronounced aromatic characteristics, suggesting a more extensive dehydrogenation process during carbonization. This characteristic is vital for oil absorption applications, as aromatic structures enhance the hydrophobicity and oil-selective properties of the aerogels [25,34]. This finding contrasts with other studies that utilized different biomass sources, where the incorporation of additional components did not always result in clear, distinct peaks corresponding to the composite materials. For instance, in carbon aerogels derived from sugarcane bagasse, Li et al. (2021a) observed less distinct peak formations due to the complexity of the biomass source [29]. The FTIR analysis reveals that the carbonization process not only removes surface hydroxyl groups but also induces structural changes that result in the formation of aromatic compounds. This transformation is critical in enhancing the carbon aerogels’ absorption capacity. In practical terms, these findings highlight the potential of OPF-derived carbon aerogels as environmentally friendly and efficient oil absorbents. The formation of aromatic structures within the aerogels, as evidenced by the FTIR analysis, contributes to their hydrophobic nature, which is essential for selective oil absorption in oil/water separation applications. The ability to fine-tune the carbonization temperature to control the aerogels’ surface characteristics further emphasizes the versatility of this material for various environmental remediation purposes. Moreover, the use of OPF as the primary biomass source aligns with the principles of waste valorization and sustainability. By converting agricultural waste into functional carbon aerogels, this study provides an eco-friendly approach to mitigating oil pollution. 3.4. Wettability and selectivity of CAn The adsorption performance of CAn is closely linked to their hydrophobic and oleophilic properties. To evaluate the wettability of the different CAn samples, water contact angle (WCA) measurements were conducted. As shown in Figure 6(a) , CAn demonstrates excellent hydrophobicity, allowing water droplets to remain on the surface without spreading. This behavior indicates that the surface of CAn effectively repels water, a characteristic essential for oil/water separation applications. To further investigate the effect of composition on hydrophobicity, the WCA results for each sample are presented in Table 5 . The WCA values for CAn samples were found to be greater than 150°, confirming their superhydrophobic properties. According to studies by Jing et al. (2019), Y. Q. Li et al. (2014), and T. Zhang et al. (2019), carbonization induces dehydration reactions that remove water molecules from the aerogel structure, enhancing its hydrophobic properties [3,8,26]. The addition of CS significantly increased the WCAs, indicating enhanced hydrophobicity. This finding diverges from the results of some earlier research, where the inclusion of fillers into carbon-based materials did not markedly alter surface hydrophobicity [28]. The increase in WCA with higher CS content in may be attributed to chitosan’s ability to fill the voids in the aerogel matrix, thereby creating a denser structure during carbonization. This denser structure contributes to the material’s superhydrophobic properties by preventing water molecules from permeating the surface. Additionally, the selectivity of CAn towards oil and water was observed in Figure 6(b) . The figure illustrates that water droplets are repelled and stand on the aerogel’s surface, whereas oil droplets penetrate the structure, signifying the aerogel’s oleophilic nature. This selectivity is crucial for the aerogel’s application as an oil absorbent, as it enhances the efficiency of oil uptake while minimizing water absorption. Table 5. Water contact angles (WCA) of CAn at carbonization temperatures of 300 o C Sample code 300 o C ( o ) Control 175.29±1.04 CA1 176.42±1.27 CA2 176.56±1.15 CA3 176.68±0.12 CA4 178.30±1.11 The wettability and selectivity analysis highlight that the CS content significantly influence the hydrophobic and oleophilic properties of CAn. The results demonstrate that increasing the CS mass ratio leads to higher WCAs, enhancing the material’s superhydrophobicity. This characteristic, combined with the aerogels’ selectivity for oil over water, positions CAn as a promising candidate for oil spill cleanup applications. 3.5. Absorption capacity and reusability The absorption capacity and reusability of CAn were assessed using various oils, including marine fuel oil (MFO), palm oil (PO), and high-speed diesel oil (HSD). The results are summarized in Table 6 , showing that the absorption capacity of CAn between 20–76 g/g, depending on the oil type (density and viscosity) and the pore structure of the aerogel. The superhydrophobic nature of CAn, along with its interconnected porous network, facilitated oil absorption, confirming its potential for oil spill remediation. The control samples of CAn in this study exhibited the highest absorption capacities for marine fuel oil (MFO), palm oil (PO), and high-speed diesel oil (HSD) (76.27 ± 1.05 g/g, 72.31 ± 1.97 g/g, and 55.70 ± 1.56 g/g, respectively). This observation can be attributed to the larger pore sizes and volumes of the control samples, as shown in Table 4 , which facilitate the storage and transport of oil. When compared to other carbon aerogels derived from various biomass sources, the CAn exhibit competitive absorption capacities. For instance, carbon aerogels made from sugarcane bagasse, as studied by Li et al. (2021a), showed absorption capacities in a similar range [29]. In contrast, aerogels with higher CS content demonstrated reduced absorption capacities. The absorption capacity decreased gradually with an increase in CS content, as observed in CA4, which had the lowest absorption values (28.89 ± 1.53 g/g for MFO, 26.05 ± 0.31 g/g for PO, and 19.26 ± 1.12 g/g for HSD). This result aligns with the findings of previous research, where increased filler content was associated with a decrease in pore volume and size, thereby limiting the material’s capacity for oil absorption [3,8,26,36]. However, the inclusion of CS in CAn improved the aerogel’s structural stability, resulting in better reusability, which is an advantage over some other biomass-based carbon aerogels that suffer from structural collapse after a few absorption cycles. The statistical analysis further confirmed that the addition of chitosan (CS) significantly affected the absorption capacity of CAn for various oils. Table 6. Absorption capacities of CAn for various oils (Notes: MFO = Marine Fuel Oil; PO = Palm Oil; HSD = High-Speed Diesel; Values in columns with different letters in superscripts indicate significant differences, p < 0.05) Sample code Absorption capacity (g/g) MFO PO HSD Control 76.27±1.05 a 72.31±1.97 a 55.70±1.56 a CA1 49.55±0.38 b 69.05±1.10 b 54.50±1.34 a CA2 46.88±1.34 c 31.55±1.18 c 33.72±1.75 b CA3 33.00±1.64 d 29.61±1.32 c 27.63±1.65 c CA4 28.89±1.53 e 26.05±0.31 d 19.26±1.12 d Table 7. Reusability of CAn for various oils (Notes: PO = Palm Oil; HSD = High-Speed Diesel; each sample code has triple replicates) Sample code PO HSD Control 1 1 CA1 4-5 24-26 CA2 11-12 10-12 CA3 4-5 11-10 CA4 5-6 8-9 The reusability of the CAn was evaluated through repeated absorption and desorption cycles, and the results are summarized in Table 7 . Reusability is a crucial property for oil absorption materials in oil-water separation applications. Notably, MFO was not used for repeated cycles due to its thicker texture and tendency to solidify, which complicates the desorption process. From the result exhibited that control samples had the lowest reusability despite their high initial absorption capacity. This outcome suggests that while the control samples have a high capacity, their structural integrity is compromised during repeated use. Unlike some carbon aerogels documented in earlier studies, which often exhibit high initial absorption capacity but low reusability due to brittleness [25]. The CAn with CS incorporation exhibited improved reusability. However, excessive amounts of CS resulted in a decrease in absorption capacity and flexibility, as shown in the case of CA4. This observation differs from the outcomes reported in some previous research, where fillers were added without significantly impacting the absorption capacity. The densification of the pore structure in CAn due to high CS content appears to reduce oil storage space, thereby lowering its absorption capacity. Despite this reduction, the stability imparted by CS addition resulted in enhanced reusability, a feature that many traditional carbon aerogels lack. The absorption process of CAn is illustrated in Figure 7(a) and Figure 7(b) , where the aerogels rapidly absorb MFO and HSD, respectively, leaving clean water behind. The absorption process visualized in Figure 7 aligns with the known properties of hydrophobic and oleophilic carbon aerogels. The rapid absorption of MFO and HSD confirms the aerogels’ selectivity for oil, leaving clean water in their wake. This characteristic make CAn a competitive alternative for oil spill remediation, combining both high initial absorption capacity and the ability to withstand multiple usage cycles. This efficient absorption showcases the potential of CAn in environmental applications. The CAn samples with optimized CS content (e.g., CA2-3 and CA2-4) present a balanced performance with moderate absorption capacities and enhanced reusability. This indicates that CS not only modifies the pore structure, making it denser, but also reinforces the aerogel’s mechanical stability. These findings provide new insights into how the controlled addition of CS can improve the durability of carbon aerogels, distinguishing CAn from other biomass-derived carbon aerogels. By tuning the CS content, it is possible to fabricate aerogels with tailored properties for specific applications, offering a path forward in the development of multifunctional absorbent materials. To extract the absorbed oil, a 50% compression of the aerogel height was applied using an injection pump, as shown in Figure 8(a) . The CA structure remained stable during initial compressions, but eventually ruptured with excessive reuse, as depicted in Figure 8(b) . Furthermore, the comparison with other studies in Table 8 shows that CAn exhibits a balanced performance, combining substantial absorption capacities with excellent reusability, positioning it as a versatile and sustainable material for environmental applications. The research on CAn carbon aerogels reveals a promising material that balances absorption capacity with structural reusability and chitosan content. These properties make CAn a viable candidate for oil spill remediation and other environmental applications where selective liquid absorption is critical. By showcasing the benefits of using renewable biomass and optimizing material composition, this study contributes to the ongoing efforts to develop efficient, cost-effective, and eco-friendly solutions for environmental cleanup. Table 8. Comparison of carbon aerogel-based materials from this study with previous research regarding oil absorption capacity and reusability Material Capacities Absorption (g/g) Substance Oil Reusability References CFAs from sisal leaves 90 – 188 Organic solution, diesel oil, and soy oil >10 [35] CA derived from Platanus orientalis 30–150 Oil/water mixtures, and water-in-kerosene emulsion 6 [37] Graphene/polyvinyl alcohol/CNF carbon aerogel 155 – 288 Pump oil, corn oil, and ethanol >10 [38] Carbon aerogel from sugarcane bagasse 31.9 – 55.02 Silicone oil, edible oil, castor oil, and soybean oil - [29] Aerogel from celulosa/tannic acid/castor oil 53.2 – 113.8 Organic solution, olive oil 10 [39] Carbon aerogel chitosan-citric acid 40 – 125 Polymorphic oils - [40] This work 20 – 84 Marine fuel oil, high speed diesel, palm oil 2 - 26 - 3.6. Antimicrobial activity The antimicrobial activity of carbon aerogels (CA) functionalized with silver nanowires (AgNWs) was evaluated to assess their effectiveness against different bacterial strains. AgNWs were synthesized using a modified solvothermal method, where ethylene glycol acted as both the solvent and a reducing agent precursor, polyvinylpyrrolidone (PVP) served as a stabilizer, and FeCl 3 functioned as a reducing agent. The resulting AgNWs exhibited a diameter of approximately 100 nm and a length ranging from 10 to 50 μm, as shown in Figure 9(a) . The distribution of AgNWs on the three-dimensional CA structure was achieved via a dip-coating method. Figure 9(b) illustrates the uniform dispersion of AgNWs across each layer of the CA, indicating that the dip-coating technique is effective for incorporating AgNWs into the aerogel matrix. This uniform distribution is crucial for maximizing the antimicrobial activity of the functionalized aerogel. Additionally, the distribution of AgNWs onto the CA structure, as shown in Figure 9(b) , plays a crucial role in the antimicrobial performance. The dip-coating method employed in this study ensures a uniform spread of AgNWs across the aerogel layers, enhancing contact with bacterial cells and facilitating antimicrobial action. This method of AgNWs incorporation into carbon aerogels contrasts with other studies, where silver nanoparticles (AgNPs) were embedded within the aerogel matrix. Although AgNPs also exhibit antimicrobial properties, their uniform distribution is often challenging to achieve, potentially limiting their effectiveness compared to the dip-coated AgNWs [41]. To evaluate the antibacterial properties of the CA-AgNWs composites, the aerogels were loaded with different concentrations of AgNWs (0.5%, 1%, 2%, 5%, and 7%) and exposed to bacterial cells using a diffusion method. The average diameters of the clear inhibitory zones for Escherichia coli , Staphylococcus aureus , and Salmonella typhi are presented in Table 9 . The results show that AgNWs were more effective against Gram-negative (G-) bacteria ( E. coli and S. typhi ) than against Gram-positive (G+) bacteria ( S. aureus ). This enhanced sensitivity to G- bacteria is likely due to the presence of lipopolysaccharides in the outer membrane of G- bacteria, which have a higher affinity for AgNWs compared to the peptidoglycan layer in G+ bacterial cell walls. Additionally, the lipopolysaccharides may trap and block the Ag+ cations, enhancing the antimicrobial effect [41,42]. In contrast, Gram-positive bacteria, such as S. aureus , have a thicker peptidoglycan layer that provides more resistance to the penetration of AgNWs. However, the present study reveals that even at lower concentrations (0.5% AgNWs), the CA-AgNWs composites exhibit significant inhibitory effects on S. aureus , indicating the potential of these aerogels as broad-spectrum antimicrobial agents. This performance surpasses that of some previously reported silver-based antimicrobial materials, which often require higher concentrations to achieve similar levels of inhibition against Gram-positive bacteria [43]. Furthermore, AgNWs can interact with the membrane surface and penetrate bacterial cells. When AgNWs enter the cells via endocytosis, they are exposed to the acidic environment of cell lysosomes, which induces the production of reactive oxygen species, leading to cell membrane rupture and triggering apoptosis [43,44]. To further investigate the antibacterial mechanism, the inhibited zones were collected and examined using scanning electron microscopy (SEM). The SEM images in Figure 9(c) and Figure 9(d) display the damaged cell membranes of E. coli and S. typhi , respectively, confirming the antimicrobial action of AgNWs. Table 9. The average diameter of the clear inhibitory zone for E. coli , S. aureus , and S. typhi at varying AgNWs concentrations Sample code Diameter of clear inhibitory (mm) E. coli S. aureus S. typhi Control (-) 6.00 5.50 5.67 CA-0.5 10.50 7.33 7.67 CA-1 12.50 8.17 8.00 CA-2 13.33 9.33 9.33 CA-5 13.67 10.00 11.33 CA-7 14.55 10.55 12.67 In practical terms, the CA-AgNWs composites offer promising applications in areas that require both adsorption and antimicrobial functions. The composite’s ability to inhibit microbial growth at relatively low AgNWs concentrations makes it a cost-effective option for water purification, where the removal of both pollutants and pathogens is essential. The effectiveness of the composites against Gram-negative bacteria, which are often more resistant to traditional disinfectants, further emphasizes their utility in water treatment processes. 4. Conclusion This study successfully developed carbon aerogels (CAn-x) derived from oil palm fronds (OPF) reinforced with chitosan (CS) and incorporated silver nanowires (AgNWs) for enhanced oil absorption and antimicrobial applications. The fabrication process, including the selection of optimal CNF to CS mass ratios that significantly influenced the density, porosity, surface area, and wettability of the aerogels, resulting in materials with excellent absorption capacity and selective oil absorption properties. The highest absorption capacities were observed in control samples with larger pore volumes, while the addition of chitosan enhanced the aerogel’s structural integrity and reusability. The incorporation of AgNWs into the aerogels imparted strong antimicrobial activity, particularly against Gram-negative bacteria such as E. coli and S. typhi . The uniform distribution of AgNWs achieved through the dip-coating method ensured effective contact with bacterial cells, as evidenced by clear inhibitory zones. These findings highlight the versatility of CA-AgNWs as multifunctional materials suitable for environmental applications, including oil spill remediation and water purification, as well as potential uses in medical fields requiring antibacterial properties. This research demonstrates the potential of renewable biomass, such as OPF, in creating high-performance, sustainable aerogels with tailored properties for various practical applications. Future work may focus on optimizing the composition and processing conditions further to maximize absorption efficiency, mechanical strength, and long-term antimicrobial performance. Declarations Declaration of Generative AI and AI-assisted technologies in the writing process During the preparation of this work the author(s) used ChatGPT 4o in order to correct grammar and spelling errors, enhance the language, and improve overall readability. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication. CRediT author statement Bernadeta Ayu Widyaningrum: Conceptualization, Methodology, Writing - Original Draft, Writing - Review & Editing, Supervision; Sudarmanto: Investigation; Lu’lu’ Qurrotul ‘Ain Hariri: Investigation; Hendrawati: Validation; Riska Surya Ningrum: Investigation, Resources; Dwi Ajias Pramasari: Formal analysis; Andrew Nosakhare Amenaghawon: Validation; Noureddine El Messaoudi: Validation; Tonni Agustiono Kurniawan: Validation; Handoko Darmokoesoemo: Validation; Heri Septya Kusuma: Validation, Writing - Review & Editing, Supervision. References R.K. 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Widyaningrum","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA6UlEQVRIiWNgGAWjYDCCAyCiAojZG4CEgQUxWpgZGxjOABk8IM0GEkRqYWwDMiQSQFwitPAd7z/+4Gcbg7zBzedXN/wokGDgb+9OwKtF8sxhxsaecwyGG27nlN3sATpM4szZDXi1GNxIZmzgKWNgBGpJu8ED1GIgkUtAy/3HjI1/2BjsN9w8k3bzD1FabjAzNvO0MSRuuMF+7DZRtkieSTacLXNGInnmmRy22zIGEjwE/cJ3/OCDj28qbGz7jh9/dvPNHxs5/vZe/FqgQIJB4QCPAYjFQ4xyCJBvYH9AvOpRMApGwSgYUQAActhOpHbk9GoAAAAASUVORK5CYII=","orcid":"","institution":"National Research and Innovation Agency (BRIN)","correspondingAuthor":true,"prefix":"","firstName":"Bernadeta","middleName":"Ayu","lastName":"Widyaningrum","suffix":""},{"id":501341044,"identity":"f57248c1-b4fd-480a-94d1-59350e97fe26","order_by":1,"name":"- Sudarmanto","email":"","orcid":"","institution":"National Research and Innovation Agency (BRIN)","correspondingAuthor":false,"prefix":"","firstName":"-","middleName":"","lastName":"Sudarmanto","suffix":""},{"id":501341045,"identity":"3e1a6ad8-c10a-45fe-a29e-d79a79e934dd","order_by":2,"name":"Lu’lu ’ Qurrotul ‘Ain Hariri","email":"","orcid":"","institution":"Universitas Islam Negeri Syarif Hidayatullah","correspondingAuthor":false,"prefix":"","firstName":"Lu’lu","middleName":"’ Qurrotul ‘Ain","lastName":"Hariri","suffix":""},{"id":501341047,"identity":"ab4676d3-75dd-4fad-99b4-df3eb8d59df0","order_by":3,"name":"- Hendrawati","email":"","orcid":"","institution":"Universitas Islam Negeri Syarif Hidayatullah","correspondingAuthor":false,"prefix":"","firstName":"-","middleName":"","lastName":"Hendrawati","suffix":""},{"id":501341049,"identity":"810894a7-49d4-4487-bf91-a822292dc635","order_by":4,"name":"Riska Surya Ningrum","email":"","orcid":"","institution":"National Research and Innovation Agency (BRIN)","correspondingAuthor":false,"prefix":"","firstName":"Riska","middleName":"Surya","lastName":"Ningrum","suffix":""},{"id":501341051,"identity":"8e18df86-4acb-4e50-a094-fc739f921993","order_by":5,"name":"Dwi Ajias Pramasari","email":"","orcid":"","institution":"National Research and Innovation Agency (BRIN)","correspondingAuthor":false,"prefix":"","firstName":"Dwi","middleName":"Ajias","lastName":"Pramasari","suffix":""},{"id":501341053,"identity":"7a44e36e-9653-44a1-9114-61726b2d640b","order_by":6,"name":"Andrew Nosakhare Amenaghawon","email":"","orcid":"","institution":"University of Benin","correspondingAuthor":false,"prefix":"","firstName":"Andrew","middleName":"Nosakhare","lastName":"Amenaghawon","suffix":""},{"id":501341055,"identity":"71b3e5cd-ec1d-42c8-b4a3-957756e997ee","order_by":7,"name":"Noureddine El Messaoudi","email":"","orcid":"","institution":"Ibn Zohr University","correspondingAuthor":false,"prefix":"","firstName":"Noureddine","middleName":"El","lastName":"Messaoudi","suffix":""},{"id":501341057,"identity":"754238f6-5156-4fd7-baa5-f86ea5891025","order_by":8,"name":"Tonni Agustiono Kurniawan","email":"","orcid":"","institution":"Xiamen University","correspondingAuthor":false,"prefix":"","firstName":"Tonni","middleName":"Agustiono","lastName":"Kurniawan","suffix":""},{"id":501341058,"identity":"57c4b2c4-8347-4edd-a4a2-cd5732f40b82","order_by":9,"name":"Handoko Darmokoesoemo","email":"","orcid":"","institution":"Airlangga University","correspondingAuthor":false,"prefix":"","firstName":"Handoko","middleName":"","lastName":"Darmokoesoemo","suffix":""},{"id":501341059,"identity":"75344319-d97f-484e-a2aa-9f961fa243c1","order_by":10,"name":"Heri Septya Kusuma","email":"","orcid":"","institution":"Universitas Pembangunan Nasional “Veteran” Yogyakarta","correspondingAuthor":false,"prefix":"","firstName":"Heri","middleName":"Septya","lastName":"Kusuma","suffix":""}],"badges":[],"createdAt":"2025-08-01 08:53:22","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7269305/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7269305/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10934-025-01865-z","type":"published","date":"2025-10-19T15:58:13+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":89392615,"identity":"699f5c88-7cb0-4e72-8ef3-da7b72e6a213","added_by":"auto","created_at":"2025-08-19 13:18:36","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1226494,"visible":true,"origin":"","legend":"\u003cp\u003e(a) Schematic representation of the synthesis of CAn-x from oil palm fronds via freeze-drying and carbonization; (b) TEM image of CNF at 500 nm scale; (c) TEM image of CNF at 1 μm scale.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/08a99c55048bae9b06f5a4e3.png"},{"id":89392614,"identity":"d2a24f20-dc09-4a8e-a342-9169a5db2e0b","added_by":"auto","created_at":"2025-08-19 13:18:36","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":385982,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM images of OPF-derived aerogels: (a) axial direction shows a rough, flaky surface; (b) radial direction exhibits a more compact layered morphology.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/a1931a648378051d26725341.png"},{"id":89392112,"identity":"cbc84838-b35f-4a1d-af5b-e0f1c10486c0","added_by":"auto","created_at":"2025-08-19 13:10:36","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":1930256,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of carbon aerogels after carbonization at 300 °C: (a) CA1; (b) CA2; (c) CA3; (d) CA4. Images reveal differences in porosity and layer structure with varying CNF:CS ratios.\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/eca53ab649fd685c6377e391.png"},{"id":89392121,"identity":"422132ee-97ce-4099-8851-cb8a596ea80e","added_by":"auto","created_at":"2025-08-19 13:10:36","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":206263,"visible":true,"origin":"","legend":"\u003cp\u003eDemonstration of the ultralight property of carbon aerogel (CA) balancing on a grass blade, indicating low density.\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/cd38840ed0f524934c50047b.png"},{"id":89393885,"identity":"80d0b4a0-e9a1-469d-94d8-7a87979f51ad","added_by":"auto","created_at":"2025-08-19 13:26:36","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":338287,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of samples: (a) raw materials and aerogel composites including CNF, CS, and aerogel 1–4; (b) carbon aerogels (CA1–CA4) and comparison with CNF and CS after carbonization at 300 °C.\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/641b06e03eb7645220722989.png"},{"id":89392619,"identity":"73ae2f5c-e096-45f7-893a-bb5ee33e7e6e","added_by":"auto","created_at":"2025-08-19 13:18:36","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":919906,"visible":true,"origin":"","legend":"\u003cp\u003eSurface wettability and selectivity of CAn-x: (a) water droplets remain spherical on the superhydrophobic surface; (b) oil penetrates the aerogel, while water remains on the surface.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/3388907034a401ad38490f4f.png"},{"id":89392617,"identity":"33acdd7f-a48d-411b-96e0-0a45be330483","added_by":"auto","created_at":"2025-08-19 13:18:36","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":893497,"visible":true,"origin":"","legend":"\u003cp\u003eOil absorption performance of carbon aerogels: (a) sequential images of marine fuel oil (MFO) absorption before and after application; (b) images showing high-speed diesel (HSD) absorption behavior.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/500eb22085978699159dc5dc.png"},{"id":89392130,"identity":"0e1d5543-7413-4eea-a60c-3a7f0942ceb6","added_by":"auto","created_at":"2025-08-19 13:10:36","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":811806,"visible":true,"origin":"","legend":"\u003cp\u003eMechanical stability of CAn-x during reusability test: (a) compression using a syringe to simulate absorption-desorption cycles; (b) eventual rupture of the aerogel structure after repeated use.\u003c/p\u003e","description":"","filename":"8.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/ba5bcfb685245a368412fbe6.png"},{"id":89392616,"identity":"6e190f0e-4ece-443a-aa25-f5f6ae4a6d57","added_by":"auto","created_at":"2025-08-19 13:18:36","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":958065,"visible":true,"origin":"","legend":"\u003cp\u003eSEM characterization of AgNWs and antibacterial performance: (a) SEM of silver nanowire network; (b) distribution of AgNWs across CA surface; (c) magnified SEM showing inhibition of \u003cem\u003eE. coli\u003c/em\u003e; (d) inhibition of \u003cem\u003eS. typhi\u003c/em\u003e growth.\u003c/p\u003e","description":"","filename":"9.png","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/c0a0f0d6c441fd7e5270d2f8.png"},{"id":93956058,"identity":"2b067ef1-76a3-4a09-a37a-8e8ee4ca9885","added_by":"auto","created_at":"2025-10-20 16:09:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":10058256,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7269305/v1/080a6fa2-a652-488b-aa5a-964c37ecbc2e.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Chitosan-Reinforced Carbon Aerogels from Oil Palm Fronds for Enhanced Oil Absorption and Silver Nanowires Loaded as Antimicrobial Activity","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eEnvironmental and ecological issues arising from crude oil spills, petroleum products, and toxic organic solvents present significant challenges that demand immediate attention. Annually, numerous incidents of oil spills occur in marine environments, leading to severe damage to wildlife habitats, economic disruption, and health hazards to humans. Various methods, including physical diffusion, biological and chemical treatments, in situ burning, and biodegradation, have been employed to mitigate these environmental impacts [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. However, absorption stands out as an effective, cost-efficient, and environmentally friendly method for oil spill remediation. The development of ideal absorbent materials requires a combination of high absorption capacity, selectivity, reusability, and eco-friendliness. Carbon aerogels (CA) have garnered attention due to their porous, three-dimensional (3D) interconnected networks, which exhibit unique wetting properties suitable for effective oil/water separation [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. The 3D structure of CA, coupled with properties such as low density, high porosity, large specific surface area, and hydrophobicity, enhances their absorption capacity and selectivity for oils and organic solvents [\u003cspan additionalcitationids=\"CR3 CR4 CR5\" citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e] The open porous network of CA allows for efficient molecular access and penetration into their inner structures [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eRecently, the use of biomass as a precursor for carbon-based materials has gained increasing interest due to its cost-effectiveness, abundance, sustainability, and ease of procurement [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan additionalcitationids=\"CR8\" citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Several studies have reported the fabrication of cellulose-based carbon aerogels from various biomass sources [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e], such as winter melon melon [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], cotton [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], poplar catkin [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], straw [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e], bamboo [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] and softwood kraft [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. Indonesia, with its vast palm oil plantations, produces a considerable amount of oil palm fronds (OPF), which are often underutilized and considered waste. Given that OPF contains significant amounts of α-cellulose, hemicellulose, and lignin [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], it presents an excellent source for creating carbon aerogels for oil/water absorption applications. However, traditional carbon aerogels have limitation especially in their reusability because their structure is very brittle. To address the limitations of conventional oil absorbent materials, researchers have explored the fabrication of carbon aerogel composites using various organic and inorganic fillers. Chitosan, a natural polysaccharide, has gained significant attention as a reinforcing filler in carbon aerogels due to its mechanical strengthening capabilities and biocompatibility. Studies have shown that integrating chitosan into the aerogel matrix improves the mechanical stability of the material, mitigating brittleness and enhancing reusability [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. The layered sheets formed by chitosan provide a connective framework within the aerogel, thereby increasing its toughness and durability [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Silver nanowires (AgNWs) is one of antimicrobial agents with unique structure. Silver ions possess antibacterial properties that can inhibit protein activity and DNA replication in bacterial cells [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. Furthermore, several studies have acknowledged their properties in mitigating biofouling cells [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. It gives great prospects to combine AgNWs onto CA structure to create advanced absorbent materials that meet the demands of environmental cleanup operations.\u003c/p\u003e\u003cp\u003eHerein, a 3D structure of CA with AgNWs loading (CA-AgNWs) has been successfully fabricated from OPF using a freeze-drying method and low carbonization temperature, making it more energy-efficient and environmentally friendly. In addition, the CA-AgNWs exhibited good adsorption capacity for various oils reached up to 72 times its weight and can maintain its structure after 36 cycles by squeezing. The AgNWs loading into CA shows well-dispersed and antimicrobial activity. The findings of this research are expected to contribute to the development of more efficient, sustainable, and multifunctional absorbent materials for environmental cleanup operations, particularly in the context of oil spill remediation.\u003c/p\u003e"},{"header":"2. Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003e2.1. Materials\u003c/h2\u003e\u003cp\u003eThe primary materials used in this study include oil palm fronds (OPF) waste, technical chitosan (CS) derived from shrimp with a deacetylation degree of less than 90%, acetic acid (CH\u003csub\u003e3\u003c/sub\u003eCOOH, Merck, Singapore), silver nitrate (AgNO\u003csub\u003e3\u003c/sub\u003e, Merck, Germany), ethylene glycol (EG, Merck, Singapore), polyvinylpyrrolidone (PVP, Sigma, Singapore), iron (III) chloride hexahydrate (FeCl\u003csub\u003e3\u003c/sub\u003e\u0026middot;6H\u003csub\u003e2\u003c/sub\u003eO, Merck, Singapore), and acetone (Merck, Singapore). Nutrient agar and nutrient broth were purchased from Himedia, in Indonesia. Deionized water, used throughout the study was sourced from a local supplier to ensure consistent quality.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\u003ch2\u003e2.2. Extraction of biomass cellulose\u003c/h2\u003e\u003cp\u003eOil palm fronds (OPF) were sourced from the Research Centre for Biomass and Bioproduct - BRIN, Cibinong. The fronds were initially chopped and sieved to a 60-mesh size to standardize the particle dimensions. To remove impurities, the sieved biomass was washed thoroughly in water and ethanol three times. This washing process ensured the elimination of surface contaminants and unwanted organic substances.\u003c/p\u003e\u003cp\u003eThe delignification of the OPF was conducted using a sodium hydroxide (NaOH) solution at a concentration of 9% w/v. The delignification process was carried out in a heated reactor at 170\u003csup\u003eo\u003c/sup\u003eC for 1 hour. After this treatment, the pulp was thoroughly washed with deionized water until the pH reached a neutral level. The washed pulp was then dried in an oven at 60\u003csup\u003eo\u003c/sup\u003eC for 24 hours. The dried pulp is then stored for further processing.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\u003ch2\u003e2.3. Preparation of cellulose nanofibril (CNF)\u003c/h2\u003e\u003cp\u003eThe dried cellulose pulp obtained from the oil palm fronds (OPF) was first soaked in deionized water for 24 hours to facilitate hydration and soften the fibers. The hydrated pulp was then processed using a Masuko Sangyo Supermass colloider grinder (MKCA6-3; Masuko Sangyo Co., Ltd.) to produce cellulose nanofibrils (CNF).\u003c/p\u003e\u003cp\u003eThe defibrillation process was carried out at a concentration of 1.0 wt% cellulose. The grinding was conducted over five cycles at a rotation speed of 1500 rpm, with the gap between the stone plates gradually adjusted to optimize fibrillation. The resulting CNF suspension exhibited a gel-like consistency, indicating the successful breakdown of the cellulose fibers into nanoscale fibrils. This CNF served as a key structural component in the fabrication of the carbon aerogel (CA).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003e2.4. Synthesis of the AgNWs\u003c/h2\u003e\u003cp\u003eThe silver nanowires (AgNWs) were synthesized using a modified solvothermal method based on the procedure outlined in our previous work [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. The synthesis was conducted in a Teflon-lined autoclave to ensure a controlled reaction environment. Initially, an ethylene glycol (EG) solution containing 0.1 M silver nitrate (AgNO\u003csub\u003e3\u003c/sub\u003e) was prepared and poured into the reactor. The mixture was heated under stirring until the temperature reached 170\u003csup\u003eo\u003c/sup\u003eC, allowing the AgNO\u003csub\u003e3\u003c/sub\u003e to dissolve completely. Following this, an EG solution containing 0.1 mM iron (III) chloride (FeCl\u003csub\u003e3\u003c/sub\u003e) and 0.417 g of polyvinylpyrrolidone (PVP) was introduced into the autoclave using a syringe to ensure a gradual addition. The mixture was then heated for 2.5 hours under isolated conditions to promote the growth of AgNWs. The resultant solution was subjected to sonication to ensure the complete dispersion of AgNWs. It was then rinsed three times with acetone to remove any unreacted precursors and excess PVP. The final solid product, AgNWs, was collected and stored for further use.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\u003ch2\u003e2.5. Fabrication of carbon aerogel (CAn)\u003c/h2\u003e\u003cp\u003eThe fabrication of carbon aerogels (CAn) involved the preparation of cellulose-based aerogels with chitosan (CS) as a reinforcing filler. The process began with preparing a mixture containing 1% cellulose nanofibril (CNF) and 2% chitosan dissolved in 1% acetic acid solution. Different mass ratios of CNF to CS (n\u0026thinsp;=\u0026thinsp;2:1, 1:1, 1:2, and 1:3) were prepared to investigate the effect of varying filler content on the properties of the aerogel. Each mixture was stirred thoroughly to ensure homogeneity, followed by pouring into mold containers. The mixtures were then cooled at -20\u003csup\u003eo\u003c/sup\u003eC for 24 hours and continue to dry using freeze-dryer, which resulted in lightweight, porous aerogels.\u003c/p\u003e\u003cp\u003eSubsequently, the aerogels were subjected to a carbonization process to convert them into carbon aerogels. The aerogels were placed in a tube furnace under a nitrogen atmosphere and heated to the target temperatures of 300\u003csup\u003eo\u003c/sup\u003eC. The temperature was increased at a rate of 10\u0026deg;C per minute and maintained at the target temperature for 2 hours. The nitrogen atmosphere was maintained throughout the carbonization process to prevent oxidation. The specific sample codes for each carbon aerogel are listed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSample codes of carbon aerogels (CAn)\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSample Code\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMass Ratio CNF to CS\u003c/p\u003e\u003cp\u003e(n)\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCA1\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e2:1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCA2\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1:1\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCA3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1:2\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003eCA4\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e1:3\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003e2.6. AgNWs loading into CAn-X\u003c/h2\u003e\u003cp\u003eThe incorporation of AgNWs into the CA was performed using a dip-coating technique to ensure an even distribution of AgNWs on the aerogel surface. Initially, AgNWs were dispersed in acetone at various concentrations (X\u0026thinsp;=\u0026thinsp;0.5%, 1%, 2%, 5%, and 7%) and then subjected to sonication for 30 minutes. This sonication step helped to break up any agglomerates and achieve a uniform suspension of AgNWs, facilitating their effective loading onto the aerogels. After dipping, the aerogels were quickly dried in an oven at 105\u003csup\u003eo\u003c/sup\u003eC for 5 minutes to evaporate the acetone and fix the AgNWs onto the surface.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\u003ch2\u003e2.7. Characterization\u003c/h2\u003e\u003cp\u003eThe characterization of the CNF, CAn, and CAn-X was conducted using various analytical techniques to understand their structural, morphological, and functional properties. The morphology of the CNF was observed using a Transmission Electron Microscope (TEM, Tecnai G2 20S-Twin). The TEM analysis provided information on the size and fibrillation degree of the CNF, confirming the nanoscale dimensions. The macrostructure of the CAn-x aerogels and the distribution of AgNWs were examined using a Field Emission Scanning Electron Microscope (FESEM, Thermo Scientific Quattro S). The functional groups were analyzed using Fourier Transform Infrared Spectroscopy (FTIR, ATR-Perkin Elmer). FTIR spectra were recorded in the range of 4000 to 500 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to identify the chemical bonds and functional groups. The Brunauer\u0026ndash;Emmett\u0026ndash;Teller (BET, Quantachrome Nova 4200e) with BJH method was used to evaluate the surface area and pore structure. The hydrophobic properties of the were assessed using a digital microscope (Dino-Lite). Water contact angles (WCA) were measured to evaluate the surface wettability and hydrophobicity of the aerogels, which directly influence their oil absorption selectivity.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e\u003ch2\u003e2.8. Density and porosity\u003c/h2\u003e\u003cp\u003eThe density (\u003cem\u003eρ\u003c/em\u003e) of the CAn was determined by measuring their mass and volume, in this measurement we use triple replication. The mass was obtained using a precision analytical balance, and the volume was calculated based on the dimensions (height and diameter) of the cylindrical aerogel samples. The density was then calculated using Eq.\u0026nbsp;(\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e):\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:\\rho\\:=\\frac{m}{v}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003em\u003c/em\u003e represents the mass of the carbon aerogel and \u003cem\u003ev\u003c/em\u003e is the volume.\u003c/p\u003e\u003cp\u003eThe porosity (\u003cem\u003eP\u003c/em\u003e) of the carbon aerogels was assessed using Eq.\u0026nbsp;(\u003cspan refid=\"Equ2\" class=\"InternalRef\"\u003e2\u003c/span\u003e):\u003cdiv id=\"Equ2\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ2\" name=\"EquationSource\"\u003e\n$$\\:P=\\left(1-\\frac{\\rho\\:}{{\\rho\\:}_{s}}\\right)\\times\\:100$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e2\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003eρ\u003c/em\u003e is the density of the carbon aerogel obtained from Eq.\u0026nbsp;(\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e), and \u003cem\u003eρ\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e is the density of the solid material. The solid material density \u003cem\u003eρ\u003c/em\u003e\u003csub\u003e\u003cem\u003es\u003c/em\u003e\u003c/sub\u003e was assumed based on the theoretical density of carbon, given the carbonization of the cellulose and chitosan components.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003e2.9. Absorption capacity and reusability\u003c/h2\u003e\u003cp\u003eThe absorption capacity (\u003cem\u003eC\u003c/em\u003e) of the carbon aerogels (CAn) was evaluated using three different types of oils: marine fuel oil (MFO), palm oil (PO), and high-speed diesel oil (HSD). To conduct the absorption test, each sample was weighed before and after immersion in the oil with triple replicates, allowing the calculation of absorption capacity using Eq.\u0026nbsp;(\u003cspan refid=\"Equ3\" class=\"InternalRef\"\u003e3\u003c/span\u003e):\u003cdiv id=\"Equ3\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ3\" name=\"EquationSource\"\u003e\n$$\\:C=\\frac{\\left(m-{m}_{0}\\right)}{{m}_{0}}$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e3\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e\u003cp\u003ewhere \u003cem\u003eC\u003c/em\u003e is the absorption capacity (g/g), \u003cem\u003em\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e is the initial weight of the dry sample, and \u003cem\u003em\u003c/em\u003e is the weight of the samples after oil absorption. The samples were fully immersed in oil for a specified time to ensure saturation. After immersion, the samples were removed, excess surface oil was carefully blotted off, and the final weight was recorded. Each absorption test was repeated three times, and the average value was used to ensure the accuracy of the results.\u003c/p\u003e\u003cp\u003eThe reusability of the CAn was determined by conducting cyclic squeezing tests. After absorption, the aerogels were compressed using a piston pump to 40% of their original height to expel the absorbed oil. After squeezing, the samples were immediately immersed back into the oil for the next absorption cycles. This process was repeated until the CA showed signs of structural damage or collapse, which marked the end of its reusability. The number of successful absorption-desorption cycles before damage was recorded as the aerogel\u0026rsquo;s reusability metric. The absorption capacity and reusability tests provided valuable data on the aerogels\u0026rsquo; oil absorption performance and durability. For each experiment absorption capacity and reusability, we use triple replicates.\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\u003ch2\u003e2.10. Antibacterial test\u003c/h2\u003e\u003cp\u003eThe antibacterial activity of the CAn-X was assessed using the agar diffusion method. The plates were incubated at 37\u0026deg;C for 24 hours to allow bacterial growth and diffusion of the antimicrobial agent from the samples into the surrounding agar medium. Following incubation, the antimicrobial activity was determined by measuring the diameter of the clear inhibitory zones formed around each CAn-X. These zones indicated the area where bacterial growth was inhibited due to the antimicrobial effect of the AgNWs on the samples. The average diameter of the inhibition zones for each bacterial strain was recorded to quantify the antibacterial performance of the samples. This test was performed to evaluate the antimicrobial effectiveness of the CAn-X against both Gram-positive and Gram-negative bacteria. The bacterial strains used in this study were \u003cem\u003eStaphylococcus aureus\u003c/em\u003e (Gram-positive), \u003cem\u003eSalmonella typhi\u003c/em\u003e, and \u003cem\u003eEscherichia coli\u003c/em\u003e (both Gram-negative).\u003c/p\u003e\u003c/div\u003e\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\u003ch2\u003e2.11. Statistical Analysis of Carbon Aerogel (CAn-X)\u003c/h2\u003e\u003cp\u003eThe data obtained from the experiments, including the measurements of density, porosity, absorption capacity, reusability of the CAn, and antibacterial activity of CAn-X, were statistically analyzed using STAR (Statistical Tool for Agricultural Research) software version 2.0.1, developed by the International Rice Research Institute. The statistical analysis aimed to determine the influence of different treatments on the properties of the CA.\u003c/p\u003e\u003cp\u003eA single-factor completely randomized design (CRD) was used in this study, ensuring that all treatment conditions were replicated a minimum of three times for accuracy. The effects of varying mass ratios of cellulose nanofibrils (CNF) to CS and AgNWs loading were assessed using one-way analysis of variance (ANOVA). This analysis identified the significance of individual and interactive effects of the variables on the aerogel properties.\u003c/p\u003e\u003cp\u003eWhen the ANOVA results indicated significant differences (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05) among the treatments, Duncan\u0026rsquo;s Multiple Range Test (DMRT) was employed to compare the means and ascertain the specific treatments that differed significantly. This statistical approach ensured a comprehensive understanding of how each factor contributed to the physical, chemical, and functional characteristics of the CAn-X.\u003c/p\u003e\u003c/div\u003e"},{"header":"3. Results and Discussion","content":"\u003cp\u003e3.1. Preparation and characterization of CAn\u003c/p\u003e\n\u003cp\u003eThe preparation and characterization of the CAn composites were fabricated by a series of steps of defibrillation, freeze-drying, and carbonization as illustrated in \u003cstrong\u003eFigure 1(a)\u003c/strong\u003e. At the first step cellulose nanofibers (CNF) were extracted from oil palm fronds (OPF) via a mechanical process. The transmission electron microscope (TEM) images of CNF shown in \u003cstrong\u003eFigure 1(b)\u003c/strong\u003e, revealed a single round and long fiber, and the high magnification TEM image (\u003cstrong\u003eFigure 1(c)\u003c/strong\u003e) shows the single cellulose has a diameter ranging between 10 and 47 nm, indicating successful fibrillation of the cellulose nanofibers. Cellulose as natural resources were chosen due to high polymerization, chemical durability, and mechanical stability. These properties are attributed to the strong intermolecular hydrogen bonds, which facilitate the formation of interconnected three-dimensional (3D) network structures [20].\u003c/p\u003e\n\u003cp\u003eThe next step was fabrication of OPF aerogels. This step was subsequently prepared by mixing CNF and chitosan (CS) in various mass ratios, followed by a freeze-drying process to form a porous structure. Field Emission Scanning Electron Microscopy (FESEM) images in \u003cstrong\u003eFigure 2\u003c/strong\u003e demonstrate the morphology of the aerogel. FESEM showed that aerogel had an irregular, rough, and slightly porous surface in the axial direction, while the radial direction appears smoother and more layered. These morphological features suggest that the aerogel structure is suitable to form a carbon network upon carbonization.\u003c/p\u003e\n\u003cp\u003eThe OPF aerogels were then subjected to thermal treatment through a carbonization process at temperatures of 300\u003csup\u003eo\u003c/sup\u003eC to convert into carbon aerogels. During carbonization, the main chains of CNF and CS underwent chemical reactions to build a robust carbon framework without degradation of their primary structures. Compared to the initial aerogel structure, the resulting carbon aerogels of different carbon aerogels (CA1 to CA4) displayed a flaky macrostructure with noticeable volume shrinkage, as depicted in \u003cstrong\u003eFigure 3\u003c/strong\u003e. The morphologies of these samples varied slightly different. CA1 and CA2 exhibiting significantly higher porosity and layered porous structure compared to CA3 and CA4. The porosity of the CA created a pathway for oil transport, while the bridges formed between the layers contributed to the integrity of the structure [21,22]. This observation aligns with the porosity measurements, suggesting that higher specific surface area and porosity lead to improved adsorption capacity.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn addition, carbonization can cause mass loss, \u003cstrong\u003eTable 2\u003c/strong\u003e outlines the mass loss of CA during carbonization at 300\u003csup\u003eo\u003c/sup\u003eC with ranging from 51% to 66%. The mass loss during carbonization was influenced by composition of the aerogel. This supported by statistical analysis, the mass ratio of CNF to CS significantly influenced the ex-tent of mass loss. This result is consistent with previous studies, which report that higher carbonization temperatures tend to increase mass loss due to the volatilization of organic components and the erosion of the carbon framework [23,24]. The findings of this study indicate that the structural properties of carbon aerogels (CAn) derived from oil palm fronds (OPF) can be tailored by adjusting the carbonization temperature and the ratio of cellulose nanofibers (CNF) to chitosan (CS). As shown in \u003cstrong\u003eTable 2\u003c/strong\u003e, the mass loss during carbonization was influenced by the composition of the aerogel [23,24].\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2.\u003c/strong\u003e Mass loss of CA after carbonization at temperature 300\u003csup\u003eo\u003c/sup\u003eC (Values in column having different letters in superscripts showed significant difference (p\u0026lt;0.05))\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"384\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eSample Code\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eBefore\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003eAfter\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003eMass loss (g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eCA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.198\u0026plusmn;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.089\u0026plusmn;0.001\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.109\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e55.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eCA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.235\u0026plusmn;0.005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.114\u0026plusmn;0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.12\u003csup\u003ea\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e51.29\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eCA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.224\u0026plusmn;0.009\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.110\u0026plusmn;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.114\u003csup\u003eab\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e51.02\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 71px;\"\u003e\n \u003cp\u003eCA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.241\u0026plusmn;0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 96px;\"\u003e\n \u003cp\u003e0.119\u0026plusmn;0.007\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 67px;\"\u003e\n \u003cp\u003e0.122\u003csup\u003ea\u003c/sup\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 54px;\"\u003e\n \u003cp\u003e50.57\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eCompared to other biomass-derived carbon aerogels, the carbon aerogels synthesized in this study demonstrate distinctive properties. For example, carbon aerogels derived from materials such as winter melon, cotton, and bamboo have shown a tendency to become brittle after carbonization, particularly at higher temperatures [2,3,8\u0026ndash;10,23]. The incorporation of chitosan into the OPF-derived aerogels in this study, however, provided structural reinforcement, as evidenced by the SEM images in \u003cstrong\u003eFigure 3\u003c/strong\u003e. The layered sheets formed by chitosan within the aerogel matrix enhanced the mechanical strength and reduced the brittleness of the carbon aerogels. This finding aligns with the work of [26], which demonstrated that chitosan could act as a reinforcing agent to improve the mechanical performance of carbon-based materials.\u003c/p\u003e\n\u003cp\u003eFrom a scientific perspective, this research contributes to the body of knowledge on the fabrication of biomass-derived carbon aerogels. The incorporation of chitosan into the carbon aerogel matrix was found to play a crucial role in improving the mechanical properties, particularly in mitigating brittleness. At 300\u003csup\u003eo\u003c/sup\u003eC, the aerogels maintain a porous, interconnected structure, facilitating oil transport and retention. This finding is in line with earlier studies that emphasize the importance of porosity and specific surface area in enhancing adsorption capacities [25,26].\u003c/p\u003e\n\u003cp\u003eThe successful fabrication of OPF-derived carbon aerogels with enhanced mechanical properties and adsorption capacity suggests that these materials can be deployed in oil/water separation applications. Their robust structure, resulting from the inclusion of chitosan, ensures that the aerogels can endure multiple cycles of oil absorption and recovery, improving their sustainability and cost-effectiveness in real-world scenarios. Additionally, the use of OPF as a raw material aligns with the principles of waste valorization, promoting a circular economy approach by converting agricultural waste into valuable functional products.\u003c/p\u003e\n\u003cp\u003e3.2. Density, porosity and surface area of CAn\u003c/p\u003e\n\u003cp\u003eThe density, porosity, and surface area of the CAn were determined to evaluate how variations in chitosan content affect their structural properties. \u003cstrong\u003eTable 3\u003c/strong\u003e presents the density and porosity values of CAn under different mass ratio of CS. A notable linear increase in density was observed with the increase in chitosan content, while a simultaneous decrease in porosity occurred. The statistical analysis conducted in this study also provides valuable insights. The finding that the porosity of CAn was primarily influenced by the ratio of CNF to chitosan, with an increase in chitosan resulting in a lower density. In contrast, the density becomes higher when affected by the CNF-chitosan ratio. This suggests that chitosan (CS) not only acts as a filler but also enhances the interaction between cellulose nanofibers (CNF), maintaining the integrity of the porous structure and making it more compressible [26]. Similar report has been reported by Zhang et al. (2021a), in their study, the addition of CS significantly enhanced the mechanical integrity of cellulose-based aerogels, resulting in a denser and more compact structure. This conclusion is consistent with the work of Han et al. (2016) and Jing et al. (2019), who emphasized the interplay between carbonization temperature, structural integrity, and adsorption capacity [25,27]. The carbonization at 300\u003csup\u003eo\u003c/sup\u003eC showed more developed carbon structure, albeit with varying degrees of mass loss and brittleness and with promising the material\u0026rsquo;s structural integrity, as seen in \u003cstrong\u003eFigure 4\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003eThe results of the Brunauer-Emmett-Teller (BET) analysis, detailed in \u003cstrong\u003eTable 4\u003c/strong\u003e, further elucidate the impact of carbonization temperature on the surface area, pore size, and pore volume of CAn. The opening of pores at elevated temperatures, which increases the available pore volume and surface area. However, this effect comes at the cost of damaging the carbon aerogel\u0026rsquo;s structure, as high temperatures can lead to structural erosion [28]. Carbonization at 300\u003csup\u003eo\u003c/sup\u003eC resulted in aerogels with a favorable balance between porosity, surface area, and mechanical stability. The results support the notion that an optimal carbonization temperature can enhance the adsorption capacity of the aerogels without compromising their structural integrity [25,28]. Congsomjit and Areeprasert (2021), also reported that elevated temperatures facilitate pore opening, thereby enhancing the surface area and pore volume.\u003c/p\u003e\n\u003cp\u003eFrom Table 4, it shown that control samples exhibited higher values for surface area, pore size, and pore volume but these values declined upon the addition of chitosan. The addition of chitosan altered the pore size distribution of the aerogels from mesoporous (control) to microporous. Despite this modification, variations in the mass ratio of the composition did not significantly affect the resulting pore diameter. Chitosan appears to graft onto the inner open pores, thereby reducing the specific surface area, total pore volume, and mesopore volume while preserving the monolithic integrity of the carbon material. The pores\u0026rsquo; configuration facilitates oil storage and further promotes oil transport through the aerogel. When compared to other biomass-derived carbon aerogels, such as bamboo and cotton, for instance, exhibited high surface areas but suffered from reduced reusability due to structural brittleness [11,13,29]. In contrast, the CAn samples in this study, particularly those carbonized at 300\u003csup\u003eo\u003c/sup\u003eC, showed a favorable balance between surface area, pore size, and mechanical strength, largely attributed to the reinforcing effect of chitosan.\u003c/p\u003e\n\u003cp id=\"_Toc153628430\"\u003e\u003cstrong\u003eTable 3.\u003c/strong\u003e Density and porosity of CAn (Values in columns with different letters in superscripts indicate significant differences, p \u0026lt; 0.05)\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eSample Code\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003eDensity\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(g/cm\u003csup\u003e3\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003ePorosity\u0026nbsp;\u003c/p\u003e\n \u003cp\u003e(%)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eControl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e0.0129\u0026plusmn;0.003\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e97.07\u0026plusmn;0.07\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eCA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e0.0134\u0026plusmn;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e97.34\u0026plusmn;0.16\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eCA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e0.0181\u0026plusmn;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e93.88\u0026plusmn;0.35\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eCA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e0.0230\u0026plusmn;0.004\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e92.78\u0026plusmn;0.55\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 108px;\"\u003e\n \u003cp\u003eCA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 144px;\"\u003e\n \u003cp\u003e0.0318\u0026plusmn;0.011\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 126px;\"\u003e\n \u003cp\u003e92.07\u0026plusmn;0.95\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4.\u0026nbsp;\u003c/strong\u003eSurface area, pore size, and total pore volume of CAn at carbonization temperatures of 300\u003csup\u003eo\u003c/sup\u003eC\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"456\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003eSample code\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 99px;\"\u003e\n \u003cp\u003eSurface Area (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003ePore size (nm)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 162px;\"\u003e\n \u003cp\u003eTotal pore volume (cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 105px;\"\u003e\n \u003cp\u003eControl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e107.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e21.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003e0.630\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003eCA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e60.31\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e2.185\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003e0.378\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003eCA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e53.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e1.723\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003e0.367\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003eCA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e47.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e1.745\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003e0.355\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 105px;\"\u003e\n \u003cp\u003eCA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 99px;\"\u003e\n \u003cp\u003e43.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003e1.736\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 162px;\"\u003e\n \u003cp\u003e0.226\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e3.3. FTIR analysis\u003c/p\u003e\n\u003cp\u003eFourier-transform infrared (FTIR) spectroscopy was employed to identify the characteristic peaks of functional groups in cellulose nanofibers (CNF), chitosan (CS), aerogel, and CAn. The FTIR spectra, as presented in \u003cstrong\u003eFigure 5\u003c/strong\u003e, exhibit distinct peaks corresponding to various chemical bonds and functional groups present in the samples. In the CNF spectra, key bands were observed at around 1160 cm\u003csup\u003e-1\u003c/sup\u003e, 1611 cm\u003csup\u003e-1\u003c/sup\u003e, and 3298 cm\u003csup\u003e-1\u003c/sup\u003e, representing C\u0026ndash;O bond vibrations, COOH bending, and O\u0026ndash;H stretching, respectively. Additional peaks at 1375 cm\u003csup\u003e-1\u003c/sup\u003e, 1427 cm\u003csup\u003e-1\u003c/sup\u003e, and 2896 cm\u003csup\u003e-1\u003c/sup\u003e correspond to the C\u0026ndash;H bending mode and characteristic C\u0026ndash;H stretching of the CH\u003csub\u003e2\u003c/sub\u003e group, which are typical of cellulose [29,30].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eFor chitosan, the characteristic peaks associated with amide functional groups appeared at 1650 cm\u003csup\u003e-1\u003c/sup\u003e (amide I), 1590 cm\u003csup\u003e-1\u003c/sup\u003e (amide II), and 1317 cm\u003csup\u003e-1\u003c/sup\u003e (amide III) [31,32]. When comparing the FTIR spectra of chitosan and CNF with that of the aerogel, a co-existence of peaks was evident, signifying the integration of both components within the aerogel structure. Specifically, the aerogel spectrum exhibited N\u0026ndash;H banding at 1638 cm\u003csup\u003e-1\u003c/sup\u003e and 1414 cm\u003csup\u003e-1\u003c/sup\u003e, as well as O\u0026ndash;H peaks at 3298 cm\u003csup\u003e-1\u003c/sup\u003e, 2896 cm\u003csup\u003e-1\u003c/sup\u003e, and 1020 cm\u003csup\u003e-1\u003c/sup\u003e. Additionally, a prominent C\u0026ndash;H asymmetric stretching peak was detected at 2910 cm\u003csup\u003e-1\u0026nbsp;\u003c/sup\u003e[27,33], confirming the successful formation of a composite network between chitosan and CNF. This bonding network is crucial for maintaining the aerogel\u0026rsquo;s structure during carbonization, thereby facilitating the development of a stable, porous material suitable for oil absorption.\u003c/p\u003e\n\u003cp\u003eNotably, after carbonization, the O\u0026ndash;H stretching vibrations at 3410 cm\u003csup\u003e-1\u003c/sup\u003e were significantly diminished, likely due to dehydration reactions occurring during the thermal treatment. This observation aligns with the expected chemical changes associated with carbonization. Additional peaks at 1595 cm\u003csup\u003e-1\u003c/sup\u003e and 1365 cm\u003csup\u003e-1\u003c/sup\u003e, corresponding to C=C vibrations of aromatic rings, were identified in the carbon aerogel spectra. These peaks suggest the formation of aromatic structures resulting from dehydrogenation and aromatization during carbonization [25,34,35]. Furthermore, bands within the 650\u0026ndash;800 cm\u003csup\u003e-1\u003c/sup\u003e range were attributed to the out-of-plane bending vibrations of unsaturated C\u0026ndash;H, indicative of the presence of aromatic compounds in the carbonized samples. This observation is consistent with the formation of a more stable aromatic carbon structure, which contributes to the aerogels\u0026rsquo; improved oil absorption properties. In comparison with studies on other biomass-derived carbon aerogels, the CAn samples in this research exhibited more pronounced aromatic characteristics, suggesting a more extensive dehydrogenation process during carbonization. This characteristic is vital for oil absorption applications, as aromatic structures enhance the hydrophobicity and oil-selective properties of the aerogels [25,34]. This finding contrasts with other studies that utilized different biomass sources, where the incorporation of additional components did not always result in clear, distinct peaks corresponding to the composite materials. For instance, in carbon aerogels derived from sugarcane bagasse, Li et al. (2021a) observed less distinct peak formations due to the complexity of the biomass source [29].\u003c/p\u003e\n\u003cp\u003eThe FTIR analysis reveals that the carbonization process not only removes surface hydroxyl groups but also induces structural changes that result in the formation of aromatic compounds. This transformation is critical in enhancing the carbon aerogels\u0026rsquo; absorption capacity.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eIn practical terms, these findings highlight the potential of OPF-derived carbon aerogels as environmentally friendly and efficient oil absorbents. The formation of aromatic structures within the aerogels, as evidenced by the FTIR analysis, contributes to their hydrophobic nature, which is essential for selective oil absorption in oil/water separation applications. The ability to fine-tune the carbonization temperature to control the aerogels\u0026rsquo; surface characteristics further emphasizes the versatility of this material for various environmental remediation purposes. Moreover, the use of OPF as the primary biomass source aligns with the principles of waste valorization and sustainability. By converting agricultural waste into functional carbon aerogels, this study provides an eco-friendly approach to mitigating oil pollution.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3.4. Wettability and selectivity of CAn\u003c/p\u003e\n\u003cp\u003eThe adsorption performance of CAn is closely linked to their hydrophobic and oleophilic properties. To evaluate the wettability of the different CAn samples, water contact angle (WCA) measurements were conducted. As shown in \u003cstrong\u003eFigure 6(a)\u003c/strong\u003e, CAn demonstrates excellent hydrophobicity, allowing water droplets to remain on the surface without spreading. This behavior indicates that the surface of CAn effectively repels water, a characteristic essential for oil/water separation applications. To further investigate the effect of composition on hydrophobicity, the WCA results for each sample are presented in \u003cstrong\u003eTable 5\u003c/strong\u003e. The WCA values for CAn samples were found to be greater than 150\u0026deg;, confirming their superhydrophobic properties. According to studies by Jing et al. (2019), Y. Q. Li et al. (2014), and T. Zhang et al. (2019), carbonization induces dehydration reactions that remove water molecules from the aerogel structure, enhancing its hydrophobic properties [3,8,26].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThe addition of CS significantly increased the WCAs, indicating enhanced hydrophobicity. This finding diverges from the results of some earlier research, where the inclusion of fillers into carbon-based materials did not markedly alter surface hydrophobicity [28]. The increase in WCA with higher CS content in may be attributed to chitosan\u0026rsquo;s ability to fill the voids in the aerogel matrix, thereby creating a denser structure during carbonization. This denser structure contributes to the material\u0026rsquo;s superhydrophobic properties by preventing water molecules from permeating the surface.\u003c/p\u003e\n\u003cp\u003eAdditionally, the selectivity of CAn towards oil and water was observed in \u003cstrong\u003eFigure 6(b)\u003c/strong\u003e. The figure illustrates that water droplets are repelled and stand on the aerogel\u0026rsquo;s surface, whereas oil droplets penetrate the structure, signifying the aerogel\u0026rsquo;s oleophilic nature. This selectivity is crucial for the aerogel\u0026rsquo;s application as an oil absorbent, as it enhances the efficiency of oil uptake while minimizing water absorption.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 5.\u003c/strong\u003e Water contact angles (WCA) of CAn at carbonization temperatures of 300\u003csup\u003eo\u003c/sup\u003eC\u0026nbsp;\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 104px;\"\u003e\n \u003cp\u003eSample code\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 113px;\"\u003e\n \u003cp\u003e300\u003csup\u003eo\u003c/sup\u003eC\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e(\u003csup\u003eo\u003c/sup\u003e)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eControl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e175.29\u0026plusmn;1.04\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e176.42\u0026plusmn;1.27\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e176.56\u0026plusmn;1.15\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e176.68\u0026plusmn;0.12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 113px;\"\u003e\n \u003cp\u003e178.30\u0026plusmn;1.11\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe wettability and selectivity analysis highlight that the CS content significantly influence the hydrophobic and oleophilic properties of CAn. The results demonstrate that increasing the CS mass ratio leads to higher WCAs, enhancing the material\u0026rsquo;s superhydrophobicity. This characteristic, combined with the aerogels\u0026rsquo; selectivity for oil over water, positions CAn as a promising candidate for oil spill cleanup applications.\u003c/p\u003e\n\u003cp\u003e3.5. Absorption capacity and reusability\u003c/p\u003e\n\u003cp\u003eThe absorption capacity and reusability of CAn were assessed using various oils, including marine fuel oil (MFO), palm oil (PO), and high-speed diesel oil (HSD). The results are summarized in \u003cstrong\u003eTable 6\u003c/strong\u003e, showing that the absorption capacity of CAn between 20\u0026ndash;76 g/g, depending on the oil type (density and viscosity) and the pore structure of the aerogel. The superhydrophobic nature of CAn, along with its interconnected porous network, facilitated oil absorption, confirming its potential for oil spill remediation. The control samples of CAn in this study exhibited the highest absorption capacities for marine fuel oil (MFO), palm oil (PO), and high-speed diesel oil (HSD) (76.27 \u0026plusmn; 1.05 g/g, 72.31 \u0026plusmn; 1.97 g/g, and 55.70 \u0026plusmn; 1.56 g/g, respectively). This observation can be attributed to the larger pore sizes and volumes of the control samples, as shown in \u003cstrong\u003eTable 4\u003c/strong\u003e, which facilitate the storage and transport of oil.\u003c/p\u003e\n\u003cp\u003eWhen compared to other carbon aerogels derived from various biomass sources, the CAn exhibit competitive absorption capacities. For instance, carbon aerogels made from sugarcane bagasse, as studied by Li et al. (2021a), showed absorption capacities in a similar range [29]. In contrast, aerogels with higher CS content demonstrated reduced absorption capacities. The absorption capacity decreased gradually with an increase in CS content, as observed in CA4, which had the lowest absorption values (28.89 \u0026plusmn; 1.53 g/g for MFO, 26.05 \u0026plusmn; 0.31 g/g for PO, and 19.26 \u0026plusmn; 1.12 g/g for HSD). \u0026nbsp;This result aligns with the findings of previous research, where increased filler content was associated with a decrease in pore volume and size, thereby limiting the material\u0026rsquo;s capacity for oil absorption [3,8,26,36]. However, the inclusion of CS in CAn improved the aerogel\u0026rsquo;s structural stability, resulting in better reusability, which is an advantage over some other biomass-based carbon aerogels that suffer from structural collapse after a few absorption cycles. The statistical analysis further confirmed that the addition of chitosan (CS) significantly affected the absorption capacity of CAn for various oils.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 6.\u003c/strong\u003e Absorption capacities of CAn for various oils (Notes: MFO = Marine Fuel Oil; PO = Palm Oil; HSD = High-Speed Diesel; Values in columns with different letters in superscripts indicate significant differences, p \u0026lt; 0.05)\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"442\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 113px;\"\u003e\n \u003cp\u003eSample code\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 329px;\"\u003e\n \u003cp\u003eAbsorption capacity (g/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 109px;\"\u003e\n \u003cp\u003eMFO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 108px;\"\u003e\n \u003cp\u003ePO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 112px;\"\u003e\n \u003cp\u003eHSD\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eControl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e76.27\u0026plusmn;1.05\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e72.31\u0026plusmn;1.97\u003csup\u003e\u0026nbsp;a\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e55.70\u0026plusmn;1.56 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e49.55\u0026plusmn;0.38\u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e69.05\u0026plusmn;1.10\u003csup\u003e\u0026nbsp;b\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e54.50\u0026plusmn;1.34 \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e46.88\u0026plusmn;1.34\u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e31.55\u0026plusmn;1.18\u003csup\u003e\u0026nbsp;c\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e33.72\u0026plusmn;1.75\u003csup\u003e\u0026nbsp;b\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e33.00\u0026plusmn;1.64\u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e29.61\u0026plusmn;1.32\u003csup\u003e\u0026nbsp;c\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e27.63\u0026plusmn;1.65 \u003csup\u003ec\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd\u003e\n \u003cp\u003eCA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e28.89\u0026plusmn;1.53\u003csup\u003ee\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e26.05\u0026plusmn;0.31\u003csup\u003e\u0026nbsp;d\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd\u003e\n \u003cp\u003e19.26\u0026plusmn;1.12 \u003csup\u003ed\u003c/sup\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 7.\u003c/strong\u003e Reusability of CAn for various oils (Notes: PO = Palm Oil; HSD = High-Speed Diesel; each sample code has triple replicates)\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\" width=\"327\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eSample code\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003ePO\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 90px;\"\u003e\n \u003cp\u003eHSD\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 147px;\"\u003e\n \u003cp\u003eControl\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eCA1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e4-5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e24-26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eCA2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e11-12\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e10-12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eCA3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e4-5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e11-10\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 147px;\"\u003e\n \u003cp\u003eCA4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e5-6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"bottom\" style=\"width: 90px;\"\u003e\n \u003cp\u003e8-9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eThe reusability of the CAn was evaluated through repeated absorption and desorption cycles, and the results are summarized in \u003cstrong\u003eTable 7\u003c/strong\u003e. Reusability is a crucial property for oil absorption materials in oil-water separation applications. Notably, MFO was not used for repeated cycles due to its thicker texture and tendency to solidify, which complicates the desorption process. From the result exhibited that control samples had the lowest reusability despite their high initial absorption capacity. This outcome suggests that while the control samples have a high capacity, their structural integrity is compromised during repeated use. Unlike some carbon aerogels documented in earlier studies, which often exhibit high initial absorption capacity but low reusability due to brittleness [25]. The CAn with CS incorporation exhibited improved reusability. However, excessive amounts of CS resulted in a decrease in absorption capacity and flexibility, as shown in the case of CA4. This observation differs from the outcomes reported in some previous research, where fillers were added without significantly impacting the absorption capacity. The densification of the pore structure in CAn due to high CS content appears to reduce oil storage space, thereby lowering its absorption capacity. Despite this reduction, the stability imparted by CS addition resulted in enhanced reusability, a feature that many traditional carbon aerogels lack.\u003c/p\u003e\n\u003cp\u003eThe absorption process of CAn is illustrated in \u003cstrong\u003eFigure 7(a)\u003c/strong\u003e and \u003cstrong\u003eFigure 7(b)\u003c/strong\u003e, where the aerogels rapidly absorb MFO and HSD, respectively, leaving clean water behind. The absorption process visualized in \u003cstrong\u003eFigure 7\u003c/strong\u003e aligns with the known properties of hydrophobic and oleophilic carbon aerogels. The rapid absorption of MFO and HSD confirms the aerogels\u0026rsquo; selectivity for oil, leaving clean water in their wake. This characteristic make CAn a competitive alternative for oil spill remediation, combining both high initial absorption capacity and the ability to withstand multiple usage cycles. This efficient absorption showcases the potential of CAn in environmental applications. The CAn samples with optimized CS content (e.g., CA2-3 and CA2-4) present a balanced performance with moderate absorption capacities and enhanced reusability. This indicates that CS not only modifies the pore structure, making it denser, but also reinforces the aerogel\u0026rsquo;s mechanical stability. These findings provide new insights into how the controlled addition of CS can improve the durability of carbon aerogels, distinguishing CAn from other biomass-derived carbon aerogels. By tuning the CS content, it is possible to fabricate aerogels with tailored properties for specific applications, offering a path forward in the development of multifunctional absorbent materials.\u003c/p\u003e\n\u003cp\u003eTo extract the absorbed oil, a 50% compression of the aerogel height was applied using an injection pump, as shown in \u003cstrong\u003eFigure 8(a)\u003c/strong\u003e. The CA structure remained stable during initial compressions, but eventually ruptured with excessive reuse, as depicted in \u003cstrong\u003eFigure 8(b)\u003c/strong\u003e. Furthermore, the comparison with other studies in \u003cstrong\u003eTable 8\u003c/strong\u003e shows that CAn exhibits a balanced performance, combining substantial absorption capacities with excellent reusability, positioning it as a versatile and sustainable material for environmental applications. The research on CAn carbon aerogels reveals a promising material that balances absorption capacity with structural reusability and chitosan content. These properties make CAn a viable candidate for oil spill remediation and other environmental applications where selective liquid absorption is critical. By showcasing the benefits of using renewable biomass and optimizing material composition, this study contributes to the ongoing efforts to develop efficient, cost-effective, and eco-friendly solutions for environmental cleanup.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 8.\u003c/strong\u003e Comparison of carbon aerogel-based materials from this study with previous research regarding oil absorption capacity and reusability\u003c/p\u003e\n\u003cdiv align=\"center\"\u003e\n \u003ctable border=\"1\" cellspacing=\"0\" cellpadding=\"0\" width=\"99%\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eMaterial\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003eCapacities Absorption\u003c/p\u003e\n \u003cp\u003e(g/g)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003eSubstance Oil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003eReusability\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003eReferences\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eCFAs from sisal leaves\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e90 \u0026ndash; 188\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003eOrganic solution, diesel oil, and soy oil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e\u0026gt;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e[35]\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eCA derived from\u003c/p\u003e\n \u003cp\u003e\u003cem\u003ePlatanus orientalis\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e30\u0026ndash;150\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003eOil/water mixtures, and water-in-kerosene emulsion\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e[37]\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eGraphene/polyvinyl alcohol/CNF carbon aerogel\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e155 \u0026ndash; 288\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003ePump oil, corn oil, and ethanol\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e\u0026gt;10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e[38]\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eCarbon aerogel from sugarcane bagasse\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e31.9 \u0026ndash; 55.02\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003eSilicone oil, edible oil, castor oil, and soybean oil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e[29]\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eAerogel from celulosa/tannic acid/castor oil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e53.2 \u0026ndash; 113.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003eOrganic solution, olive oil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e10\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e[39]\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eCarbon aerogel chitosan-citric acid\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e40 \u0026ndash; 125\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003ePolymorphic oils\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e[40]\u003c/p\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" style=\"width: 22px;\"\u003e\n \u003cp\u003eThis work\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e20 \u0026ndash; 84\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 25px;\"\u003e\n \u003cp\u003eMarine fuel oil, high speed diesel,\u003cem\u003e\u0026nbsp;\u003c/em\u003epalm oil\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 18px;\"\u003e\n \u003cp\u003e2 - 26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 14px;\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e3.6. Antimicrobial activity\u003c/p\u003e\n\u003cp\u003eThe antimicrobial activity of carbon aerogels (CA) functionalized with silver nanowires (AgNWs) was evaluated to assess their effectiveness against different bacterial strains. AgNWs were synthesized using a modified solvothermal method, where ethylene glycol acted as both the solvent and a reducing agent precursor, polyvinylpyrrolidone (PVP) served as a stabilizer, and FeCl\u003csub\u003e3\u003c/sub\u003e functioned as a reducing agent. The resulting AgNWs exhibited a diameter of approximately 100 nm and a length ranging from 10 to 50 \u0026mu;m, as shown in \u003cstrong\u003eFigure 9(a)\u003c/strong\u003e.\u003c/p\u003e\n\u003cp\u003eThe distribution of AgNWs on the three-dimensional CA structure was achieved via a dip-coating method. \u003cstrong\u003eFigure 9(b)\u003c/strong\u003e illustrates the uniform dispersion of AgNWs across each layer of the CA, indicating that the dip-coating technique is effective for incorporating AgNWs into the aerogel matrix. This uniform distribution is crucial for maximizing the antimicrobial activity of the functionalized aerogel. Additionally, the distribution of AgNWs onto the CA structure, as shown in \u003cstrong\u003eFigure 9(b)\u003c/strong\u003e, plays a crucial role in the antimicrobial performance. The dip-coating method employed in this study ensures a uniform spread of AgNWs across the aerogel layers, enhancing contact with bacterial cells and facilitating antimicrobial action. This method of AgNWs incorporation into carbon aerogels contrasts with other studies, where silver nanoparticles (AgNPs) were embedded within the aerogel matrix. Although AgNPs also exhibit antimicrobial properties, their uniform distribution is often challenging to achieve, potentially limiting their effectiveness compared to the dip-coated AgNWs [41]. To evaluate the antibacterial properties of the CA-AgNWs composites, the aerogels were loaded with different concentrations of AgNWs (0.5%, 1%, 2%, 5%, and 7%) and exposed to bacterial cells using a diffusion method. The average diameters of the clear inhibitory zones for \u003cem\u003eEscherichia coli\u003c/em\u003e, \u003cem\u003eStaphylococcus aureus\u003c/em\u003e, and \u003cem\u003eSalmonella typhi\u003c/em\u003e are presented in \u003cstrong\u003eTable 9\u003c/strong\u003e. The results show that AgNWs were more effective against Gram-negative (G-) bacteria (\u003cem\u003eE. coli\u003c/em\u003e and \u003cem\u003eS. typhi\u003c/em\u003e) than against Gram-positive (G+) bacteria (\u003cem\u003eS. aureus\u003c/em\u003e). This enhanced sensitivity to G- bacteria is likely due to the presence of lipopolysaccharides in the outer membrane of G- bacteria, which have a higher affinity for AgNWs compared to the peptidoglycan layer in G+ bacterial cell walls. Additionally, the lipopolysaccharides may trap and block the Ag+ cations, enhancing the antimicrobial effect [41,42].\u003c/p\u003e\n\u003cp\u003eIn contrast, Gram-positive bacteria, such as \u003cem\u003eS. aureus\u003c/em\u003e, have a thicker peptidoglycan layer that provides more resistance to the penetration of AgNWs. However, the present study reveals that even at lower concentrations (0.5% AgNWs), the CA-AgNWs composites exhibit significant inhibitory effects on \u003cem\u003eS. aureus\u003c/em\u003e, indicating the potential of these aerogels as broad-spectrum antimicrobial agents. This performance surpasses that of some previously reported silver-based antimicrobial materials, which often require higher concentrations to achieve similar levels of inhibition against Gram-positive bacteria [43].\u003c/p\u003e\n\u003cp\u003eFurthermore, AgNWs can interact with the membrane surface and penetrate bacterial cells. When AgNWs enter the cells via endocytosis, they are exposed to the acidic environment of cell lysosomes, which induces the production of reactive oxygen species, leading to cell membrane rupture and triggering apoptosis [43,44]. To further investigate the antibacterial mechanism, the inhibited zones were collected and examined using scanning electron microscopy (SEM). The SEM images in \u003cstrong\u003eFigure 9(c)\u003c/strong\u003e and \u003cstrong\u003eFigure 9(d)\u003c/strong\u003e display the damaged cell membranes of \u003cem\u003eE. coli\u003c/em\u003e and \u003cem\u003eS. typhi\u003c/em\u003e, respectively, confirming the antimicrobial action of AgNWs.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 9.\u003c/strong\u003e The average diameter of the clear inhibitory zone for \u003cem\u003eE. coli\u003c/em\u003e, \u003cem\u003eS. aureus\u003c/em\u003e, and \u003cem\u003eS. typhi\u003c/em\u003e at varying AgNWs concentrations\u003c/p\u003e\n\u003cdiv align=\"\"\u003e\n \u003ctable border=\"0\" cellspacing=\"0\" cellpadding=\"0\"\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" style=\"width: 104px;\"\u003e\n \u003cp\u003eSample code\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 451px;\"\u003e\n \u003cp\u003eDiameter of clear inhibitory (mm)\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e\u003cem\u003eE. coli\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e\u003cem\u003eS. aureus\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e\u003cem\u003eS. typhi\u003c/em\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eControl (-)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e6.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e5.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e5.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA-0.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e10.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e7.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e7.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA-1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e12.50\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e8.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e8.00\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA-2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e13.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e9.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e9.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA-5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e13.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e10.00\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e11.33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 104px;\"\u003e\n \u003cp\u003eCA-7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e14.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 150px;\"\u003e\n \u003cp\u003e10.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" style=\"width: 150px;\"\u003e\n \u003cp\u003e12.67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eIn practical terms, the CA-AgNWs composites offer promising applications in areas that require both adsorption and antimicrobial functions. The composite\u0026rsquo;s ability to inhibit microbial growth at relatively low AgNWs concentrations makes it a cost-effective option for water purification, where the removal of both pollutants and pathogens is essential. The effectiveness of the composites against Gram-negative bacteria, which are often more resistant to traditional disinfectants, further emphasizes their utility in water treatment processes.\u003c/p\u003e"},{"header":"4. Conclusion","content":"\u003cp\u003eThis study successfully developed carbon aerogels (CAn-x) derived from oil palm fronds (OPF) reinforced with chitosan (CS) and incorporated silver nanowires (AgNWs) for enhanced oil absorption and antimicrobial applications. The fabrication process, including the selection of optimal CNF to CS mass ratios that significantly influenced the density, porosity, surface area, and wettability of the aerogels, resulting in materials with excellent absorption capacity and selective oil absorption properties. The highest absorption capacities were observed in control samples with larger pore volumes, while the addition of chitosan enhanced the aerogel\u0026rsquo;s structural integrity and reusability.\u003c/p\u003e\u003cp\u003eThe incorporation of AgNWs into the aerogels imparted strong antimicrobial activity, particularly against Gram-negative bacteria such as \u003cem\u003eE. coli\u003c/em\u003e and \u003cem\u003eS. typhi\u003c/em\u003e. The uniform distribution of AgNWs achieved through the dip-coating method ensured effective contact with bacterial cells, as evidenced by clear inhibitory zones. These findings highlight the versatility of CA-AgNWs as multifunctional materials suitable for environmental applications, including oil spill remediation and water purification, as well as potential uses in medical fields requiring antibacterial properties.\u003c/p\u003e\u003cp\u003eThis research demonstrates the potential of renewable biomass, such as OPF, in creating high-performance, sustainable aerogels with tailored properties for various practical applications. Future work may focus on optimizing the composition and processing conditions further to maximize absorption efficiency, mechanical strength, and long-term antimicrobial performance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eDeclaration of Generative AI and AI-assisted technologies in the writing process\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDuring the preparation of this work the author(s) used ChatGPT 4o in order to correct grammar and spelling errors, enhance the language, and improve overall readability. After using this tool/service, the author(s) reviewed and edited the content as needed and take(s) full responsibility for the content of the publication.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCRediT author statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eBernadeta Ayu Widyaningrum:\u0026nbsp;\u003c/strong\u003eConceptualization, Methodology, Writing - Original Draft, Writing - Review \u0026amp; Editing, Supervision;\u003cstrong\u003e\u0026nbsp;Sudarmanto:\u0026nbsp;\u003c/strong\u003eInvestigation;\u003cstrong\u003e\u0026nbsp;Lu\u0026rsquo;lu\u0026rsquo; Qurrotul \u0026lsquo;Ain Hariri:\u0026nbsp;\u003c/strong\u003eInvestigation;\u003cstrong\u003e\u0026nbsp;Hendrawati:\u0026nbsp;\u003c/strong\u003eValidation;\u003cstrong\u003e\u0026nbsp;Riska Surya Ningrum:\u0026nbsp;\u003c/strong\u003eInvestigation, Resources;\u003cstrong\u003e\u0026nbsp;Dwi Ajias Pramasari:\u0026nbsp;\u003c/strong\u003eFormal analysis;\u003cstrong\u003e\u0026nbsp;Andrew Nosakhare Amenaghawon:\u0026nbsp;\u003c/strong\u003eValidation;\u003cstrong\u003e\u0026nbsp;Noureddine El Messaoudi:\u0026nbsp;\u003c/strong\u003eValidation;\u003cstrong\u003e\u0026nbsp;Tonni Agustiono Kurniawan:\u0026nbsp;\u003c/strong\u003eValidation;\u003cstrong\u003e\u0026nbsp;Handoko Darmokoesoemo:\u0026nbsp;\u003c/strong\u003eValidation;\u003cstrong\u003e\u0026nbsp;Heri Septya Kusuma:\u0026nbsp;\u003c/strong\u003eValidation, Writing - Review \u0026amp; Editing, Supervision.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eR.K. 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Nanomedicine 12 (2017) 3193\u0026ndash;3206. https://doi.org/10.2147/IJN.S132327.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"journal-of-porous-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jopo","sideBox":"Learn more about [Journal of Porous Materials](http://link.springer.com/journal/10934)","snPcode":"10934","submissionUrl":"https://submission.nature.com/new-submission/10934/3","title":"Journal of Porous Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Carbon aerogel, Oil palm fronds, Chitosan, Silver nanowires (AgNWs), Antimicrobial activity, Oil absorption","lastPublishedDoi":"10.21203/rs.3.rs-7269305/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7269305/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThis study explores the development of carbon aerogels (CA) derived from oil palm fronds (OPF) with chitosan (CS) reinforcement and silver nanowires (AgNWs) incorporation for oil absorption and antimicrobial applications. Cellulose nanofibrils (CNF) were extracted from OPF and mixed with CS in varying mass ratios (2:1, 1:1, 1:2, and 1:3) before undergoing freeze-drying and carbonization at temperatures of 300\u003csup\u003eo\u003c/sup\u003eC. The resulting carbon aerogels were further functionalized with AgNWs using a dip-coating technique. The CA samples were characterized for their density, porosity, surface area, and wettability. The absorption capacity for marine fuel oil, palm oil, and high-speed diesel oil ranged from 20\u0026ndash;76 g/g, influenced by the aerogel\u0026rsquo;s pore structure. The addition of CS improved the aerogel\u0026rsquo;s structural integrity, enhancing reusability over multiple absorption-desorption cycles. AgNWs loading imparted strong antimicrobial activity, particularly against Gram-negative bacteria (\u003cem\u003eE. coli\u003c/em\u003e and \u003cem\u003eS. typhi\u003c/em\u003e), as demonstrated by the agar diffusion method. The results suggest that CA-AgNWs composites exhibit excellent oil absorption performance, selectivity, and reusability, along with broad-spectrum antimicrobial properties. These findings highlight the potential of OPF-derived carbon aerogels as multifunctional materials for environmental and medical applications. This research demonstrates a sustainable approach to utilizing biomass waste for creating high-performance absorbents with tailored properties. Future work may focus on optimizing the composition and processing conditions for enhanced application efficiency.\u003c/p\u003e","manuscriptTitle":"Chitosan-Reinforced Carbon Aerogels from Oil Palm Fronds for Enhanced Oil Absorption and Silver Nanowires Loaded as Antimicrobial Activity","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-08-19 13:10:31","doi":"10.21203/rs.3.rs-7269305/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-08-25T21:57:07+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-24T03:23:32+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-20T02:55:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"94297460062157092478687534357341617611","date":"2025-08-16T18:55:50+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-16T18:14:17+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"111236431512806910879276718978153737642","date":"2025-08-13T15:55:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"155779248525701175080672267295618117575","date":"2025-08-13T15:20:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"217139857940777098096527955854193047408","date":"2025-08-13T14:01:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"271911269187212633043255154139780280638","date":"2025-08-13T13:12:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"12593274765207954730518093259180328301","date":"2025-08-13T06:39:56+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"163240238314428608431919072205891296756","date":"2025-08-12T08:07:49+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"4906598083067141626747275025168985851","date":"2025-08-11T18:09:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"52509555098300587369620857136383942751","date":"2025-08-11T16:58:28+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-11T12:56:19+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-08-04T14:49:38+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-08-04T14:49:25+00:00","index":"","fulltext":""},{"type":"submitted","content":"Journal of Porous Materials","date":"2025-08-01T08:41:48+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"journal-of-porous-materials","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"jopo","sideBox":"Learn more about [Journal of Porous Materials](http://link.springer.com/journal/10934)","snPcode":"10934","submissionUrl":"https://submission.nature.com/new-submission/10934/3","title":"Journal of Porous Materials","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"6ae493bb-89d7-4721-8464-8a94be828d6a","owner":[],"postedDate":"August 19th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-10-20T16:03:38+00:00","versionOfRecord":{"articleIdentity":"rs-7269305","link":"https://doi.org/10.1007/s10934-025-01865-z","journal":{"identity":"journal-of-porous-materials","isVorOnly":false,"title":"Journal of Porous Materials"},"publishedOn":"2025-10-19 15:58:13","publishedOnDateReadable":"October 19th, 2025"},"versionCreatedAt":"2025-08-19 13:10:31","video":"","vorDoi":"10.1007/s10934-025-01865-z","vorDoiUrl":"https://doi.org/10.1007/s10934-025-01865-z","workflowStages":[]},"version":"v1","identity":"rs-7269305","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7269305","identity":"rs-7269305","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}