Adsorption of Methylene Blue Dye from aqueous solution using low cost adsorbent: Kinetic, Isotherm Adsorption and Thermodynamic Studies

Adsorption of Methylene Blue Dye from aqueous solution using low cost adsorbent: Kinetic, Isotherm Adsorption and Thermodynamic Studies | 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 Adsorption of Methylene Blue Dye from aqueous solution using low cost adsorbent: Kinetic, Isotherm Adsorption and Thermodynamic Studies Safaa Talib Al-Asadi, Fouad Fadhil Al-Qaim This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2449414/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Fig leaf as an environmentally friendly byproduct of fruit plants, has been used for the first time to treatment of methylene blue dye. The fig leaf activated carbon (FLAC) was prepared successfully and used for adsorption of methylene blue dye (MB) purpose. The adsorbent was characterized by the Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Scanning electron microscope (SEM) and the specific surface area by the Brunauer-Emmett-Teller (BET). In the present study, initial concentrations, contact time, temperatures, pH, carbon dose, volume solution and activation agent were covered. However, the initial concentration of MB was investigated at different concentrations 20, 40, 80, 120 and 200 mg/L. pH value was examined at these values (pH3, pH7, pH8 and pH 11). When pH is 11, the adsorption efficiency of MB retains at 84.3%. To determine how well FLAC removed MB, adsorption temperatures were changed at 20, 30, 40, and 50 °C. The adsorption capacity of FLAC was determined to be 22.7 mg/g for 0.08 g and 54.9 mg/g for 0.02 g. This adsorption inclined toward the Langmuir isotherm model (R 2 >0.95), where the adsorption created a monolayer covering the surface of the adsorbent, based on the curve-fitting using the Freundlich and Langmuir isotherm models. Additionally, it was discovered that the maximum adsorption capacity (Qm) was 69.93 mg/g and the Langmuir affinity constant (KL) was 0.08 L/mg. The FLAC as low-cost adsorbents for methylene blue dye has shown good cationic dye adsorption performance. Fig leaf methylene blue adsorption activated carbon thermodynamic kinetics Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Introduction Water is the most essential element for life on earth and has a significant impact on the production of food and energy, industrial output, and the quality of our environment(Sharma and Bhattacharya 2017). Waterborne illnesses cause a considerable economic burden since they not only reduce worker productivity but also drive-up national health care expenses (Shannon et al. 2008; Sharma and Bhattacharya 2017). The production of textiles, plastic, paper, pharmaceuticals, and cosmetics all use methylene blue ( Fig. 1 ), a cationic water-soluble dye (Stewart 2016). However, due to its complex structure, natural degradation is challenging (it is nonbiodegradable), and above a certain concentration, it is toxic and carcinogenic. The removal of methylene blue from wastewater necessitates the employment of effective, environmentally friendly technology due to its presence in effluents (very apparent at modest levels of dyes 1 ppm), resulting from dying procedures or production of pharmaceuticals or cosmetics (Omer et al. 2018; Patra, Mukherjee, et al. 2021). Direct or indirect release of several sophisticated and powerful contaminants into water bodies results from domestic and industrial operations. One of these pollutants that is widely used in the textile, fabric, pharmaceutical, plastics, pulp and paper, printing, food, and printing industries is dye. The poisonous substances, acids, organics, bases, and other contaminants present in the discharged dyes have a negative impact on the natural habitats and metabolism of the aquatic and soil life (Patra, Mukherjee, et al. 2021; Patra, Nanda, et al. 2021a). Biological methods, such as anaerobic and aerobic digestion, physical methods, such as sedimentation, coagulation, filtration, ion exchange, adsorption, and reverse osmosis, and chemical methods, such as oxidation, ozonation, photochemical, and electrochemical degradation, are all used in conventional wastewater treatment to remove dyes (Patra, Nanda, et al. 2021b). Consequently, it is important to safeguard the current water resources. Insoluble chemical compounds, heavy metals, pharmaceutical micropollutants, and dyes are just a few of the contaminants that can be removed from water thanks to ongoing research efforts that have led to certain modified technologies and effective adsorbents (Huang and Shi 2014). The most effective method among them is adsorption because of its high efficiency and accessibility (Mohamed et al. 2019). The collection of solid wastes is addressed and prevented from contaminating the air and water during the natural decomposition process by converting biomass into beneficial activated carbon that is an environmentally friendly adsorbent (Singh et al. 2021). Additionally, the biomass adsorbents exhibit exceptional high surface area, substantially greater effectiveness, and a faster adsorption rate in water treatment when compared to traditional materials (L. Liu et al. 2019; Singh et al. 2021). The removal of azo dyes, and other harmful compounds from wastewater can be done with biochar nanoparticles since they are affordable, effective, and environmentally acceptable (Zhu et al. 2021). There are two different types of modification processes for biomass carbon materials now available: direct carbonization and chemical activation. Under the protection of an inert gas, high temperature carbonization of biomass carbon materials is carried out in order to break down large molecules in organic matter into smaller ones, such as carbon, water vapor, and carbon dioxide (Wu et al. 2020; Yağmur and Kaya 2021). Low specific surface area and ineffective adsorption effectiveness are drawbacks, though. The carbonization and activation processes can be finished in one step when using the chemical activation method. The use of activators such NaOH, KOH, K 2 CO 3 , H 3 PO 4 , H 2 SO 4 , and ZnCl 2 allows for the synthesis of carbon compounds with high specific surface area and large empty volume (Jawad et al. 2016; Kılıç et al. 2012; Rashid et al. 2016; Wu et al. 2020; Yağmur and Kaya 2021). Adsorption techniques are advantageous since they are economical and environmentally friendly (Gutub et al. 2013). Rice husk was altered by Liu et al. (Z. Liu et al. 2020) by chemical activation with KOH at 400°C for 30 min. and 850°C for 1 h. Due of its favorable effects on the environment and resource efficiency, modified rice husk was used to remediate wastewater that included mercury ions. Using date palm bark as the raw material, Haghbin et al. (Haghbin and Shahrak 2021) created a highly porous activated carbon using a thermal decomposition process at 400°C for 3 h followed by chemical activation with H 3 PO 4 . The materials as-prepared shown high porosity and efficient adsorption of diverse contaminants including heavy metals, dyes, and quercetin due to their large surface area and acidic functional groups on their surface (Haghbin and Shahrak 2021). Sunflower seed hulls, walnut shells, coconut shells, and corncob waste plant biomass might all be used using this straightforward process. In order to create extremely porous carbon material for the removal of phenolic compounds from aqueous medium, Prashanthakumar (Prashanthakumar et al. 2018) pyrolyzed coconut spathe in 800°C for 90 min while using KOH as an activating agent in a nitrogen atmosphere. By hydrothermally carbonizing coconut shell at 200°C for two hours and impregnating it in NaOH for four hours, Islam et al. (Islam et al. 2017) created mesoporous coconut shell activated carbon. The activated hydro-char was then heated for 1 hour at 600°C in a N 2 environment, acting as a more effective adsorbent to remove cationic dyes. KOH has been utilized extensively in comparison to other chemical activating agents to produce activated carbon that has a greater specific surface area (up to 3000 m 2 /g) and is effective at removing both organic and inorganic pollutants from wastewater (Choma et al. 2015; Li et al. 2017). Fallen leaves are a fantastic and promising option to make activated carbon. They are regarded as inexpensive adsorbents since they are abundant in nature, affordable, need little preparation, and serve as working materials as well (Faizal et al. 2019). Plant leaves are a promising choice for producing activated because of their high carbon contents, which will have a significant ecological impact (Faizal et al. 2019; Pérez-Ramírez et al. 2019). Chemical or gas activation can be used to create activated carbons from materials that contain carbon. They are the most widely utilized adsorbents because of their enormous surface area and exceptional adsorption capacity (Jawad et al. 2016). There hasn't been any research on the use of fig leaves for the adsorption of the dye methylene blue, despite the fact that many papers on the preparation of activated carbon from various less expensive and substitute agricultural wastes and byproducts with chemical activation have been published recently. Regarding the chemical synthesis of activated carbon from fig leaves with H 3 PO 4 or any other chemical agent, no investigations have been recorded. As a result, the goal of this research is to identify the ideal circumstances for producing activated carbon from fig leaf using H 3 PO 4 activation. Investigations have been done into the effects of the activation temperature, pH, carbonization agents, and other variables. To characterize the activated carbon before and after adsorption, X-ray and FTIR, instruments were used. Moreover, the obtained activated carbon was compared with other fruit leaf activated carbon. Materials And Methods Materials collection and pretreatment The fig leaves used in the current project came from waste at an Iraqi fig farm in Babylon, Iraq. After being cleaned with distilled water, fig leaves were allowed to air dry. The crushed, undersize particles from the sieving of the dried fig leaves through a 75 mesh screen were employed for the subsequent stages. Merck provided the H 3 PO 4 , H 2 SO 4 and NaOH as activation agents. Methylene blue (C 16 H 18 ClN 3 S), a basic (cationic) dye, is the adsorbate model utilized in adsorption studies; it was purchased from Dyestuffs and Chemicals Co. (china). Analytical grade chemicals were utilized exclusively; no further action was required. Activated Carbon Preparation The fig leaves (FL) were collected as crispy (i.e. dry), washed with water strongly to remove the dust and other solid matters then dried. Afterwards, the fig leaves were crushed using electric grinder and sieved for 20 mesh. A 15 mL deionized water was added in beaker contained 3 g fig leaves powder. And then, 5 mL of concentrated H 3 PO 4 , H 2 SO 4 and NaOH was added, separately and stirred continuously until all powder immersed well. It was left for 2 hours then washed with water 3–5 times to remove all acid. After that sample was dried in normal conditions for 1–2 nights. Dried powder was then carbonized in furnace at 350°C for two hours. Full experimental methodology has been presented in Fig. 2 . Flac Surface Characterization Fourier transform infrared (FTIR) spectroscopy was used to determine the presence of surface functional groups and chemical interaction for the treated fig leaf activated carbon using a Perkin Elmer Spectrum One spectrometer with universal attenuated total reflectance sampling for the range of 400–4000 cm − 1 . Cu K radiation with a wavelength of 1.54184, X-ray powder diffraction (XRD) in a Bruker D2 Phaser 2nd Gen apparatus, and a Lynxeye detector (ID mode). The adsorbent was characterized also by scanning electron microscope (SEM) and the specific surface area by the Brunauer-Emmett-Teller (BET). Adsorption Experiments A 25 mL of different concentrations of methylene blue dye solution (20, 40, 80, 120 and 200 mg/L) were mixed with 0.08 g of adsorbents and subjected to the shaker for 60 min at room temperature. The samples were centrifuged at 3000 rpm after adsorption, and the filtrates were examined. Using a UV-vis spectrophotometer and the calibration curves, the dye concentrations in the water were initially and residually measured at their highest absorbance wavelengths (650 nm). The following equations (1,2) were used to calculate the removal% and adsorption capacity of MB dye: $$\text{R}\text{%}=\frac{{\text{C}}_{0}-{C}_{t}}{{\text{C}}_{\text{f}}}\times 100 \left(1\right)$$ $$\text{Q}=\frac{{(\text{C}}_{0}-{C}_{t})}{\text{m}}\times \text{V} \left(2\right)$$ where the starting dye concentration (C 0 ) (measured in mg/L for MB), the residual concentration (C t ) was measured for the MB dye in mg/L and the final dye concentration (C f ) (measured in mg/L for MB) are given. R% is the percentage of MB dye solution removed after adsorption; Q is the adsorption capacity (mg/g) at various times; and m is the amount of FLAC (g). In order to create the necessary dye solutions, stock MB solution (1000 mg/L) was dissolved in deionized water. Adsorbent was added in 25 mL of wide spectrum of concentrations (20, 40, 80, 120 and 200 mg/L) MB solution together with 0.08 g to test the effects of contact time and initial concentration of dye on adsorption removal and adsorption capacity. According to the calibration curve, UV-vis spectrophotometer (UH4150, Hitachi) at their maximum absorption wavelengths. At a pH of (3, 7, 8, 11), with a 80 mg/L concentration of MB dye, the impact of the pH was shown. Using solutions of 1 M HCl and 1 M NaOH, the pH of the solution was changed. A 0.08 g of adsorbent was added to 25 mL of a 80 mg/L solution of MB dye at 60 min. The samples were centrifuged after adsorption then examined. Temperature has been investigated on adsorption of methylene blue dye in three different temperature values which are 20, 30, 40 and 50°C at 60 min. The concentration of MB dye was 80 mg/L and the adsorbent was 0.06 g. Different amounts of FLAC (0.02, 0.04, 0.06, 0.08 and 0.1 g) have been investigated on 80 mg/L of MB dye at 60 min. The effect of volume solution has been investigated at different values of 25, 50 and 100 mL at fixed conditions 80 mg/L MB and 0.08 g FLAC. Activation agent: three activating agents (H 3 PO 4 , H 2 SO 4 and NaOH) have been applied to select the best agent for further experiments under same conditions. Results And Discussion Fourier transform infrared spectroscopy Fourier transform infrared spectroscopy (FTIR) is the method that can be used to qualitatively assess the presence of the principal functional groups on the exterior surface of the bio-sorbent. Leaves are thought to be a biomass-rich lignocellulosic source display a lot of oxygen functional groups on its surface (Tran et al. 2017 ). However, from the searching on analysis and characterization the functional groups on the surface of waste leaf plants, it was observed the most common functional groups presents in leaf activated carbon are O-H group, C = O group, C-O group, C-H group and C = C group as shown in the previous studies (Guo et al. 2020 ; Jawad et al. 2017 ; Kushwaha et al. 2014 ). The FTIR characterization of fig leaf activated carbon (FLAC) is further performed in Fig. 3 a to study the surface functional groups of these materials. It is possible to attribute the signal at 3065 cm − 1 to vibrations of hydroxyl functional groups (Abdulhameed et al. 2021 ). The bands at 1622 cm − 1 represent the vibrational stretching of carbonyl group C = O (Abdulhameed et al. 2021 ; Jawad et al. 2020 ). A significant band at 1317 cm − 1 that was C-O band had a drop in intensity. Out of plane vibration of C-H band had observed at 781 cm − 1 . X-ray Diffraction The XRD spectrum of a FLAC sample activated in H 3 PO 4 media is shown in Fig. 3 b. A largely amorphous structure is revealed by the appearance of a broad diffraction background and the lack of a sharp peak. The outcome demonstrates that the FLAC sample has an amorphous structure, indicating that the organic components of fig leaf waste were mostly affected by the H 3 PO 4 alteration. Scanning Electron Microscopy Fig leaf was activated with H 3 PO 4 for scanning electron microscopy (SEM) evaluation, and it was found that this produced a more uniform surface and high porosity, which led to a high adsorption capacity (Fig. 3 c). The exterior surfaces of the activated carbons feature various-sized voids. The presence of these holes may facilitate the facile diffusion and trapping of large numbers of MB molecules in the pore structure of activated carbon. As a result, the use of chemical treatment helps to thoroughly clean and remove the natural colors that are present in fig leaves, freeing up the pores that they occupy and improving the fig leaves' capacity to absorb things. The pores on the surfaces of activated carbon that are created after chemical treatment are caused by the evaporation of the activating agent during carbonization, which leaves behind the ruptured surface of activated carbon with pores formerly occupied by the activating agent (Bencheikh et al. 2020 ). Nitrogen Adsorption-desorption Isotherms Nitrogen adsorption-desorption tests were carried out to describe the porous FLAC architectures (Fig. 3 d). The FLAC was estimated to have a Brunauer-Emmett-Teller (BET) specific surface area of 18.3 m 2 /g. Table 1 included a list of other porosity parameters. The high level of surface activity and vast surface area of porous carbons frequently lead to effective dye adsorption (Khangwichian et al. 2022 ). It was discovered that larger particles (327.9 nm) helped to boost adsorption capacity. Since heteroatoms can produce a redistribution of the surface charge of carbon materials, it has been demonstrated that the inclusion of heteroatoms in carbon materials greatly improves their performance. Table 1 Characteristics of FLAC adsorbent. BET surface area (m 2 /g) Langmuir surface area (m 2 /g) Total pore volume (cm 3 /g) Average particle size (nm) Micropore surface area (m 2 /g) Median pore width (nm) 18.2976 60.7756 0.0245 327.9 2.3137 1.2643 Effect of initial MB concentration UV-vis measurement is used to assess the removal% and adsorption capabilities of prepared fig leaf activated carbon. In order to study the removal efficiencies and adsorption capacities of the MB dye, the initial MB concentrations were tested at these concentration 20, 40, 80, 120 and 200 mg/L at room temperature, as shown in Fig. 4 . Research on how different adsorbents respond to the initial concentration of adsorbate has shown consistent results. In their investigation on the adsorption of methylene blue using oil palm trunk nanocrystalline cellulose, it was observed that an increase in the initial concentration of methylene blue is related to an increase in the removal effectiveness of methylene blue (Mustikaningrum et al. n.d.). In order to overcome the solid-liquid mass transfer resistance, a greater starting concentration was necessary. A vacant active site on the surface of the adsorbent that is not occupied by the adsorbate molecule will exist at very low concentrations. It can be regarded as a reduction in the system's adsorption capacity. Additionally, the active site on the surface of the adsorbent will decrease to slow down the adsorption process if an increase in initial concentration surpasses the optimal point. Figure 4 shows the graph of the fluctuation in methylene blue concentration on adsorption capacity (mg/g). In general, it may be said that the adsorption capacity increases with increasing starting concentration. The mass transfer resistance between the liquid (methylene blue) and the solid adsorbent is significantly overcome by the higher starting concentration (Al-Ghouti and Al-Absi 2020 ). The number of site FLAC might not be enough to absorb enough methylene blue molecules at high concentrations, which would lower the amount of color removed by the adsorption process. Methylene blue molecules enter the boundary layer and then diffuse to the surface of the adsorbent to start the adsorption process. The molecules continue to diffuse inside the adsorbent. Effect Of Contact Time The mass of dye adsorbed on the adsorbent and the cost of the adsorption process in wastewater treatment and water purification can both be affected by the contact time without a doubt. In a beaker filled with 25 mL of a different concentrations 20, 40, 80, 120 and 200 mg/L MB solution, 0.08 mg of FLAC was added. The mixture was then agitated strongly for a variety of times at room temperature. From Fig. 5 a, the adsorption of MB by FLAC is > 77% when the concentration was 40, 80 and 120 mg/L, respectively at contact time of 10 minute. The removal efficiency rises to > 94% when the concentration was 20, 40, 80 and 120 mg/L, respectively at contact time of 60 minute which is the equilibrium time. Adsorption capability was also taken into account and assessed, as seen in Fig. 5 b. It is clear that removal percentage and adsorption capacity have the opposite relationships. However, the lowest adsorption capacity was 6.25 mg/g at equilibrium time with MB dye concentration of 20 mg/L. While the maximum adsorption capacity was 38.9 mg/g and the MB concentration was 200 mg/L. This pattern aligns with previously published findings. According to (Izan et al. n.d.), the percentage of MB removed decreased significantly as the initial concentration of methylene blue dye was raised on magnetic char. The MB intake, however, went from 42.6 to 63.7 mg/g. Blaga et al. (Blaga et al. 2022 ) used leftover biomass from the brewing sector to examine how the initial concentration of methylene blue affected adsorption capability. He discovered that raising the MB dye concentration from 5 to 70 mg/L caused the adsorption capacity to rise from 50 to 230 mg/g. This suggests that at greater initial MB concentrations, MB cation-adsorbent surface collisions take place more frequently, increasing MB adsorption capacity (Jiang et al. 2021 ). Effect Of Temperature Figure 6 shows the change in MB adsorption removal and capacity by fig leaf activated carbon at various temperatures. The elimination efficiency of FLAC is 77.3% at room temperature, or 30°C. At 50°C, the removal efficiency increases to up to 86.4%. The mobility of the dye molecules was dynamic as the temperature rose, and there were more active sites for adsorption as well (Bharathi and Ramesh 2013 ). The adsorption capacity was increased steadily with increasing temperature from 20°C to 50°C. For MB dye adsorption, the adsorption capacity reach to 28.8 mg/g at 50°C while it was the lowest value of 22.6 mg/g at 20°C. Based on the data presented, the temperature increase causes an increase in the adsorption capacity due to the swelling of the internal structure of the adsorbent, which allows methylene blue to penetrate further (Hu et al. 2018 ). Effect Of Initial Solution Ph Figure 7 shows how the fig leaf activated carbon performs in terms of MB adsorption at various initial solution pH ranges (pH3, pH7, pH8 and pH11). With acidic conditions, the MB absorption by FLAC is comparatively low, whereas the high adsorption property is realized under basic concentration. The cationic MB dye molecules experienced electrostatic mutual repulsion with greater H + ions on the FLAC surface at lower pH levels. As we know, the OH group's active site was beneficial for adsorption of adsorbate on activated carbon surface (Islam et al. 2017 ). Therefore, at pH 3, the elimination effectiveness is just 88.5%. When the pH is increased from 3 to 7, the adsorption removal rises to 99.3%. The elimination effectiveness of FLAC is 95% when pH reaches 8 and 11. This finding was in agreement with other previous studies. According to a publication, decreased MB adsorption at pH3 may be caused by the adsorbent's predominantly protonated amino and carboxylic acid functional groups, which increase the cationic MB dye's electrostatic repulsion. When the initial pH rises till an alkaline medium, the high MB adsorption onto the adsorbents was observed (Shelke et al. 2022 ). Additionally, it was found that the proton generation competes with the MB cation for adsorption on the active FLAC sites under acidic conditions, resulting in a reduction in adsorption capacity (Nordin et al. 2021 ). The high cation exchange capacity of FLAC is probably to blame for the high MB adsorption that becomes apparent as the pH of the solution rises to a high 11. The alkaline state of the solution suggests that the adsorbent surface has more negative charges than positive ones (Murthy et al. 2020 ). The high adsorption capacity of FLAC roughly 24.5 mg/g is caused by electrostatic attraction to cationic MB due to the negative charge on its surface. Thus, it is evident that FLAC requires a neutral or basic environment in order to achieve high adsorption efficiency. Effect Of Flac Amount Figure 8 displays the results of the evaluation of the dosage of fig leaf activated carbon for the adsorption of 80 mg/L of MB dye solution at pH 7. As can be seen, the plot demonstrates that at FLAC dosages of 0.02 and 0.1 g, respectively, the adsorption efficiency of MB rose from 67.5–100%. This is brought on by the rise in the number of available empty adsorption sites and the adsorbent's surface area for adsorption (Abuzerr et al. 2018 ). High removal efficiency may result from high adsorbent dose. But as the dosage is increased, the adsorption ability decreases. It might not be enough to give negative charges for MB adsorption if the adsorbent dosage is increased further since it could change the nature of the solution (Izan et al. n.d.). As can be seen, the adsorption capacity was decreased from 33.8 to 10 mg/g when the FLAC increased from 0.02 to 0.1 g. Effect Of Solution Volume With the exception of 100 mL, FLAC exhibits great removal efficiency in the adsorption of the methylene blue dye at different volumes of solution (25, 50, and 100 mL). The highest removal rate was 99.5% with a 25 mL dosage. As the volume of the MB dye solution increases, the removal efficiency declines. At 50 mL of dye solution, the greatest adsorption capacity of 44.5 mg/g is obtained. These findings are depicted in Fig. 9 . Effect Of Activation Agent The activation process can undoubtedly influence the removal% and mass of adsorbed dye on the adsorbent. The effect of the activation process was presented in five aspects: AC1: only burn; AC2: pristine powder; AC3: impregnated in H 3 PO 4 ; AC4: impregnated in NaOH; AC5: impregnated in H 2 SO 4 on the removal% and adsorption capacity as presented in Fig. 10 . 80 mg of adsorbent was added to 25 mL of an 80 mg/L MB solution in conical flasks and shaken for 60 min at room temperature. The elimination percent of MB by AC3 is 99.6%, and the adsorption capacity is 24.9 mg/g. By testing the others, the lowest removal efficiency is 75% when pristine powder is used without any further chemical treatment. The impregnation of fig leaf powder in NaOH solution has not improved the efficiency of adsorption as much as acid did. Adsorption Isotherms The Langmuir and Freundlich models equation method was used to determine the value of the adsorption equilibrium constant (Fig. 11 ) . The Freundlich model has the lowest R 2 of the two models (0.851), but the Langmuir model has a high R 2 of 0.959. Adsorption kinetics models like the Langmuir isotherm model are frequently used to explain intricate adsorption dynamics. The maximal adsorption capacity in the current investigation was 69.93 mg/g, and the Langmuir affinity constant (KL) was 0.08 L/mg. This model accurately depicts the methylene blue adsorption by FLAC. In addition to the adsorbent's pores, the adsorption mechanism also depends on hydrogen bonds and Van der Waals interactions. The FLAC hydroxyl group, which binds the nitrogen element of methylene blue, contains hydrogen, which is what distinguishes the hydrogen bond in this adsorption method. Dipole ion interactions and electrostatic interactions are features of the Van der Waals force. An appropriate model to explain the chemical adsorption mechanism is the Langmuir isotherm one. The observable adsorption process, specifically the monolayer (Wang and Guo 2020 ), indicates this. This monolayer surface demonstrates that an active site, which can only be occupied by one molecule at a time, is responsible for carrying out the adsorption (Hasan et al. 2020 ). Other earlier investigations also supported the Langmuir isotherm model for the methylene blue adsorption procedure utilizing activated carbon from leaf waste plants (Guo et al. 2020 ; Jawad et al. 2017 ). Thermodynamic Study At 293, 303, 313, and 323 K, the impact of temperature on the adsorption of MB on FLAC adsorbent was examined. As the temperature rose from 293 to 323 K, it was found that the adsorption capacity increased from 29.2 to 30.9 mg/g. These results suggested that the MB dye may be pushed from the solution phase to the solid surface due to the increased feasibility of adsorption at higher temperatures caused by the rise in kinetic energy of dye molecules (Dural et al. 2011 ). In the study on the adsorption of MB onto FLAC, a related finding was also made. Using Eq. (3) and Eq. (4), the thermodynamic parameters change in enthalpy (∆H°), entropy (∆S°), and Gibbs free energy (∆G°) were calculated for the adsorption of MB on FLAC. $$\text{ln}\left(\frac{{C}_{s}}{{C}_{e}}\right)= \frac{{\varDelta S}^{^\circ }}{R}-\frac{{\varDelta H}^{^\circ }}{RT} \left(3\right)$$ $${\varDelta G}^{^\circ }={\varDelta H}^{^\circ }-{T\varDelta S}^{^\circ } \left(4\right)$$ where Ce is the dye's equilibrium concentration in solution (mg/L) and Cs is its equilibrium concentration in the solid phase (mg/L). Temperature is T, and gas constant R is 8.314 J/mol/K. Changes in enthalpy (kJ/mol), entropy (J/mol/K), and Gibb's free energy (kJ/mol) are denoted by the symbols ∆H ° , ∆S ° , and ∆G ° , respectively. The slope (∆H ° /R) and intercept (∆S ° /R) of the plots of ln (Cs/Ce) vs. 1/T were used to get the values of ∆H ° and ∆S ° . The coefficient of distribution is calculated using Eq. 5 which is named Kd. $${K}_{d}=\frac{{C}_{s}}{{C}_{e}} \left(5\right)$$ Table 2 displays the thermodynamic parameter values. Negative values of ∆G ° demonstrated the viability and spontaneity of the adsorption process. As the temperature rose, the values of ∆G ° fell, indicating that the adsorption was more spontaneous at low temperatures. The increase in randomness at the adsorbent-solution interface during the adsorption was described by a positive value of ∆S ° . The overall endothermic nature of the MB adsorption on FLAC is confirmed by a positive value for ∆H ° . Table 2 Thermodynamic parameters values for the adsorption of methylene blue onto FLAC at different temperatures. Temperature (K) Thermodynamic parameters Kd ∆G° (kJ/mol) ∆H° (kJ/mol) ∆S° (J/mol.K) 293 13.93 -6.47 49.3 190.33 303 28.41 -8.37 313 54.56 -10.27 323 89.9 -12.18 Kinetic study The kinetic data were investigated using the pseudo-first-order and pseudo-second-order linear models shown in equations (6) and (7), respectively (Mousavi et al. 2022 ). $$\text{log}\left({Q}_{e}-{Q}_{t}\right)=\text{log}{Q}_{e}- \frac{{K}_{ads1}}{2.303} t \left(6\right)$$ $$\frac{t}{{Q}_{t}}=\frac{1}{{K}_{ads2}\times {Q}_{e}^{2}}+\frac{1}{{Q}_{e}}t \left(7\right)$$ Where Q e and Q t are the adsorption capacities (measured in mg/g of MB adsorbed on the material) at equilibrium and any time t (min), respectively. The rate constants for the pseudo-first-order (min − 1 ) and pseudo-second-order (g/mg.min) adsorption processes are K ad1 and K ad2 , respectively. The pseudo-first-order and pseudo-second-order models, respectively, for the kinetic processes of adsorption are shown in Fig. 12 a,b. Each model's parameter values are displayed. When compared to the correlation coefficients obtained for the pseudo-first-order model, the data are demonstrated to suit the pseudo-second-order model well (R 2 = 0.9972) (Fig. 12 b). Chemisorption is therefore shown to occur because the process is dependent on the adsorbent and the concentration of the adsorbate. Selectivity Dye Adsorption In the field of selective dye adsorption and separation, earlier studies have shown that leaf waste activated carbon displayed excellent affinity for organic dyes. The heterocyclic aromatic organic compound known as the cationic MB dye is frequently utilized as a target molecule for wastewater treatment and water purification. The Fig. 13 describe the chemical composition of the methylene blue organic dye in the study of selective dye adsorption. After 60 minutes of using 0.06 g FLAC as the MB adsorbent, the color of the 25 mL 40 mg/L MB solution is almost vanished to the human sight. The cationic MB is electrostatically bound to the anionic hydroxyl groups on the FLAC surface. To demonstrate the selective dye adsorption property, Fig. 13 , UV-vis spectroscopy was used to record the solution's absorbance spectra. The MB peak is hardly discernible after adsorption. Conclusion The viability of using fig leaves as a novel, inexpensive precursor in the production of activated carbon is examined in this work (FLAC). The outcomes show that FLAC is a powerful adsorbent for the adsorption of the methylene blue dye. This study shown that H 3 PO 4 treatment could improve FLAC's ability to adsorb MB and remove it from aqueous solutions compared to other activating agents NaOH and H 2 SO 4 . The results of the adsorption experiments showed that the pseudo-second-order model best described the kinetic uptake characteristics. The overall endothermic nature of the MB adsorption on FLAC is confirmed by a positive value for ∆H ° . The negative values of ∆G ° indicate that the adsorption was more spontaneous at low temperatures. The Langmuir model, on the other hand, does a good job of describing the adsorption isotherms. I t was discovered that the maximum adsorption capacity (Qm) was 69.93 mg/g and the Langmuir affinity constant (KL) was 0.08 L/mg. The FLAC as low-cost adsorbents for methylene blue dye has shown good cationic dye adsorption performance. Declarations Acknowledgments The authors thank the College of Sciences for Women, University of Babylon, for facilitating this work. Availability of data and materials The dataset utilized/analyzed during the current study will be available from the corresponding author upon request. Funding Declaration "No funding was obtained for this study” Authors’ Contributions Safaa Talib Al-Asadi: wrote the first draft of the manuscript, did the experiments and organized the structure of the manuscript. Fouad Fadhil Al-Qaim: analysed the data and edited the final draft of the manuscript Declaration of Competing Interest The authors declare that they have no conflict of interest. All authors have read, understood, and have complied as applicable with the statement on "Ethical responsibilities of Authors" as found in the Instructions for Authors References Abdulhameed, A. S., Hum, N. N. M. F., Rangabhashiyam, S., Jawad, A. H., Wilson, L. D., Yaseen, Z. M., et al. (2021). Statistical modeling and mechanistic pathway for methylene blue dye removal by high surface area and mesoporous grass-based activated carbon using K2CO3 activator. Journal of Environmental Chemical Engineering, 9 (4), 105530. Abuzerr, S., Darwish, M., & Mahvi, A. H. (2018). Simultaneous removal of cationic methylene blue and anionic reactive red 198 dyes using magnetic activated carbon nanoparticles: equilibrium, and kinetics analysis. Water Science and Technology, 2017 (2), 534–545. Al-Ghouti, M. A., & Al-Absi, R. S. (2020). Mechanistic understanding of the adsorption and thermodynamic aspects of cationic methylene blue dye onto cellulosic olive stones biomass from wastewater. Scientific Reports, 10 (1), 1–18. Bencheikh, I., Azoulay, K., Mabrouki, J., El Hajjaji, S., Dahchour, A., Moufti, A., & Dhiba, D. (2020). The adsorptive removal of MB using chemically treated artichoke leaves: parametric, kinetic, isotherm and thermodynamic study. Scientific African, 9 , e00509. Bharathi, K. S., & Ramesh, S. T. (2013). Removal of dyes using agricultural waste as low-cost adsorbents: a review. Applied Water Science, 3 (4), 773–790. Blaga, A. C., Tanasă, A. M., Cimpoesu, R., Tataru-Farmus, R.-E., & Suteu, D. (2022). Biosorbents based on biopolymers from natural sources and food waste to retain the methylene blue dye from the aqueous medium. Polymers, 14 (13), 2728. Choma, J., Osuchowski, Ł., Dziura, A., Marszewski, M., & Jaroniec, M. (2015). Benzene and methane adsorption on ultrahigh surface area carbons prepared from sulphonated styrene divinylbenzene resin by KOH activation. Adsorption Science & Technology, 33 (6–8), 587–594. Dural, M. U., Cavas, L., Papageorgiou, S. K., & Katsaros, F. K. (2011). Methylene blue adsorption on activated carbon prepared from Posidonia oceanica (L.) dead leaves: Kinetics and equilibrium studies. Chemical Engineering Journal, 168 (1), 77–85. Faizal, A. N. M., Halim, M. H. A., & Zaini, M. A. A. (2019). Kinetics and dynamic adsorption of methylene blue by CO2-activated resorcinol formaldehyde carbon gels. Carbon letters, 29 (4), 319–326. Guo, D., Li, Y., Cui, B., Hu, M., Luo, S., Ji, B., & Liu, Y. (2020). Natural adsorption of methylene blue by waste fallen leaves of Magnoliaceae and its repeated thermal regeneration for reuse. Journal of cleaner production, 267 , 121903. Gutub, S. A., Bassyouni, M., & Abdel-Hamid, S. M. S. (2013). Dissolved solids adsorption of freshwater using synthesized bio-foam composite. Life Science Journal, 10 (2), 464–471. Haghbin, M. R., & Shahrak, M. N. (2021). Process conditions optimization for the fabrication of highly porous activated carbon from date palm bark wastes for removing pollutants from water. Powder Technology, 377 , 890–899. Hasan, R., Ying, W. J., Cheng, C. C., Jaafar, N. F., Jusoh, R., Jalil, A. A., & Setiabudi, H. D. (2020). Methylene Blue Adsorption onto Cockle Shells-Treated Banana Pith: Optimization, Isotherm, Kinetic, and Thermodynamic Studies. Indonesian Journal of Chemistry, 20 (2), 368–378. Hu, X.-S., Liang, R., & Sun, G. (2018). Super-adsorbent hydrogel for removal of methylene blue dye from aqueous solution. Journal of Materials Chemistry A, 6 (36), 17612–17624. Huang, S., & Shi, J. (2014). Monolithic macroporous carbon materials as high-performance and ultralow-cost sorbents for efficiently solving organic pollution. Industrial & Engineering Chemistry Research, 53 (12), 4888–4893. Islam, M. A., Ahmed, M. J., Khanday, W. A., Asif, M., & Hameed, B. H. (2017). Mesoporous activated coconut shell-derived hydrochar prepared via hydrothermal carbonization-NaOH activation for methylene blue adsorption. Journal of environmental management, 203 , 237–244. Izan, N. R., Zainol, M. M., Nordin, A. H., Asmadi, M., Wong, S. L., Azhar, M. A. I., & Alias, N. H. (n.d.). Removal of Methylene Blue via Adsorption using Magnetic Char Derived from Food Waste. Jawad, A. H., Bardhan, M., Islam, M. A., Islam, M. A., Syed-Hassan, S. S. A., Surip, S. N., et al. (2020). Insights into the modeling, characterization and adsorption performance of mesoporous activated carbon from corn cob residue via microwave-assisted H3PO4 activation. Surfaces and Interfaces, 21 , 100688. Jawad, A. H., Ramlah, A. R., Khudzir, I., & Sabar, S. (2017). High surface area mesoporous activated carbon developed from coconut leaf by chemical activation with H3PO4 for adsorption of methylene blue. Desalination and Water Treatment, 74 , 326–335. Jawad, A. H., Rashid, R. A., Ishak, M. A. M., & Wilson, L. D. (2016). Adsorption of methylene blue onto activated carbon developed from biomass waste by H2SO4 activation: kinetic, equilibrium and thermodynamic studies. Desalination and Water Treatment, 57 (52), 25194–25206. Jiang, W., Zhang, L., Guo, X., Yang, M., Lu, Y., Wang, Y., et al. (2021). Adsorption of cationic dye from water using an iron oxide/activated carbon magnetic composites prepared from sugarcane bagasse by microwave method. Environmental technology, 42 (3), 337–350. Khangwichian, W., Pattamasewe, S., Leesing, R., Knijnenburg, J. T. N., & Ngernyen, Y. (2022). Adsorption of cationic dye on activated carbon from hydrolyzed Dipterocarpus alatus leaves: Waste from biodiesel production. Engineering and Applied Science Research, 49 (4), 531–544. Kılıç, M., Apaydın-Varol, E., & Pütün, A. E. (2012). Preparation and surface characterization of activated carbons from Euphorbia rigida by chemical activation with ZnCl2, K2CO3, NaOH and H3PO4. Applied surface science, 261 , 247–254. Kushwaha, A. K., Gupta, N., & Chattopadhyaya, M. C. (2014). Removal of cationic methylene blue and malachite green dyes from aqueous solution by waste materials of Daucus carota. Journal of Saudi Chemical Society, 18 (3), 200–207. Li, Z., Gao, X., Wu, L., Wang, K., & Kobayashi, N. (2017). Preparation of activated carbons from poplar wood by chemical activation with KOH. Journal of Porous Materials, 24 (1), 193–202. Liu, L., Li, Y., & Fan, S. (2019). Preparation of KOH and H3PO4 modified biochar and its application in methylene blue removal from aqueous solution. Processes, 7 (12), 891. Liu, Z., Sun, Y., Xu, X., Qu, J., & Qu, B. (2020). Adsorption of Hg (II) in an aqueous solution by activated carbon prepared from rice husk using KOH activation. ACS omega, 5 (45), 29231–29242. Mohamed, G. M., Rashwan, W. E., Fathy, N. A., & Ahmed, S. A. S. (2019). Effect of nitrogen functionalization on the adsorption performance of commercial charcoal activated with phosphoric acid. Desalination and Water Treatment, 148 , 178–187. Mousavi, S. A., Mahmoudi, A., Amiri, S., Darvishi, P., & Noori, E. (2022). Methylene blue removal using grape leaves waste: optimization and modeling. Applied Water Science, 12 (5), 1–11. Murthy, T. P. K., Gowrishankar, B. S., Krishna, R. H., Chandraprabha, M. N., & Mathew, B. B. (2020). Magnetic modification of coffee husk hydrochar for adsorptive removal of methylene blue: isotherms, kinetics and thermodynamic studies. Environmental Chemistry and Ecotoxicology, 2 , 205–212. Mustikaningrum, M., Cahyono, R. B., & Yuliansyah, A. T. (n.d.). Adsorption of Methylene Blue on Nano-Crystal Cellulose of Oil Palm Trunk: Kinetic and Thermodynamic Studies. Indonesian Journal of Chemistry, 22 (4), 953–964. Nordin, A. H., Wong, S., Ngadi, N., Zainol, M. M., Abd Latif, N. A. F., & Nabgan, W. (2021). Surface functionalization of cellulose with polyethyleneimine and magnetic nanoparticles for efficient removal of anionic dye in wastewater. Journal of Environmental Chemical Engineering, 9 (1), 104639. Omer, O. S., Hussein, M. A., Hussein, B. H. M., & Mgaidi, A. (2018). Adsorption thermodynamics of cationic dyes (methylene blue and crystal violet) to a natural clay mineral from aqueous solution between 293.15 and 323.15 K. Arabian Journal of Chemistry, 11 (5), 615–623. Patra, B. R., Mukherjee, A., Nanda, S., & Dalai, A. K. (2021). Biochar production, activation and adsorptive applications: a review. Environmental Chemistry Letters, 19 (3), 2237–2259. Patra, B. R., Nanda, S., Dalai, A. K., & Meda, V. (2021a). Slow pyrolysis of agro-food wastes and physicochemical characterization of biofuel products. Chemosphere, 285 , 131431. Patra, B. R., Nanda, S., Dalai, A. K., & Meda, V. (2021b). Taguchi-based process optimization for activation of agro-food waste biochar and performance test for dye adsorption. Chemosphere, 285 , 131531. Pérez-Ramírez, E. E., de la Luz-Asunción, M., Martínez-Hernández, A. L., de la Rosa-Álvarez, G., Fernández-Tavizón, S., Salas, P., & Velasco-Santos, C. (2019). One-and two-dimensional carbon nanomaterials as adsorbents of cationic and anionic dyes from aqueous solutions. Carbon Letters, 29 (2), 155–166. Prashanthakumar, T. K. M., Kumar, S. K. A., & Sahoo, S. K. (2018). A quick removal of toxic phenolic compounds using porous carbon prepared from renewable biomass coconut spathe and exploration of new source for porous carbon materials. Journal of environmental chemical engineering, 6 (1), 1434–1442. Rashid, R. A., Jawad, A. H., Ishak, M. A. M., & Kasim, N. N. (2016). KOH-activated carbon developed from biomass waste: adsorption equilibrium, kinetic and thermodynamic studies for Methylene blue uptake. Desalination and Water Treatment, 57 (56), 27226–27236. Shannon, M. A., Bohn, P. W., Elimelech, M., Georgiadis, J. G., Mariñas, B. J., & Mayes, A. M. (2008). Science and technology for water purification in the coming decades. Nature, 452 (7185), 301–310. Sharma, S., & Bhattacharya, A. (2017). Drinking water contamination and treatment techniques. Applied water science, 7 (3), 1043–1067. Shelke, B. N., Jopale, M. K., & Kategaonkar, A. H. (2022). Exploration of biomass waste as low cost adsorbents for removal of methylene blue dye: A review. Journal of the Indian Chemical Society, 100530. Singh, A., Nanda, S., Guayaquil-Sosa, J. F., & Berruti, F. (2021). Pyrolysis of Miscanthus and characterization of value‐added bio‐oil and biochar products. The Canadian Journal of Chemical Engineering, 99 , S55–S68. Stewart, G. G. (2016). Saccharomyces species in the Production of Beer. Beverages, 2 (4), 34. Tran, H. N., You, S.-J., Nguyen, T. V., & Chao, H.-P. (2017). Insight into the adsorption mechanism of cationic dye onto biosorbents derived from agricultural wastes. Chemical Engineering Communications, 204 (9), 1020–1036. Wang, J., & Guo, X. (2020). Adsorption kinetic models: Physical meanings, applications, and solving methods. Journal of Hazardous materials, 390 , 122156. Wu, H.-Y., Chen, S. S., Liao, W., Wang, W., Jang, M.-F., Chen, W.-H., et al. (2020). Assessment of agricultural waste-derived activated carbon in multiple applications. Environmental Research, 191 , 110176. Yağmur, H. K., & Kaya, İ. (2021). Synthesis and characterization of magnetic ZnCl2-activated carbon produced from coconut shell for the adsorption of methylene blue. Journal of Molecular Structure, 1232 , 130071. Zhu, R., Yu, Q., Li, M., Zhao, H., Jin, S., Huang, Y., et al. (2021). Analysis of factors influencing pore structure development of agricultural and forestry waste-derived activated carbon for adsorption application in gas and liquid phases: A review. Journal of Environmental Chemical Engineering, 9 (5), 105905. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-2449414","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":166436456,"identity":"7aef8605-c886-43bb-b2fe-8219c1bf5139","order_by":0,"name":"Safaa Talib Al-Asadi","email":"","orcid":"","institution":"University of Babylon","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Safaa","middleName":"Talib","lastName":"Al-Asadi","suffix":""},{"id":166436457,"identity":"9b8747f8-a654-4ee1-a9e3-fbcfe199009e","order_by":1,"name":"Fouad Fadhil Al-Qaim","email":"data:image/png;base64,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","orcid":"","institution":"University of Babylon","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Fouad","middleName":"Fadhil","lastName":"Al-Qaim","suffix":""}],"badges":[],"createdAt":"2023-01-06 08:29:20","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2449414/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2449414/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":31479357,"identity":"3218a0c9-b0ba-437c-8b3f-29ab81ab4924","added_by":"auto","created_at":"2023-01-12 13:33:22","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":45808,"visible":true,"origin":"","legend":"\u003cp\u003eMethylene blue dye structure\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/5db76770b5d5ec27126f91fd.png"},{"id":31479359,"identity":"045a6c3b-6a4b-4d48-b2d1-f0f35f450206","added_by":"auto","created_at":"2023-01-12 13:33:22","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":948983,"visible":true,"origin":"","legend":"\u003cp\u003eFull experimental methodology for adsorption of methylene blue dye\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/0199fccdf87d26ae9891acb3.png"},{"id":31480249,"identity":"ff49df5f-c8fe-4a0e-9f72-8194068a57bf","added_by":"auto","created_at":"2023-01-12 13:41:22","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":326727,"visible":true,"origin":"","legend":"\u003cp\u003eSurface morphology characterization for FLAC: (a) Intensities of most common identified functional groups for FLAC using FTIR; (b)\u003cstrong\u003e \u003c/strong\u003eXRD spectrums of FLAC sample; (c) micrographs of FLAC before and after adsorption; (d) Nitrogen adsorption-desorption isotherms\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/0176961bada04b8f6cba4866.png"},{"id":31481386,"identity":"489c1bbd-d50d-4aca-b47f-c63e5c1b5320","added_by":"auto","created_at":"2023-01-12 13:49:22","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":28935,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of initial concentration (pH 7, 0.08 g adsorbent, 60 min) on the removal efficiency and adsorption capacity of MB using FLAC\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/8880081d029118b76d6e8d5b.png"},{"id":31479366,"identity":"61ee477a-195b-4b7c-b1a8-982a9c613111","added_by":"auto","created_at":"2023-01-12 13:33:22","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":63965,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of initial concentration (pH 7, 0.08 g adsorbent, 60 min) on (a) the removal efficiency and (b) adsorption capacity of MB using FLAC.\u003c/p\u003e","description":"","filename":"Figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/4515561355936c66a86773fc.png"},{"id":31481387,"identity":"13e75f05-38ab-4055-915a-41a0275d9ade","added_by":"auto","created_at":"2023-01-12 13:49:22","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":23911,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of temperature (80 mg/L MB, pH 7, 0.08 g adsorbent, 60 min) on the removal efficiency and adsorption capacity of MB using FLAC\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/8aa9ef83bbb2dbed623c2cb3.png"},{"id":31481388,"identity":"12282118-5e16-49b9-be90-7de0ebdc2d9e","added_by":"auto","created_at":"2023-01-12 13:49:22","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":23931,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of pH solution (80 mg/L MB, 0.08 g adsorbent, 60 min) on the removal efficiency and adsorption capacity of MB using FLAC\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure7.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/4e087baff5d7c054144b97f5.png"},{"id":31479361,"identity":"15aa23cc-ece3-492d-9998-a9906bb4e49d","added_by":"auto","created_at":"2023-01-12 13:33:22","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":28803,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of FLAC dosage (pH 7, 80 mg/L MB, 60 min) on the removal efficiency and adsorption capacity of MB using FLAC\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure8.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/06f05f04127ece93dd59d042.png"},{"id":31480250,"identity":"2e99eeb5-6424-4088-ae98-699a3db8065e","added_by":"auto","created_at":"2023-01-12 13:41:22","extension":"png","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":23232,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of MB solution volume \u0026nbsp;(pH 7, 80 mg/L MB, 0.08 g, \u0026nbsp;60 min) on the removal efficiency and adsorption capacity of MB using FLAC\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure9.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/93d47eb145cc83323b8edcd3.png"},{"id":31479363,"identity":"cd63ab62-7396-4dc6-8759-e3810b0bb486","added_by":"auto","created_at":"2023-01-12 13:33:22","extension":"png","order_by":10,"title":"Figure 10","display":"","copyAsset":false,"role":"figure","size":29645,"visible":true,"origin":"","legend":"\u003cp\u003eThe effect of activation agent (pH 7, 80 mg/L MB, 0.08 g adsorbent, \u0026nbsp;60 min) on the removal efficiency and adsorption capacity of MB using (AC1: only burn; AC2: pristine powder; AC3: impregnated in H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e; AC4: impregnated in NaOH; AC5: impregnated in H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e)\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure10.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/c5d9b923d2205f2daf0b05f2.png"},{"id":31480254,"identity":"6a7da4af-11a8-494c-b8cf-04ec1582fdb3","added_by":"auto","created_at":"2023-01-12 13:41:22","extension":"png","order_by":11,"title":"Figure 11","display":"","copyAsset":false,"role":"figure","size":27728,"visible":true,"origin":"","legend":"\u003cp\u003eIsotherm plots (a) Langmuir and (b) Freundlich for adsorption of MB on FLAC.\u003c/p\u003e","description":"","filename":"Figure11.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/37d86cf0f4b07a91bb9608c9.png"},{"id":31479368,"identity":"8ee21dd1-1ba1-48a2-b3d6-a4ecb8e4f880","added_by":"auto","created_at":"2023-01-12 13:33:22","extension":"png","order_by":12,"title":"Figure 12","display":"","copyAsset":false,"role":"figure","size":31380,"visible":true,"origin":"","legend":"\u003cp\u003eThe kinetics study on the adsorption processes. Plots of (a) log(\u003cem\u003eQ\u003c/em\u003e\u003csub\u003e\u003cem\u003ee\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e \u003c/em\u003e- \u003cem\u003eQ\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e) against time for pseudo-first order model, (b) t\u003cstrong\u003e/\u003c/strong\u003e\u003cem\u003e Q\u003c/em\u003e\u003csub\u003e\u003cem\u003et\u003c/em\u003e\u003c/sub\u003e\u003cem\u003e \u003c/em\u003eagainst time for pseudo-second\u003cem\u003e \u003c/em\u003eorder model\u003cem\u003e.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Figure12.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/2fa45a15510f6e661b6be7b3.png"},{"id":31479369,"identity":"8b4e73e9-2009-4b4b-811d-4d54a7b5d7c6","added_by":"auto","created_at":"2023-01-12 13:33:22","extension":"png","order_by":13,"title":"Figure 13","display":"","copyAsset":false,"role":"figure","size":159074,"visible":true,"origin":"","legend":"\u003cp\u003eAdsorption profile for MB at equilibrium state. The insert are the photograph of MB dye solution before and after adsorption by FLAC. (40 mg/L MB dye, 0.06 g adsorbent dose, and 30 min shaking time)\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"Figure13.png","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/f843f2247a75754686f98668.png"},{"id":32271067,"identity":"c65d5773-ac74-47ff-a3f1-50c411f237a2","added_by":"auto","created_at":"2023-01-31 13:59:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1880983,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2449414/v1/faa3371a-7901-429f-99ea-1cda3015160c.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Adsorption of Methylene Blue Dye from aqueous solution using low cost adsorbent: Kinetic, Isotherm Adsorption and Thermodynamic Studies","fulltext":[{"header":"Introduction","content":"\u003cp\u003eWater is the most essential element for life on earth and has a significant impact on the production of food and energy, industrial output, and the quality of our environment(Sharma and Bhattacharya 2017).\u0026nbsp;Waterborne illnesses cause a considerable economic burden since they not only reduce worker productivity but also drive-up national health care expenses\u0026nbsp;(Shannon et al. 2008; Sharma and Bhattacharya 2017). The production of textiles, plastic, paper, pharmaceuticals, and cosmetics all use methylene blue (\u003cstrong\u003eFig. 1\u003c/strong\u003e), a cationic water-soluble dye (Stewart 2016).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eHowever, due to its complex structure, natural degradation is challenging (it is nonbiodegradable), and above a certain concentration, it is toxic and carcinogenic. The removal of methylene blue from wastewater necessitates the employment of effective, environmentally friendly technology due to its presence in effluents (very apparent at modest levels of dyes 1 ppm), resulting from dying procedures or production of pharmaceuticals or cosmetics\u0026nbsp;(Omer et al. 2018; Patra, Mukherjee, et al. 2021).\u0026nbsp;Direct or indirect release of several sophisticated and powerful contaminants into water bodies results from domestic and industrial operations. One of these pollutants that is widely used in the textile, fabric, pharmaceutical, plastics, pulp and paper, printing, food, and printing industries is dye. The poisonous substances, acids, organics, bases, and other contaminants present in the discharged dyes have a negative impact on the natural habitats and metabolism of the aquatic and soil life\u0026nbsp;(Patra, Mukherjee, et al. 2021; Patra, Nanda, et al. 2021a). Biological methods, such as anaerobic and aerobic digestion, physical methods, such as sedimentation, coagulation, filtration, ion exchange, adsorption, and reverse osmosis, and chemical methods, such as oxidation, ozonation, photochemical, and electrochemical degradation, are all used in conventional wastewater treatment to remove dyes\u0026nbsp;(Patra, Nanda, et al. 2021b). Consequently, it is important to safeguard the current water resources. Insoluble chemical compounds, heavy metals, pharmaceutical micropollutants, and dyes are just a few of the contaminants that can be removed from water thanks to ongoing research efforts that have led to certain modified technologies and effective adsorbents\u0026nbsp;(Huang and Shi 2014). The most effective method among them is adsorption because of its high efficiency and accessibility\u0026nbsp;(Mohamed et al. 2019). The collection of solid wastes is addressed and prevented from contaminating the air and water during the natural decomposition process by converting biomass into beneficial activated carbon that is an environmentally friendly adsorbent\u0026nbsp;(Singh et al. 2021). Additionally, the biomass adsorbents exhibit exceptional high surface area, substantially greater effectiveness, and a faster adsorption rate in water treatment when compared to traditional materials\u0026nbsp;(L. Liu et al. 2019; Singh et al. 2021). The removal of azo dyes, and other harmful compounds from wastewater can be done with biochar nanoparticles since they are affordable, effective, and environmentally acceptable\u0026nbsp;(Zhu et al. 2021). There are two different types of modification processes for biomass carbon materials now available: direct carbonization and chemical activation. Under the protection of an inert gas, high temperature carbonization of biomass carbon materials is carried out in order to break down large molecules in organic matter into smaller ones, such as carbon, water vapor, and carbon dioxide\u0026nbsp;(Wu et al. 2020; Yağmur and Kaya 2021). Low specific surface area and ineffective adsorption effectiveness are drawbacks, though. The carbonization and activation processes can be finished in one step when using the chemical activation method. The use of activators such NaOH, KOH, K\u003csub\u003e2\u003c/sub\u003eCO\u003csub\u003e3\u003c/sub\u003e, H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e, and ZnCl\u003csub\u003e2\u003c/sub\u003e allows for the synthesis of carbon compounds with high specific surface area and large empty volume\u0026nbsp;(Jawad et al. 2016; Kılı\u0026ccedil; et al. 2012; Rashid et al. 2016; Wu et al. 2020; Yağmur and Kaya 2021). Adsorption techniques are advantageous since they are economical and environmentally friendly\u0026nbsp;(Gutub et al. 2013). Rice husk was altered by Liu et al.\u0026nbsp;(Z. Liu et al. 2020)\u0026nbsp;by chemical activation with KOH at 400\u0026deg;C for 30 min. and 850\u0026deg;C for 1 h. Due of its favorable effects on the environment and resource efficiency, modified rice husk was used to remediate wastewater that included mercury ions. Using date palm bark as the raw material, Haghbin et al.\u0026nbsp;(Haghbin and Shahrak 2021)\u0026nbsp;created a highly porous activated carbon using a thermal decomposition process at 400\u0026deg;C for 3 h followed by chemical activation with H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e. The materials as-prepared shown high porosity and efficient adsorption of diverse contaminants including heavy metals, dyes, and quercetin due to their large surface area and acidic functional groups on their surface\u0026nbsp;(Haghbin and Shahrak 2021). Sunflower seed hulls, walnut shells, coconut shells, and corncob waste plant biomass might all be used using this straightforward process. In order to create extremely porous carbon material for the removal of phenolic compounds from aqueous medium, Prashanthakumar\u0026nbsp;(Prashanthakumar et al. 2018)\u0026nbsp;pyrolyzed coconut spathe in 800\u0026deg;C for 90 min while using KOH as an activating agent in a nitrogen atmosphere. By hydrothermally carbonizing coconut shell at 200\u0026deg;C for two hours and impregnating it in NaOH for four hours, Islam et al.\u0026nbsp;(Islam et al. 2017)\u0026nbsp;created mesoporous coconut shell activated carbon. The activated hydro-char was then heated for 1 hour at 600\u0026deg;C in a N\u003csub\u003e2\u003c/sub\u003e environment, acting as a more effective adsorbent to remove cationic dyes. KOH has been utilized extensively in comparison to other chemical activating agents to produce activated carbon that has a greater specific surface area (up to 3000 m\u003csup\u003e2\u003c/sup\u003e/g) and is effective at removing both organic and inorganic pollutants from wastewater\u0026nbsp;(Choma et al. 2015; Li et al. 2017). Fallen leaves are a fantastic and promising option to make activated carbon. They are regarded as inexpensive adsorbents since they are abundant in nature, affordable, need little preparation, and serve as working materials as well\u0026nbsp;(Faizal et al. 2019). Plant leaves are a promising choice for producing activated because of their high carbon contents, which will have a significant ecological impact\u0026nbsp;(Faizal et al. 2019; P\u0026eacute;rez-Ram\u0026iacute;rez et al. 2019). Chemical or gas activation can be used to create activated carbons from materials that contain carbon. They are the most widely utilized adsorbents because of their enormous surface area and exceptional adsorption capacity\u0026nbsp;(Jawad et al. 2016).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eThere hasn\u0026apos;t been any research on the use of fig leaves for the adsorption of the dye methylene blue, despite the fact that many papers on the preparation of activated carbon from various less expensive and substitute agricultural wastes and byproducts with chemical activation have been published recently. Regarding the chemical synthesis of activated carbon from fig leaves with H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e or any other chemical agent, no investigations have been recorded. As a result, the goal of this research is to identify the ideal circumstances for producing activated carbon from fig leaf using H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e activation. Investigations have been done into the effects of the activation temperature, pH, carbonization agents, and other variables. To characterize the activated carbon before and after adsorption, X-ray and FTIR, instruments were used. Moreover, the obtained activated carbon was compared with other fruit leaf activated carbon.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cdiv class=\"Section2\" id=\"Sec3\"\u003e\n \u003ch2\u003eMaterials collection and pretreatment\u003c/h2\u003e\n \u003cp\u003eThe fig leaves used in the current project came from waste at an Iraqi fig farm in Babylon, Iraq. After being cleaned with distilled water, fig leaves were allowed to air dry. The crushed, undersize particles from the sieving of the dried fig leaves through a 75 mesh screen were employed for the subsequent stages. Merck provided the H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e and NaOH as activation agents. Methylene blue (C\u003csub\u003e16\u003c/sub\u003eH\u003csub\u003e18\u003c/sub\u003eClN\u003csub\u003e3\u003c/sub\u003eS), a basic (cationic) dye, is the adsorbate model utilized in adsorption studies; it was purchased from Dyestuffs and Chemicals Co. (china). Analytical grade chemicals were utilized exclusively; no further action was required.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eActivated Carbon Preparation\u003c/h3\u003e\n\u003cp\u003eThe fig leaves (FL) were collected as crispy (i.e. dry), washed with water strongly to remove the dust and other solid matters then dried. Afterwards, the fig leaves were crushed using electric grinder and sieved for 20 mesh. A 15 mL deionized water was added in beaker contained 3 g fig leaves powder. And then, 5 mL of concentrated H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e and NaOH was added, separately and stirred continuously until all powder immersed well. It was left for 2 hours then washed with water 3\u0026ndash;5 times to remove all acid. After that sample was dried in normal conditions for 1\u0026ndash;2 nights. Dried powder was then carbonized in furnace at 350\u0026deg;C for two hours. Full experimental methodology has been presented in Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e.\u003c/p\u003e\n\u003ch3\u003eFlac Surface Characterization\u003c/h3\u003e\n\u003cp\u003eFourier transform infrared (FTIR) spectroscopy was used to determine the presence of surface functional groups and chemical interaction for the treated fig leaf activated carbon using a Perkin Elmer Spectrum One spectrometer with universal attenuated total reflectance sampling for the range of 400\u0026ndash;4000 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Cu K radiation with a wavelength of 1.54184, X-ray powder diffraction (XRD) in a Bruker D2 Phaser 2nd Gen apparatus, and a Lynxeye detector (ID mode). The adsorbent was characterized also by scanning electron microscope (SEM) and the specific surface area by the Brunauer-Emmett-Teller (BET).\u003c/p\u003e\n\u003ch3\u003eAdsorption Experiments\u003c/h3\u003e\n\u003cp\u003eA 25 mL of different concentrations of methylene blue dye solution (20, 40, 80, 120 and 200 mg/L) were mixed with 0.08 g of adsorbents and subjected to the shaker for 60 min at room temperature. The samples were centrifuged at 3000 rpm after adsorption, and the filtrates were examined. Using a UV-vis spectrophotometer and the calibration curves, the dye concentrations in the water were initially and residually measured at their highest absorbance wavelengths (650 nm). The following equations (1,2) were used to calculate the removal% and adsorption capacity of MB dye:\u003c/p\u003e\n\u003cdiv class=\"Equation\" id=\"Equa\"\u003e\n \u003cdiv class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e$$\\text{R}\\text{%}=\\frac{{\\text{C}}_{0}-{C}_{t}}{{\\text{C}}_{\\text{f}}}\\times 100 \\left(1\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"Equation\" id=\"Equb\"\u003e\u003cdiv class=\"mathdisplay\" id=\"FileID_Equb\" name=\"EquationSource\"\u003e$$\\text{Q}=\\frac{{(\\text{C}}_{0}-{C}_{t})}{\\text{m}}\\times \\text{V} \\left(2\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cp\u003e\u003cspan style=\"text-align: inherit;\"\u003ewhere the starting dye concentration (C\u003c/span\u003e\u003csub style=\"text-align: inherit;\"\u003e0\u003c/sub\u003e\u003cspan style=\"text-align: inherit;\"\u003e) (measured in mg/L for MB), the residual concentration (C\u003c/span\u003e\u003csub style=\"text-align: inherit;\"\u003et\u003c/sub\u003e\u003cspan style=\"text-align: inherit;\"\u003e) was measured for the MB dye in mg/L and the final dye concentration (C\u003c/span\u003e\u003csub style=\"text-align: inherit;\"\u003ef\u003c/sub\u003e\u003cspan style=\"text-align: inherit;\"\u003e) (measured in mg/L for MB) are given.\u003c/span\u003e\u003c/p\u003e\u003cp\u003eR% is the percentage of MB dye solution removed after adsorption; Q is the adsorption capacity (mg/g) at various times; and m is the amount of FLAC (g). In order to create the necessary dye solutions, stock MB solution (1000 mg/L) was dissolved in deionized water. Adsorbent was added in 25 mL of wide spectrum of concentrations (20, 40, 80, 120 and 200 mg/L) MB solution together with 0.08 g to test the effects of contact time and initial concentration of dye on adsorption removal and adsorption capacity. According to the calibration curve, UV-vis spectrophotometer (UH4150, Hitachi) at their maximum absorption wavelengths. At a pH of (3, 7, 8, 11), with a 80 mg/L concentration of MB dye, the impact of the pH was shown. Using solutions of 1 M HCl and 1 M NaOH, the pH of the solution was changed. A 0.08 g of adsorbent was added to 25 mL of a 80 mg/L solution of MB dye at 60 min. The samples were centrifuged after adsorption then examined. Temperature has been investigated on adsorption of methylene blue dye in three different temperature values which are 20, 30, 40 and 50\u0026deg;C at 60 min. The concentration of MB dye was 80 mg/L and the adsorbent was 0.06 g. Different amounts of FLAC (0.02, 0.04, 0.06, 0.08 and 0.1 g) have been investigated on 80 mg/L of MB dye at 60 min. The effect of volume solution has been investigated at different values of 25, 50 and 100 mL at fixed conditions 80 mg/L MB and 0.08 g FLAC. Activation agent: three activating agents (H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e, H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e and NaOH) have been applied to select the best agent for further experiments under same conditions.\u003c/p\u003e"},{"header":"Results And Discussion","content":"\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eFourier transform infrared spectroscopy\u003c/h2\u003e \u003cp\u003eFourier transform infrared spectroscopy (FTIR) is the method that can be used to qualitatively assess the presence of the principal functional groups on the exterior surface of the bio-sorbent. Leaves are thought to be a biomass-rich lignocellulosic source display a lot of oxygen functional groups on its surface (Tran et al. \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). However, from the searching on analysis and characterization the functional groups on the surface of waste leaf plants, it was observed the most common functional groups presents in leaf activated carbon are O-H group, C\u0026thinsp;=\u0026thinsp;O group, C-O group, C-H group and C\u0026thinsp;=\u0026thinsp;C group as shown in the previous studies (Guo et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Jawad et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Kushwaha et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2014\u003c/span\u003e). The FTIR characterization of fig leaf activated carbon (FLAC) is further performed in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ea to study the surface functional groups of these materials. It is possible to attribute the signal at 3065 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e to vibrations of hydroxyl functional groups (Abdulhameed et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The bands at 1622 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e represent the vibrational stretching of carbonyl group C\u0026thinsp;=\u0026thinsp;O (Abdulhameed et al. \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Jawad et al. \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). A significant band at 1317 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e that was C-O band had a drop in intensity. Out of plane vibration of C-H band had observed at 781 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eX-ray Diffraction\u003c/h3\u003e\n\u003cp\u003eThe XRD spectrum of a FLAC sample activated in H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e media is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003eb. A largely amorphous structure is revealed by the appearance of a broad diffraction background and the lack of a sharp peak. The outcome demonstrates that the FLAC sample has an amorphous structure, indicating that the organic components of fig leaf waste were mostly affected by the H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e alteration.\u003c/p\u003e\n\u003ch3\u003eScanning Electron Microscopy\u003c/h3\u003e\n\u003cp\u003eFig leaf was activated with H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e for scanning electron microscopy (SEM) evaluation, and it was found that this produced a more uniform surface and high porosity, which led to a high adsorption capacity (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ec). The exterior surfaces of the activated carbons feature various-sized voids. The presence of these holes may facilitate the facile diffusion and trapping of large numbers of MB molecules in the pore structure of activated carbon. As a result, the use of chemical treatment helps to thoroughly clean and remove the natural colors that are present in fig leaves, freeing up the pores that they occupy and improving the fig leaves' capacity to absorb things. The pores on the surfaces of activated carbon that are created after chemical treatment are caused by the evaporation of the activating agent during carbonization, which leaves behind the ruptured surface of activated carbon with pores formerly occupied by the activating agent (Bencheikh et al. \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e2020\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eNitrogen Adsorption-desorption Isotherms\u003c/h3\u003e\n\u003cp\u003eNitrogen adsorption-desorption tests were carried out to describe the porous FLAC architectures (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003ed). The FLAC was estimated to have a Brunauer-Emmett-Teller (BET) specific surface area of 18.3 m\u003csup\u003e2\u003c/sup\u003e/g. Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e included a list of other porosity parameters. The high level of surface activity and vast surface area of porous carbons frequently lead to effective dye adsorption (Khangwichian et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). It was discovered that larger particles (327.9 nm) helped to boost adsorption capacity. Since heteroatoms can produce a redistribution of the surface charge of carbon materials, it has been demonstrated that the inclusion of heteroatoms in carbon materials greatly improves their performance.\u003c/p\u003e \u003cp\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\u003eCharacteristics of FLAC adsorbent.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"No\" id=\"Taba\" border=\"1\"\u003e \u003ccolgroup cols=\"6\"\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 \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBET surface area (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eLangmuir surface area\u003c/p\u003e \u003cp\u003e(m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eTotal pore volume (cm\u003csup\u003e3\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eAverage particle size (nm)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMicropore surface area (m\u003csup\u003e2\u003c/sup\u003e/g)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMedian pore width (nm)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e18.2976\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e60.7756\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.0245\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e327.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2.3137\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.2643\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eEffect of initial MB concentration\u003c/b\u003e \u003c/p\u003e \u003cp\u003eUV-vis measurement is used to assess the removal% and adsorption capabilities of prepared fig leaf activated carbon. In order to study the removal efficiencies and adsorption capacities of the MB dye, the initial MB concentrations were tested at these concentration 20, 40, 80, 120 and 200 mg/L at room temperature, as shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e.\u003c/p\u003e \u003cp\u003eResearch on how different adsorbents respond to the initial concentration of adsorbate has shown consistent results. In their investigation on the adsorption of methylene blue using oil palm trunk nanocrystalline cellulose, it was observed that an increase in the initial concentration of methylene blue is related to an increase in the removal effectiveness of methylene blue (Mustikaningrum et al. n.d.). In order to overcome the solid-liquid mass transfer resistance, a greater starting concentration was necessary. A vacant active site on the surface of the adsorbent that is not occupied by the adsorbate molecule will exist at very low concentrations.\u003c/p\u003e \u003cp\u003eIt can be regarded as a reduction in the system's adsorption capacity. Additionally, the active site on the surface of the adsorbent will decrease to slow down the adsorption process if an increase in initial concentration surpasses the optimal point. Figure\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e shows the graph of the fluctuation in methylene blue concentration on adsorption capacity (mg/g). In general, it may be said that the adsorption capacity increases with increasing starting concentration. The mass transfer resistance between the liquid (methylene blue) and the solid adsorbent is significantly overcome by the higher starting concentration (Al-Ghouti and Al-Absi \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The number of site FLAC might not be enough to absorb enough methylene blue molecules at high concentrations, which would lower the amount of color removed by the adsorption process. Methylene blue molecules enter the boundary layer and then diffuse to the surface of the adsorbent to start the adsorption process. The molecules continue to diffuse inside the adsorbent.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eEffect Of Contact Time\u003c/h3\u003e\n\u003cp\u003eThe mass of dye adsorbed on the adsorbent and the cost of the adsorption process in wastewater treatment and water purification can both be affected by the contact time without a doubt. In a beaker filled with 25 mL of a different concentrations 20, 40, 80, 120 and 200 mg/L MB solution, 0.08 mg of FLAC was added. The mixture was then agitated strongly for a variety of times at room temperature. From Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003ea, the adsorption of MB by FLAC is \u0026gt;\u0026thinsp;77% when the concentration was 40, 80 and 120 mg/L, respectively at contact time of 10 minute. The removal efficiency rises to \u0026gt;\u0026thinsp;94% when the concentration was 20, 40, 80 and 120 mg/L, respectively at contact time of 60 minute which is the equilibrium time.\u003c/p\u003e \u003cp\u003eAdsorption capability was also taken into account and assessed, as seen in Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003eb. It is clear that removal percentage and adsorption capacity have the opposite relationships. However, the lowest adsorption capacity was 6.25 mg/g at equilibrium time with MB dye concentration of 20 mg/L. While the maximum adsorption capacity was 38.9 mg/g and the MB concentration was 200 mg/L. This pattern aligns with previously published findings. According to (Izan et al. n.d.), the percentage of MB removed decreased significantly as the initial concentration of methylene blue dye was raised on magnetic char. The MB intake, however, went from 42.6 to 63.7 mg/g. Blaga et al. (Blaga et al. \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) used leftover biomass from the brewing sector to examine how the initial concentration of methylene blue affected adsorption capability. He discovered that raising the MB dye concentration from 5 to 70 mg/L caused the adsorption capacity to rise from 50 to 230 mg/g. This suggests that at greater initial MB concentrations, MB cation-adsorbent surface collisions take place more frequently, increasing MB adsorption capacity (Jiang et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eEffect Of Temperature\u003c/h3\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e6\u003c/span\u003e shows the change in MB adsorption removal and capacity by fig leaf activated carbon at various temperatures. The elimination efficiency of FLAC is 77.3% at room temperature, or 30\u0026deg;C. At 50\u0026deg;C, the removal efficiency increases to up to 86.4%. The mobility of the dye molecules was dynamic as the temperature rose, and there were more active sites for adsorption as well (Bharathi and Ramesh \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). The adsorption capacity was increased steadily with increasing temperature from 20\u0026deg;C to 50\u0026deg;C. For MB dye adsorption, the adsorption capacity reach to 28.8 mg/g at 50\u0026deg;C while it was the lowest value of 22.6 mg/g at 20\u0026deg;C. Based on the data presented, the temperature increase causes an increase in the adsorption capacity due to the swelling of the internal structure of the adsorbent, which allows methylene blue to penetrate further (Hu et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2018\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eEffect Of Initial Solution Ph\u003c/h3\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig7\" class=\"InternalRef\"\u003e7\u003c/span\u003e shows how the fig leaf activated carbon performs in terms of MB adsorption at various initial solution pH ranges (pH3, pH7, pH8 and pH11). With acidic conditions, the MB absorption by FLAC is comparatively low, whereas the high adsorption property is realized under basic concentration. The cationic MB dye molecules experienced electrostatic mutual repulsion with greater H\u003csup\u003e+\u003c/sup\u003e ions on the FLAC surface at lower pH levels. As we know, the OH group's active site was beneficial for adsorption of adsorbate on activated carbon surface (Islam et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Therefore, at pH 3, the elimination effectiveness is just 88.5%. When the pH is increased from 3 to 7, the adsorption removal rises to 99.3%. The elimination effectiveness of FLAC is 95% when pH reaches 8 and 11. This finding was in agreement with other previous studies. According to a publication, decreased MB adsorption at pH3 may be caused by the adsorbent's predominantly protonated amino and carboxylic acid functional groups, which increase the cationic MB dye's electrostatic repulsion. When the initial pH rises till an alkaline medium, the high MB adsorption onto the adsorbents was observed (Shelke et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAdditionally, it was found that the proton generation competes with the MB cation for adsorption on the active FLAC sites under acidic conditions, resulting in a reduction in adsorption capacity (Nordin et al. \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2021\u003c/span\u003e). The high cation exchange capacity of FLAC is probably to blame for the high MB adsorption that becomes apparent as the pH of the solution rises to a high 11. The alkaline state of the solution suggests that the adsorbent surface has more negative charges than positive ones (Murthy et al. \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). The high adsorption capacity of FLAC roughly 24.5 mg/g is caused by electrostatic attraction to cationic MB due to the negative charge on its surface. Thus, it is evident that FLAC requires a neutral or basic environment in order to achieve high adsorption efficiency.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eEffect Of Flac Amount\u003c/h3\u003e\n\u003cp\u003eFigure\u0026nbsp;\u003cspan refid=\"Fig8\" class=\"InternalRef\"\u003e8\u003c/span\u003e displays the results of the evaluation of the dosage of fig leaf activated carbon for the adsorption of 80 mg/L of MB dye solution at pH 7. As can be seen, the plot demonstrates that at FLAC dosages of 0.02 and 0.1 g, respectively, the adsorption efficiency of MB rose from 67.5\u0026ndash;100%. This is brought on by the rise in the number of available empty adsorption sites and the adsorbent's surface area for adsorption (Abuzerr et al. \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). High removal efficiency may result from high adsorbent dose. But as the dosage is increased, the adsorption ability decreases. It might not be enough to give negative charges for MB adsorption if the adsorbent dosage is increased further since it could change the nature of the solution (Izan et al. n.d.). As can be seen, the adsorption capacity was decreased from 33.8 to 10 mg/g when the FLAC increased from 0.02 to 0.1 g.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eEffect Of Solution Volume\u003c/h3\u003e\n\u003cp\u003eWith the exception of 100 mL, FLAC exhibits great removal efficiency in the adsorption of the methylene blue dye at different volumes of solution (25, 50, and 100 mL). The highest removal rate was 99.5% with a 25 mL dosage. As the volume of the MB dye solution increases, the removal efficiency declines. At 50 mL of dye solution, the greatest adsorption capacity of 44.5 mg/g is obtained. These findings are depicted in Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e9\u003c/span\u003e.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eEffect Of Activation Agent\u003c/h3\u003e\n\u003cp\u003eThe activation process can undoubtedly influence the removal% and mass of adsorbed dye on the adsorbent. The effect of the activation process was presented in five aspects: AC1: only burn; AC2: pristine powder; AC3: impregnated in H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e; AC4: impregnated in NaOH; AC5: impregnated in H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e on the removal% and adsorption capacity as presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e10\u003c/span\u003e. 80 mg of adsorbent was added to 25 mL of an 80 mg/L MB solution in conical flasks and shaken for 60 min at room temperature. The elimination percent of MB by AC3 is 99.6%, and the adsorption capacity is 24.9 mg/g. By testing the others, the lowest removal efficiency is 75% when pristine powder is used without any further chemical treatment. The impregnation of fig leaf powder in NaOH solution has not improved the efficiency of adsorption as much as acid did.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eAdsorption Isotherms\u003c/h3\u003e\n\u003cp\u003eThe Langmuir and Freundlich models equation method was used to determine the value of the adsorption equilibrium constant (Fig.\u0026nbsp;\u003cspan refid=\"Fig11\" class=\"InternalRef\"\u003e11\u003c/span\u003e\u003cb\u003e)\u003c/b\u003e. The Freundlich model has the lowest R\u003csup\u003e2\u003c/sup\u003e of the two models (0.851), but the Langmuir model has a high R\u003csup\u003e2\u003c/sup\u003e of 0.959. Adsorption kinetics models like the Langmuir isotherm model are frequently used to explain intricate adsorption dynamics. The maximal adsorption capacity in the current investigation was 69.93 mg/g, and the Langmuir affinity constant (KL) was 0.08 L/mg. This model accurately depicts the methylene blue adsorption by FLAC. In addition to the adsorbent's pores, the adsorption mechanism also depends on hydrogen bonds and Van der Waals interactions. The FLAC hydroxyl group, which binds the nitrogen element of methylene blue, contains hydrogen, which is what distinguishes the hydrogen bond in this adsorption method. Dipole ion interactions and electrostatic interactions are features of the Van der Waals force. An appropriate model to explain the chemical adsorption mechanism is the Langmuir isotherm one. The observable adsorption process, specifically the monolayer (Wang and Guo \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), indicates this. This monolayer surface demonstrates that an active site, which can only be occupied by one molecule at a time, is responsible for carrying out the adsorption (Hasan et al. \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Other earlier investigations also supported the Langmuir isotherm model for the methylene blue adsorption procedure utilizing activated carbon from leaf waste plants (Guo et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Jawad et al. \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2017\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eThermodynamic Study\u003c/h3\u003e\n\u003cp\u003eAt 293, 303, 313, and 323 K, the impact of temperature on the adsorption of MB on FLAC adsorbent was examined. As the temperature rose from 293 to 323 K, it was found that the adsorption capacity increased from 29.2 to 30.9 mg/g. These results suggested that the MB dye may be pushed from the solution phase to the solid surface due to the increased feasibility of adsorption at higher temperatures caused by the rise in kinetic energy of dye molecules (Dural et al. \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). In the study on the adsorption of MB onto FLAC, a related finding was also made. Using Eq.\u0026nbsp;(3) and Eq.\u0026nbsp;(4), the thermodynamic parameters change in enthalpy (∆H\u0026deg;), entropy (∆S\u0026deg;), and Gibbs free energy (∆G\u0026deg;) were calculated for the adsorption of MB on FLAC.\u003cdiv id=\"Equc\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equc\" name=\"EquationSource\"\u003e\n$$\\text{ln}\\left(\\frac{{C}_{s}}{{C}_{e}}\\right)= \\frac{{\\varDelta S}^{^\\circ }}{R}-\\frac{{\\varDelta H}^{^\\circ }}{RT} \\left(3\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equd\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equd\" name=\"EquationSource\"\u003e\n$${\\varDelta G}^{^\\circ }={\\varDelta H}^{^\\circ }-{T\\varDelta S}^{^\\circ } \\left(4\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003ewhere Ce is the dye's equilibrium concentration in solution (mg/L) and Cs is its equilibrium concentration in the solid phase (mg/L). Temperature is T, and gas constant R is 8.314 J/mol/K. Changes in enthalpy (kJ/mol), entropy (J/mol/K), and Gibb's free energy (kJ/mol) are denoted by the symbols ∆H\u003csup\u003e\u0026deg;\u003c/sup\u003e, ∆S\u003csup\u003e\u0026deg;\u003c/sup\u003e, and ∆G\u003csup\u003e\u0026deg;\u003c/sup\u003e, respectively. The slope (∆H\u003csup\u003e\u0026deg;\u003c/sup\u003e/R) and intercept (∆S\u003csup\u003e\u0026deg;\u003c/sup\u003e/R) of the plots of ln (Cs/Ce) vs. 1/T were used to get the values of ∆H\u003csup\u003e\u0026deg;\u003c/sup\u003e and ∆S\u003csup\u003e\u0026deg;\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe coefficient of distribution is calculated using Eq.\u0026nbsp;5 which is named Kd.\u003cdiv id=\"Eque\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Eque\" name=\"EquationSource\"\u003e\n$${K}_{d}=\\frac{{C}_{s}}{{C}_{e}} \\left(5\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eTable\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e displays the thermodynamic parameter values. Negative values of ∆G\u003csup\u003e\u0026deg;\u003c/sup\u003e demonstrated the viability and spontaneity of the adsorption process. As the temperature rose, the values of ∆G\u003csup\u003e\u0026deg;\u003c/sup\u003e fell, indicating that the adsorption was more spontaneous at low temperatures. The increase in randomness at the adsorbent-solution interface during the adsorption was described by a positive value of ∆S\u003csup\u003e\u0026deg;\u003c/sup\u003e. The overall endothermic nature of the MB adsorption on FLAC is confirmed by a positive value for ∆H\u003csup\u003e\u0026deg;\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eThermodynamic parameters values for the adsorption of methylene blue onto FLAC at different temperatures.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTemperature (K)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"4\" nameend=\"c5\" namest=\"c2\"\u003e \u003cp\u003eThermodynamic parameters\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eKd\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003e∆G\u0026deg; (kJ/mol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e∆H\u0026deg; (kJ/mol)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003e∆S\u0026deg; (J/mol.K)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e293\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13.93\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-6.47\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e49.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e190.33\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e303\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e28.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-8.37\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e313\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e54.56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-10.27\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e323\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e89.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e-12.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cb\u003eKinetic study\u003c/b\u003e \u003c/p\u003e \u003cp\u003eThe kinetic data were investigated using the pseudo-first-order and pseudo-second-order linear models shown in equations (6) and (7), respectively (Mousavi et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2022\u003c/span\u003e).\u003cdiv id=\"Equf\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equf\" name=\"EquationSource\"\u003e\n$$\\text{log}\\left({Q}_{e}-{Q}_{t}\\right)=\\text{log}{Q}_{e}- \\frac{{K}_{ads1}}{2.303} t \\left(6\\right)$$\u003c/div\u003e\u003c/div\u003e\u003cdiv id=\"Equg\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equg\" name=\"EquationSource\"\u003e\n$$\\frac{t}{{Q}_{t}}=\\frac{1}{{K}_{ads2}\\times {Q}_{e}^{2}}+\\frac{1}{{Q}_{e}}t \\left(7\\right)$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eWhere Q\u003csub\u003ee\u003c/sub\u003e and Q\u003csub\u003et\u003c/sub\u003e are the adsorption capacities (measured in mg/g of MB adsorbed on the material) at equilibrium and any time t (min), respectively. The rate constants for the pseudo-first-order (min\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and pseudo-second-order (g/mg.min) adsorption processes are K\u003csub\u003ead1\u003c/sub\u003e and K\u003csub\u003ead2\u003c/sub\u003e, respectively. The pseudo-first-order and pseudo-second-order models, respectively, for the kinetic processes of adsorption are shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003ea,b. Each model's parameter values are displayed. When compared to the correlation coefficients obtained for the pseudo-first-order model, the data are demonstrated to suit the pseudo-second-order model well (R\u003csup\u003e2\u003c/sup\u003e\u0026thinsp;=\u0026thinsp;0.9972) (Fig.\u0026nbsp;\u003cspan refid=\"Fig12\" class=\"InternalRef\"\u003e12\u003c/span\u003eb). Chemisorption is therefore shown to occur because the process is dependent on the adsorbent and the concentration of the adsorbate.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eSelectivity Dye Adsorption\u003c/h3\u003e\n\u003cp\u003eIn the field of selective dye adsorption and separation, earlier studies have shown that leaf waste activated carbon displayed excellent affinity for organic dyes. The heterocyclic aromatic organic compound known as the cationic MB dye is frequently utilized as a target molecule for wastewater treatment and water purification. The Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e describe the chemical composition of the methylene blue organic dye in the study of selective dye adsorption. After 60 minutes of using 0.06 g FLAC as the MB adsorbent, the color of the 25 mL 40 mg/L MB solution is almost vanished to the human sight. The cationic MB is electrostatically bound to the anionic hydroxyl groups on the FLAC surface. To demonstrate the selective dye adsorption property, Fig.\u0026nbsp;\u003cspan refid=\"Fig13\" class=\"InternalRef\"\u003e13\u003c/span\u003e, UV-vis spectroscopy was used to record the solution's absorbance spectra. The MB peak is hardly discernible after adsorption.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe viability of using fig leaves as a novel, inexpensive precursor in the production of activated carbon is examined in this work (FLAC). The outcomes show that FLAC is a powerful adsorbent for the adsorption of the methylene blue dye. This study shown that H\u003csub\u003e3\u003c/sub\u003ePO\u003csub\u003e4\u003c/sub\u003e treatment could improve FLAC's ability to adsorb MB and remove it from aqueous solutions compared to other activating agents NaOH and H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e. The results of the adsorption experiments showed that the pseudo-second-order model best described the kinetic uptake characteristics. The overall endothermic nature of the MB adsorption on FLAC is confirmed by a positive value for ∆H\u003csup\u003e\u0026deg;\u003c/sup\u003e. The negative values of ∆G\u003csup\u003e\u0026deg;\u003c/sup\u003e indicate that the adsorption was more spontaneous at low temperatures. The Langmuir model, on the other hand, does a good job of describing the adsorption isotherms. \u003cb\u003eI\u003c/b\u003et was discovered that the maximum adsorption capacity (Qm) was 69.93 mg/g and the Langmuir affinity constant (KL) was 0.08 L/mg. The FLAC as low-cost adsorbents for methylene blue dye has shown good cationic dye adsorption performance.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors thank the College of Sciences for Women, University of Babylon, for facilitating this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe dataset utilized/analyzed during the current study will be available from the corresponding author upon request.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Declaration\u003c/strong\u003e \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\"No funding was obtained for this study”\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSafaa Talib Al-Asadi: wrote the first draft of the manuscript, did the experiments and organized the structure of the manuscript. Fouad Fadhil Al-Qaim: analysed the data and edited the final draft of the manuscript\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDeclaration of Competing Interest\u0026nbsp;\u003c/strong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;\u0026nbsp;The authors declare that they have no conflict of interest.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eAll authors have read, understood, and have complied as applicable with the statement on \"Ethical responsibilities of Authors\" as found in the Instructions for Authors\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003e\u003cspan\u003eAbdulhameed, A. S., Hum, N. N. M. F., Rangabhashiyam, S., Jawad, A. H., Wilson, L. D., Yaseen, Z. M., et al. (2021). Statistical modeling and mechanistic pathway for methylene blue dye removal by high surface area and mesoporous grass-based activated carbon using K2CO3 activator. Journal of Environmental Chemical Engineering, \u003cem\u003e9\u003c/em\u003e(4), 105530.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eAbuzerr, S., Darwish, M., \u0026amp; Mahvi, A. H. (2018). Simultaneous removal of cationic methylene blue and anionic reactive red 198 dyes using magnetic activated carbon nanoparticles: equilibrium, and kinetics analysis. Water Science and Technology, \u003cem\u003e2017\u003c/em\u003e(2), 534\u0026ndash;545.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eAl-Ghouti, M. A., \u0026amp; Al-Absi, R. S. (2020). Mechanistic understanding of the adsorption and thermodynamic aspects of cationic methylene blue dye onto cellulosic olive stones biomass from wastewater. Scientific Reports, \u003cem\u003e10\u003c/em\u003e(1), 1\u0026ndash;18.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eBencheikh, I., Azoulay, K., Mabrouki, J., El Hajjaji, S., Dahchour, A., Moufti, A., \u0026amp; Dhiba, D. (2020). The adsorptive removal of MB using chemically treated artichoke leaves: parametric, kinetic, isotherm and thermodynamic study. Scientific African, \u003cem\u003e9\u003c/em\u003e, e00509.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eBharathi, K. S., \u0026amp; Ramesh, S. T. (2013). Removal of dyes using agricultural waste as low-cost adsorbents: a review. Applied Water Science, \u003cem\u003e3\u003c/em\u003e(4), 773\u0026ndash;790.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eBlaga, A. C., Tanasă, A. M., Cimpoesu, R., Tataru-Farmus, R.-E., \u0026amp; Suteu, D. (2022). Biosorbents based on biopolymers from natural sources and food waste to retain the methylene blue dye from the aqueous medium. Polymers, \u003cem\u003e14\u003c/em\u003e(13), 2728.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eChoma, J., Osuchowski, Ł., Dziura, A., Marszewski, M., \u0026amp; Jaroniec, M. (2015). Benzene and methane adsorption on ultrahigh surface area carbons prepared from sulphonated styrene divinylbenzene resin by KOH activation. Adsorption Science \u0026amp; Technology, \u003cem\u003e33\u003c/em\u003e(6\u0026ndash;8), 587\u0026ndash;594.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eDural, M. U., Cavas, L., Papageorgiou, S. K., \u0026amp; Katsaros, F. K. (2011). Methylene blue adsorption on activated carbon prepared from Posidonia oceanica (L.) dead leaves: Kinetics and equilibrium studies. Chemical Engineering Journal, \u003cem\u003e168\u003c/em\u003e(1), 77\u0026ndash;85.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eFaizal, A. N. M., Halim, M. H. A., \u0026amp; Zaini, M. A. A. (2019). Kinetics and dynamic adsorption of methylene blue by CO2-activated resorcinol formaldehyde carbon gels. Carbon letters, \u003cem\u003e29\u003c/em\u003e(4), 319\u0026ndash;326.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eGuo, D., Li, Y., Cui, B., Hu, M., Luo, S., Ji, B., \u0026amp; Liu, Y. (2020). Natural adsorption of methylene blue by waste fallen leaves of Magnoliaceae and its repeated thermal regeneration for reuse. Journal of cleaner production, \u003cem\u003e267\u003c/em\u003e, 121903.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eGutub, S. A., Bassyouni, M., \u0026amp; Abdel-Hamid, S. M. S. (2013). Dissolved solids adsorption of freshwater using synthesized bio-foam composite. Life Science Journal, \u003cem\u003e10\u003c/em\u003e(2), 464\u0026ndash;471.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eHaghbin, M. R., \u0026amp; Shahrak, M. N. (2021). Process conditions optimization for the fabrication of highly porous activated carbon from date palm bark wastes for removing pollutants from water. Powder Technology, \u003cem\u003e377\u003c/em\u003e, 890\u0026ndash;899.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eHasan, R., Ying, W. J., Cheng, C. C., Jaafar, N. F., Jusoh, R., Jalil, A. A., \u0026amp; Setiabudi, H. D. (2020). Methylene Blue Adsorption onto Cockle Shells-Treated Banana Pith: Optimization, Isotherm, Kinetic, and Thermodynamic Studies. Indonesian Journal of Chemistry, \u003cem\u003e20\u003c/em\u003e(2), 368\u0026ndash;378.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eHu, X.-S., Liang, R., \u0026amp; Sun, G. (2018). Super-adsorbent hydrogel for removal of methylene blue dye from aqueous solution. Journal of Materials Chemistry A, \u003cem\u003e6\u003c/em\u003e(36), 17612\u0026ndash;17624.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eHuang, S., \u0026amp; Shi, J. (2014). Monolithic macroporous carbon materials as high-performance and ultralow-cost sorbents for efficiently solving organic pollution. Industrial \u0026amp; Engineering Chemistry Research, \u003cem\u003e53\u003c/em\u003e(12), 4888\u0026ndash;4893.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eIslam, M. A., Ahmed, M. J., Khanday, W. A., Asif, M., \u0026amp; Hameed, B. H. (2017). Mesoporous activated coconut shell-derived hydrochar prepared via hydrothermal carbonization-NaOH activation for methylene blue adsorption. Journal of environmental management, \u003cem\u003e203\u003c/em\u003e, 237\u0026ndash;244.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eIzan, N. R., Zainol, M. M., Nordin, A. H., Asmadi, M., Wong, S. L., Azhar, M. A. I., \u0026amp; Alias, N. H. (n.d.). Removal of Methylene Blue via Adsorption using Magnetic Char Derived from Food Waste.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eJawad, A. H., Bardhan, M., Islam, M. A., Islam, M. A., Syed-Hassan, S. S. A., Surip, S. N., et al. (2020). Insights into the modeling, characterization and adsorption performance of mesoporous activated carbon from corn cob residue via microwave-assisted H3PO4 activation. Surfaces and Interfaces, \u003cem\u003e21\u003c/em\u003e, 100688.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eJawad, A. H., Ramlah, A. R., Khudzir, I., \u0026amp; Sabar, S. (2017). High surface area mesoporous activated carbon developed from coconut leaf by chemical activation with H3PO4 for adsorption of methylene blue. Desalination and Water Treatment, \u003cem\u003e74\u003c/em\u003e, 326\u0026ndash;335.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eJawad, A. H., Rashid, R. A., Ishak, M. A. M., \u0026amp; Wilson, L. D. (2016). Adsorption of methylene blue onto activated carbon developed from biomass waste by H2SO4 activation: kinetic, equilibrium and thermodynamic studies. Desalination and Water Treatment, \u003cem\u003e57\u003c/em\u003e(52), 25194\u0026ndash;25206.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eJiang, W., Zhang, L., Guo, X., Yang, M., Lu, Y., Wang, Y., et al. (2021). Adsorption of cationic dye from water using an iron oxide/activated carbon magnetic composites prepared from sugarcane bagasse by microwave method. Environmental technology, \u003cem\u003e42\u003c/em\u003e(3), 337\u0026ndash;350.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eKhangwichian, W., Pattamasewe, S., Leesing, R., Knijnenburg, J. T. N., \u0026amp; Ngernyen, Y. (2022). Adsorption of cationic dye on activated carbon from hydrolyzed Dipterocarpus alatus leaves: Waste from biodiesel production. Engineering and Applied Science Research, \u003cem\u003e49\u003c/em\u003e(4), 531\u0026ndash;544.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eKılı\u0026ccedil;, M., Apaydın-Varol, E., \u0026amp; P\u0026uuml;t\u0026uuml;n, A. E. (2012). Preparation and surface characterization of activated carbons from Euphorbia rigida by chemical activation with ZnCl2, K2CO3, NaOH and H3PO4. Applied surface science, \u003cem\u003e261\u003c/em\u003e, 247\u0026ndash;254.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eKushwaha, A. K., Gupta, N., \u0026amp; Chattopadhyaya, M. C. (2014). Removal of cationic methylene blue and malachite green dyes from aqueous solution by waste materials of Daucus carota. Journal of Saudi Chemical Society, \u003cem\u003e18\u003c/em\u003e(3), 200\u0026ndash;207.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eLi, Z., Gao, X., Wu, L., Wang, K., \u0026amp; Kobayashi, N. (2017). Preparation of activated carbons from poplar wood by chemical activation with KOH. Journal of Porous Materials, \u003cem\u003e24\u003c/em\u003e(1), 193\u0026ndash;202.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eLiu, L., Li, Y., \u0026amp; Fan, S. (2019). Preparation of KOH and H3PO4 modified biochar and its application in methylene blue removal from aqueous solution. Processes, \u003cem\u003e7\u003c/em\u003e(12), 891.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eLiu, Z., Sun, Y., Xu, X., Qu, J., \u0026amp; Qu, B. (2020). Adsorption of Hg (II) in an aqueous solution by activated carbon prepared from rice husk using KOH activation. ACS omega, \u003cem\u003e5\u003c/em\u003e(45), 29231\u0026ndash;29242.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMohamed, G. M., Rashwan, W. E., Fathy, N. A., \u0026amp; Ahmed, S. A. S. (2019). Effect of nitrogen functionalization on the adsorption performance of commercial charcoal activated with phosphoric acid. Desalination and Water Treatment, \u003cem\u003e148\u003c/em\u003e, 178\u0026ndash;187.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMousavi, S. A., Mahmoudi, A., Amiri, S., Darvishi, P., \u0026amp; Noori, E. (2022). Methylene blue removal using grape leaves waste: optimization and modeling. Applied Water Science, \u003cem\u003e12\u003c/em\u003e(5), 1\u0026ndash;11.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMurthy, T. P. K., Gowrishankar, B. S., Krishna, R. H., Chandraprabha, M. N., \u0026amp; Mathew, B. B. (2020). Magnetic modification of coffee husk hydrochar for adsorptive removal of methylene blue: isotherms, kinetics and thermodynamic studies. Environmental Chemistry and Ecotoxicology, \u003cem\u003e2\u003c/em\u003e, 205\u0026ndash;212.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eMustikaningrum, M., Cahyono, R. B., \u0026amp; Yuliansyah, A. T. (n.d.). Adsorption of Methylene Blue on Nano-Crystal Cellulose of Oil Palm Trunk: Kinetic and Thermodynamic Studies. Indonesian Journal of Chemistry, \u003cem\u003e22\u003c/em\u003e(4), 953\u0026ndash;964.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eNordin, A. H., Wong, S., Ngadi, N., Zainol, M. M., Abd Latif, N. A. F., \u0026amp; Nabgan, W. (2021). Surface functionalization of cellulose with polyethyleneimine and magnetic nanoparticles for efficient removal of anionic dye in wastewater. Journal of Environmental Chemical Engineering, \u003cem\u003e9\u003c/em\u003e(1), 104639.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eOmer, O. S., Hussein, M. A., Hussein, B. H. M., \u0026amp; Mgaidi, A. (2018). Adsorption thermodynamics of cationic dyes (methylene blue and crystal violet) to a natural clay mineral from aqueous solution between 293.15 and 323.15 K. Arabian Journal of Chemistry, \u003cem\u003e11\u003c/em\u003e(5), 615\u0026ndash;623.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003ePatra, B. R., Mukherjee, A., Nanda, S., \u0026amp; Dalai, A. K. (2021). Biochar production, activation and adsorptive applications: a review. Environmental Chemistry Letters, \u003cem\u003e19\u003c/em\u003e(3), 2237\u0026ndash;2259.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003ePatra, B. R., Nanda, S., Dalai, A. K., \u0026amp; Meda, V. (2021a). Slow pyrolysis of agro-food wastes and physicochemical characterization of biofuel products. Chemosphere, \u003cem\u003e285\u003c/em\u003e, 131431.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003ePatra, B. R., Nanda, S., Dalai, A. K., \u0026amp; Meda, V. (2021b). Taguchi-based process optimization for activation of agro-food waste biochar and performance test for dye adsorption. Chemosphere, \u003cem\u003e285\u003c/em\u003e, 131531.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eP\u0026eacute;rez-Ram\u0026iacute;rez, E. E., de la Luz-Asunci\u0026oacute;n, M., Mart\u0026iacute;nez-Hern\u0026aacute;ndez, A. L., de la Rosa-\u0026Aacute;lvarez, G., Fern\u0026aacute;ndez-Taviz\u0026oacute;n, S., Salas, P., \u0026amp; Velasco-Santos, C. (2019). One-and two-dimensional carbon nanomaterials as adsorbents of cationic and anionic dyes from aqueous solutions. Carbon Letters, \u003cem\u003e29\u003c/em\u003e(2), 155\u0026ndash;166.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003ePrashanthakumar, T. K. M., Kumar, S. K. A., \u0026amp; Sahoo, S. K. (2018). A quick removal of toxic phenolic compounds using porous carbon prepared from renewable biomass coconut spathe and exploration of new source for porous carbon materials. Journal of environmental chemical engineering, \u003cem\u003e6\u003c/em\u003e(1), 1434\u0026ndash;1442.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eRashid, R. A., Jawad, A. H., Ishak, M. A. M., \u0026amp; Kasim, N. N. (2016). KOH-activated carbon developed from biomass waste: adsorption equilibrium, kinetic and thermodynamic studies for Methylene blue uptake. Desalination and Water Treatment, \u003cem\u003e57\u003c/em\u003e(56), 27226\u0026ndash;27236.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eShannon, M. A., Bohn, P. W., Elimelech, M., Georgiadis, J. G., Mari\u0026ntilde;as, B. J., \u0026amp; Mayes, A. M. (2008). Science and technology for water purification in the coming decades. Nature, \u003cem\u003e452\u003c/em\u003e(7185), 301\u0026ndash;310.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eSharma, S., \u0026amp; Bhattacharya, A. (2017). Drinking water contamination and treatment techniques. Applied water science, \u003cem\u003e7\u003c/em\u003e(3), 1043\u0026ndash;1067.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eShelke, B. N., Jopale, M. K., \u0026amp; Kategaonkar, A. H. (2022). Exploration of biomass waste as low cost adsorbents for removal of methylene blue dye: A review. Journal of the Indian Chemical Society, 100530.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eSingh, A., Nanda, S., Guayaquil-Sosa, J. F., \u0026amp; Berruti, F. (2021). Pyrolysis of Miscanthus and characterization of value‐added bio‐oil and biochar products. The Canadian Journal of Chemical Engineering, \u003cem\u003e99\u003c/em\u003e, S55\u0026ndash;S68.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eStewart, G. G. (2016). Saccharomyces species in the Production of Beer. Beverages, \u003cem\u003e2\u003c/em\u003e(4), 34.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eTran, H. N., You, S.-J., Nguyen, T. V., \u0026amp; Chao, H.-P. (2017). Insight into the adsorption mechanism of cationic dye onto biosorbents derived from agricultural wastes. Chemical Engineering Communications, \u003cem\u003e204\u003c/em\u003e(9), 1020\u0026ndash;1036.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eWang, J., \u0026amp; Guo, X. (2020). Adsorption kinetic models: Physical meanings, applications, and solving methods. Journal of Hazardous materials, \u003cem\u003e390\u003c/em\u003e, 122156.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eWu, H.-Y., Chen, S. S., Liao, W., Wang, W., Jang, M.-F., Chen, W.-H., et al. (2020). Assessment of agricultural waste-derived activated carbon in multiple applications. Environmental Research, \u003cem\u003e191\u003c/em\u003e, 110176.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eYağmur, H. K., \u0026amp; Kaya, İ. (2021). Synthesis and characterization of magnetic ZnCl2-activated carbon produced from coconut shell for the adsorption of methylene blue. Journal of Molecular Structure, \u003cem\u003e1232\u003c/em\u003e, 130071.\u003c/span\u003e\u003c/li\u003e\n \u003cli\u003e\u003cspan\u003eZhu, R., Yu, Q., Li, M., Zhao, H., Jin, S., Huang, Y., et al. (2021). Analysis of factors influencing pore structure development of agricultural and forestry waste-derived activated carbon for adsorption application in gas and liquid phases: A review. Journal of Environmental Chemical Engineering, \u003cem\u003e9\u003c/em\u003e(5), 105905.\u003c/span\u003e\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Fig leaf, methylene blue, adsorption, activated carbon, thermodynamic, kinetics","lastPublishedDoi":"10.21203/rs.3.rs-2449414/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2449414/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eFig leaf as an environmentally friendly byproduct of fruit plants, has been used for the first time to treatment of methylene blue dye. The fig leaf activated carbon (FLAC) was prepared successfully and used for adsorption of methylene blue dye (MB) purpose. The adsorbent was characterized by the Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD),\u0026nbsp; Scanning electron microscope (SEM) and the specific surface area by the Brunauer-Emmett-Teller (BET). In the present study, initial concentrations, contact time, temperatures, pH, carbon dose, volume solution and activation agent were covered. However, the initial concentration of MB was investigated at different concentrations 20, 40, 80, 120 and 200 mg/L. pH value was examined at these values (pH3, pH7, pH8 and pH 11). When pH is 11, the adsorption efficiency of MB retains at 84.3%. To determine how well FLAC removed MB, adsorption temperatures were changed at 20, 30, 40, and 50 °C. The adsorption capacity of FLAC was determined to be 22.7 mg/g for 0.08 g and 54.9 mg/g for 0.02 g. This adsorption inclined toward the Langmuir isotherm model (R\u003csup\u003e2\u003c/sup\u003e\u0026gt;0.95), where the adsorption created a monolayer covering the surface of the adsorbent, based on the curve-fitting using the Freundlich and Langmuir isotherm models. Additionally, it was discovered that the maximum adsorption capacity (Qm) was 69.93 mg/g and the Langmuir affinity constant (KL) was 0.08 L/mg. The FLAC as low-cost adsorbents for methylene blue dye has shown good cationic dye adsorption performance.\u003c/p\u003e","manuscriptTitle":"Adsorption of Methylene Blue Dye from aqueous solution using low cost adsorbent: Kinetic, Isotherm Adsorption and Thermodynamic Studies","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-01-12 13:33:17","doi":"10.21203/rs.3.rs-2449414/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"33352220-973d-4dc1-b064-523fd8b776e4","owner":[],"postedDate":"January 12th, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-02-03T07:59:31+00:00","versionOfRecord":[],"versionCreatedAt":"2023-01-12 13:33:17","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2449414","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2449414","identity":"rs-2449414","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}