Spectroscopic Approaches for Structural Analysis of Extracted Chitosan Generated from Chitin Deacetylated for Escalated Periods

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N. Ghanem, M. I. Marzouk, Magda Tawfik, Samir Eskander This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-5723322/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 16 Jul, 2025 Read the published version in BMC Chemistry → Version 1 posted 8 You are reading this latest preprint version Abstract A conventional chemical method was applied for the extraction of chitosan (CH) from shrimp shell wastes (SSWs) in three stages: 1. Demineralization: SSWs were treated with HCl to remove minerals. 2. Deproteinization: NaOH was used to eliminate proteins from the demineralization shells. 3: Deacetylation: The chitin (CT) obtained from stage 2 was converted to chitosan in alkaline medium using NaOH. This study aims to demonstrate the impact of varying deacetylation times on chitosan surface morphology, elemental composition, thermal resistance, structural configuration, and deacetylation degree (DD). Variable techniques including UV-visible spectroscopy, Fourier Transformed Infra-Red (FTIR-ATR), Thermogravimetry (TG/DTG), Scanning Electron Microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) analyses were employed to analyze how increased deacetylation periods affect the characterization of the products. The FTIR spectra showed a notable similarity between all extracted chitosan processed with increasing deacetylation time and the commercial one. Moreover, the results revealed that all the extracted chitosan samples acquired DD values, based on FTIR-ATR analysis, are comparable to that of commercial ones i.e. 79.54%, 78.23%, 74.81%, and 76.56% for deacetylated times of 22 hrs, 30 hrs, 36 hrs, and 40 hours, respectively are comparable to that of the commercial chitosan (76.1%). Furthermore, the EDX analysis confirms that the extracted chitosan is non-toxic product, making it suitable for various applications, including biological and medical uses. shrimp shell waste chemical extraction of chitosan degree of deacetylation FTIR-ART SEM-EDX UV-Vis. TG DTG DSC Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction The name chitosan designates a chain of deacetylated chitin macromolecules with diverse molecular weight, viscosity, and degree of deacetylation, (DD) (40–99%). Chitosan is a linear polyamine with a number of amino groups that are accessible for chemical reactions with acids or other active groups [ 1 ]. It is a cationic amino polysaccharide and it has extensive applications in many fields: in medicine, biomedical and pharmaceutical industries e.g. fibers, membranes, and artificial organs; in biology; in agriculture; in the environment; in the field of cosmetic production alike body creams, lotions, additives for the hair; in addition to some foodstuff manufactures e.g. binder, gelling agent, thickener; antimicrobial agents and antioxidants fabrication are among others [ 2 , 3 ]. Chitosan has great attention among researchers, due to its efficient scavenger capability for heavy metals [ 4 – 7 ]. Chitosan beads can be applied, also, to sorb radionuclides e.g. radiocesium, radiocobalt …etc., from radioactive aqueous solution streams [ 8 , 9 ]. Different practices have been applied to extract chitin and consequently chitosan, but the furthermost widespread is the chemical processing route [ 10 ]. Many analysing tools are used to characterize the chitosan products, among all those methods: Fourier Transformed Infra-Red, Thermal analyses, and Scanning Electron Microscope prove to be a very beneficial tool since it was applied to reveal the amount and the nature of chemical fractions generated from various composite materials in addition to DD evaluation [ 11 – 13 ]. In this study all-chitosan products extracted from shrimp shell wastes are subjected to characterization using UV-visible spectroscopy, Fourier Transformed Infra-Red (FTIR-ATR) examination, Thermogravimetry, Derivative thermogravimetry (TG/DTG), Differential scanning calorimetric analyses (DSC), Scanning Electron Microscope (SEM), and Energy-dispersive X-ray spectroscopy (EDX) analysis. Those tools were applied to evaluate the impact of increasing deacetylation periods on the physico-chemical properties of the obtained chitosan and to compare it to the commercial chitosan purchased from Sigma Reagent Co. Material and Methods Materials Fresh samples of shrimp shells were obtained from the wastes of processing discards and collected from a local shrimp market in Egypt. The shrimp shell wastes (SSWs) under consideration, were selected, packed in plastic bags, and stored at (-10°C) before and during transportation to the laboratory. The SSWs were washed with water and soap several times, boiled with water and soap for 10 min, rewashed, and then dried in an oven at 90°C. Finally, the clean dried shells were ground to the predetermined smallest mesh sizes. Commercial chitosan with 76% deacetylation degree was purchased from Sigma Reagent Co., Ltd. It was used as a reference for comparison with the extracted one. All other used chemicals in this study were of analytical grade and applied without any further purification. Methods Extraction of chitosan Demineralization step (1) The demineralization of ground shrimp shells was carried out at room temperature (25 ± 5°C) using 1M hydrochloric acid until the production of carbon dioxide (CO 2 ) gas was completely stopped. The demineralized ground shells were filtered under suction through a Buchner funnel with coarse porosity filter paper Whatman No. 40, and the residue was washed with distilled water several times till it reached neutral pH (6.5 ± 0.5). Finally, the solid material was dried in a drying oven at 90 ºC for constant mass. The chemical reaction for this step can be illustrated as follows: the minerals in the shells (mainly calcium carbonate) are decomposed into calcium chloride along with the discharge of carbon dioxide, by hydrochloric acid at room temperature. 2HCl + CaCO → CaCl + HO + CO ↑.........(1) Deproteinization step (2) Deproteinization of the demineralized SSWs was carried out using 1.0 M sodium hydroxide solution (NaOH) (1:10 mass/v ratio of demineralized SSWs to NaOH) at (100 ± 5) °C for one hour. This step was repeated several times. The absence of protein was indicated by the absence of a pale pink color in the medium. The product was rinsed with distilled water up to neutral pH. At this stage, perfectly white chitin is isolated. Any traces of pigment colors can be removed by applying a mild oxidizing agent for chitin (KMnO 4 + oxalic acid + H 2 SO 4 ), washed with distilled water, and then dried in an oven at 90°C (9). Deacetylation of chitin step (3) The deacetylation of chitin can be highly facilitated by steeping it for 48 hours in concentrated sodium hydroxide solution, (40% by mass) at room temperature (25 ± 5) °C before heating. Then, the container used for deacetylation was subjected to reflux at (100 ± 5) °C, at normal pressure, and for up to 40 hours; the reaction was accompanied by drastic degradation of the chitin-producing chitosan. The obtained chitosan was washed with distilled water to a neutral pH and oven-dried at 90°C for constant mass [ 9 , 10 ]. Evaluation and Analyses Fourier-Transform Infrared Spectroscopy (FTIR-ATR) The most interested functional groups of the prepared samples were determined by Fourier-Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR), Bruker Vertex 80V with resolution 4cm -1 in the range of 4000–400cm -1 . The sample was examined directly in a powder form without preparation. Scanning Electron Microscope and Energy-dispersive X-ray spectroscopy (SEM-EDX) The surface morphology of shrimp shell, chitin, commercial chitosan, and extracted chitosan acquired from chitin deacetylation for increasing periods were investigated by applying the surfaces of small pieces to field-emission scanning electron microscope (FE-SEM, Quanta FEG-250) at 20Kv after covering with a thin layer of gold. The samples were subjected to the dry tiny pieces of the various samples to gold plating in S150 a Sputter Coater Edwards (England). Predetermined samples were subjected to analysis by Energy-dispersive X-ray spectroscopy (EDAX) AMETEK Materials Analysis Division. Ultraviolet / Visible spectroscopy UV/visible absorption spectra (200 to 900 nm) were recorded by Cary-100 UV-2450 spectrophotometer using a slit width of 2 nm. A pair of quartz cuvettes with a path length of 1cm was employed for this purpose. Samples of commercial chitosan and extracted chitosan acquired from chitin deacetylation for increasing periods were dissolved in 0.1% acetic acid solution and absorbance spectra of the samples were measured at above selected wavelength ranges. Duplicate measurements were made for each sample and the average values were reported. Thermal analysis Thermogravimetric (TGA) Differential Thermogravimetric (DTG) and Differential scanning calorimetric analyses (DSC) were performed using Setaram KECHNOLOGIES Themys one (France). Each analysis was performed in a platinum cell under a nitrogen atmosphere at a flow rate of 20 ml/min starting from room temperature up to 600 o C at a heating rate of 10 o C /min. Results and Discussion The chitosan can successfully be prepared from the deacetylation of chitin which is extracted chemically from shrimp shells. The quality and physicochemical properties of prepared chitosan are varied widely with the quality of shrimp shell, chitin, and methods of preparation. The production of chitosan is based on the deacetylation reaction of chitin i.e. of hydrolysis of chitins’ acetamide groups. This is associated, also, with the splitting of chitin’s acetyl group with the formation of an amino group. Additionally, the deacetylation reaction can be associated with a concurrent rupture of the polymer glycosidic bonds. FTIR -ATR Analysis Infrared spectroscopy is one of the highly interesting and extensively applied analytical practices, based on the vibrations of the atoms of a molecule, to study the chemical configuration of materials. Moreover, FT-IR analysis can be used to evaluate the degree of deacetylation of chitosan extracted from shrimp shell waste. In this study, FTIR-ATR analyses were performed systematically for commercial chitosan (CHC) for comparison, besides for the extracted chitosan acquired from chitin following increasing deacetylation periods i.e.: 22 hrs (CHI); 30 hrs (CHII); 36 hrs (CHIII), and 40 hrs (CHIV) under the same analyses’ conditions, to evaluate the impact of escalation of deacetylation periods on DD % and their spectra. The results obtained are presented in Figure (1) and Table (1). Figure (1) It is clear from Figure (1) that, a very wide absorption peak between 3362 − 3286 cm − 1 that signify stretching vibration of the hydroxyl group (-OH), an amine group (-NH 2 ), and hydrogen bonding in the extracted chitosan (CHI-CHIV). Those are very comparable to the spectrum peak of commercial one, i.e., 3361 − 3283 cm − 1 (CHC). It is worth to notify that, not any of the presented spectra in Figure (1), even the commercial chitosan, showed any sharp peak close to 3500 cm − 1 , which corroborates that the hydroxyl groups in positions C2 and C6 of the chitosan are engaged in intra- and intermolecular hydrogen bonds [ 14 ]. The band assigned close to 2879 cm − 1 can be attributed to -C-H stretching vibration, even when there is a shift of this peak according to the acid utilized in the extraction of the chitosan. The deproteinization step of chitosan can be prove by the decline in the -CH signal absorbance intensity and non-significant shift in its alignments which represent stretching vibration and the angular deformation of the -CH 2 groups in the protein residues moieties [ 11 , 15 ]. The calculated intensities values for chitosan’s -CH 2 groups absorbance subjected to increasing deacetylation periods were 0.09034%; 0.07202%; 0.06696% and 0.03678% for the products deacetylated for 22 hrs; 30 hrs; 36 hrs and 40 hrs, respectively. The bands assigned near 1585 cm − 1 for the extracted chitosan and at 1591 cm − 1 for the commercial one can be referred to as the amide-II groups and describe the -N-H bending modes. Through the N-deacetylation of chitin, the band assigned close to 1655 cm − 1 is gradually diminish, while that at the range of 1584–1591 cm − 1 increased, demonstrating the occurrence of -NH 2 groups [ 14 ]. The methyl group in -NHCOCH 3 (amide bond) is estimated to be located close to 1375 cm − 1 in the extracted and commercial chitosan. On the other hand, oxygen stretching vibration in the glycosidic bond and the antisymmetric stretching of the C–O–C bridge are assumed to be assigned near 1150 cm − 1 [ 16 , 17 ]. Moreover, it can be claimed that the bands related to the inorganic carbonates are similar to that of shrimp shells, assigned at 1421 cm − 1 and 892 cm − 1 with the probability of shift of those peaks based on the acid utilized in the extraction of the chitosan, as previously stated [ 18 ]. Those two vibration peaks suggest the existence of a carbonate group (CO 3 2− ), which can be partially due to the occurrence of carbon dioxide gas which is sorbed throughout the extraction procedure [ 19 ]. Additionally, the peaks at 892 cm − 1 can be attributed to pyranose ring stretching vibration [ 18 ]. Based on data in Figure (1-CHC) the most peaks of interest for the commercial chitosan were: 3356 cm − 1 ; 3291 cm − 1 ; 2855 cm − 1 ; 1649 cm − 1 ; 1591 cm − 1 ; 1421 cm − 1 ; 1373 cm − 1 ; 1150 cm − 1 ; 1061 cm − 1 ; 990cm − 1 ; 892 cm − 1 and 438 cm − 1 . In brief, the figures for the peaks assignment for deacetylated chitosan, under consideration, are in great agreement with the peaks of the commercial chitosan and that published in the literature [ 11 , 20 – 22 ]. To summarize the most peaks of interest and characterizing the extracted chitosan, in general, are near the range 3360 − 3290; 2855–2879; 1584–1592; 1320–1449 besides 1420; 1348; 1150; 1078; 1035; and 417 cm − 1 . Close figures for peaks assignments were published by Singh et.al [ 19 ]. Degree of Deacetylation (DD) [ 2 ] As stated before, the degree of deacetylation is one of the main crucial factors that influence the quality of chitosan. The greater is the deacetylation degree, the greater is the purity of the chitosan. The degree of deacetylation is usually described as a vital parameter for verifying the thermal stability, the biological efficiency, biomedical applications, polymeric as well as the physical and chemical properties of chitosan [ 23 – 27 ]. Additionally, the DD is an important factor demonstrating the deacetylation process efficiency for chitin precursor. The whole experimental conditions are the principal determinate factors affecting not only the main characters of the produced chitosan but also the chitin’s deacetylation outputs. It was published that the concentration of sodium hydroxide [NaOH] is the main factor in the deacetylation stage, where the deacetylation degree escalates by rising NaOH concentration. Moreover, the escalation in reaction periods results in a rise in the DD%, Table 1. On the other hand, the rising of these two factors i.e. NaOH concentration and the deacetylation time, leads to a reduction in the intrinsic viscosity and molecular weight of the yielded chitosan [ 28 ]. Table 1 presents the molecular weight of the obtained chitosans which is smaller than 41300 for commercial ones comparable to 15280, 14957, 13349, and 14421 for chitosans after chitin deacetylation for 22hrs, 30hrs, 36hrs, and 40hrs, respectively. Evaluation the Degree of Deacetylation (DD) Determination of the deacetylation degree for the different variables of the extracted chitosan, in this study, is based on the ratio of the intensities of the absorption bands near 1320 cm − 1 and that near 1420 cm − 1 for each product. In the extracted chitosan spectra, the peak near 1420 cm − 1 for stretching vibration of -CH 2 groups in -CH 2 OH at C-6 is assumed to be one of two standard peaks, while the peak close to1320 cm − 1 is the second and corresponding to the characteristic band of amide groups (-OH, -NH 2 , -CO) [ 20 ]. First, the degree of acetylation magnitudes of chitin, (DA %), can be computed, as presented in Eq. (1): [ 17 , 20 , and 29 ] 𝐷𝐴 % = 31.92 *(𝐴1320/ 𝐴1420) − 12.20 …… (1) Secondly, the degree of deacetylation percentage, (DD %), is calculated according to the Eq. (2) [ 30 ]. 𝐷𝐷 % = 100 − 𝐷𝐴 % …. (2) The acetylation DA% and deacetylation DD% data reached for the different acquired chitosan besides that for the commercial one are presented in Table (1) Table (1) It is assumed that the ratio relets the intensities of two bands near 1320 / 1420 presents a minor experimental error for evaluating the chitin deacetylation, despite of the method and the nature of the matter [ 2 , 31 ]. The degrees of deacetylation, DD%, escalate as the decline in the number of the acetyl groups and attribute to the protonation of the -NH 2 groups on the carbon 2 (C2) position of the replicating D-glucosamine units. This proposing distinguished quality chitosan product [ 20 ]. According to Joseph et.al and based on the data obtained for deacetylation, the extracted chitosan under consideration can be classified as a product with high deacetylation degree (HDD) (70% – 99%) [ 32 ]. It is reported that the deacetylation degree of the commercial chitosan ranges, mainly, from 74–80% [ 33 ]. It is worth to state that the purchased one and used for comparison in this study has DD % near 76%. Compared to the figures obtained in the present study, this value is comparable to the extracted chitosan which subjected to increasing deacetylation periods [Table 1]. Scanning Electron Microscopy (SEM) The microstructure of the shrimp shells, under consideration, as precursor for chitin and chitosan as well as the impact of each processing step on the morphology of every product were examined by SEM. Figure (2-I) presents the topography of shrimp shell waste, under consideration, which indicates main four layers for the shell, namely, the epicuticle [A], the exocuticle [B], the endocuticle [C], and inner membrane [D]. The three former layers are observable as definite layers in the micrograph while the inner membrane is very thin, discontinuous, and hard to detect. The shell architecture looks to be fibrous. The thickness of the three layers is arranged as exocuticle > epicuticle > endocuticle. The same arrangement was reported by Xu et.al [ 34 ]. Figure (2) Shrimp shells show a heterogeneous morphology distinguished by a compacted assembly with well-distinct chips-like shapes that have white spots. Additionally, the shell seems to possess a tough overlay with very rare pores which is attributed to the existence of protein and mineral components that appeared as white spots. Figures (2-II) [ 35 , 36 ]. The internal structure of chitin and chitosan was examined, also, by scanning electron microscope. Figures (2, III-XVIII) presents the SEM photos of chitin, commercial and extracted chitosan with several magnifications and at various zones. The obtained chitin past demineralization and deproteinization processing of the shrimp shells possessed irregular smooth microstructures. Moreover, the micrograph presents blocky fiber arrays besides the uneven distinct horizontal fiber structures. Figures (2-III). However, the topography of chitin and /or chitosan is dependent upon the type and the method of processing of the shells [ 37 – 40 ]. Chitin is displaying, also, a compactly flattened morphology, containing round pores collection with thick walls surrounding the pores and the remains of the spouts within (Fig. 2-IV). The white cake-like locations in the shells are assumed to be substituted by the rounded pores as a result of the deletion of protein and calcium carbonates [CaCO 3 ] crystals after the demineralization and deproteinization steps [ 39 ]. Comparable remark was stated by Yen et al. (2009), [ 41 ], Arbia et al. [ 42 ], and Muzzarelli et al. [ 43 ]. In this examined area of chitin, the pores sizes are ranged from 4.642 µm to 13.14 µm (Fig. 2-V). An outline SEM micrograph for the commercial chitosan is presented in Figure (2- VI) and pairs of detailed photos are depicted in Figure (2 VII-IX). The former image, with magnification 250x, demonstrates discontinuous, uneven blocky fiber structures, crumbly flakes, and even soft areas. At 1000x magnification for a selected slice of commercial chitosan, fibril arrangements can be differentiated, in addition to rough, disordered, disorganized, some cracks, and hardly detected very small pores with distorted topography Figure (2-VII). Moving to another area: lump and little white gatherings similar to that manifested in shrimp shell microstructure were detected in Figure (2-VIII). Also, at 1000x magnification, at an additional area of the commercial chitosan, a more or less even flattened surface with micro-pores can be manifested. Figures (2, IX). Similar results were reported [ 16 , 44 ]. The architectures of the extracted chitosan were examined, also, by SEM and the micrographs with different magnifications, different areas, and those subjected to escalating deacetylation periods are presented in Fig. 2 [X- XVIII]. The microstructures at different parts for chitosan generated from the deacetylation of chitin for 22 hours are presented in Fig. 2 (X, XI) with magnifications 800x & 2500x, respectively. At 800x magnification more or less even flattened surface besides regular rough smooth microstructure with very rare micro-pores can be manifested. Figures (2-X). On the other hand, at 3000x and at other spots: folded surface, irregular pattern, with some longitudinal spaces in-between, little threads, and no obvious pores can be distinguished. Figures (2-XI). For chitosan deacetylated for 30 hrs, the examination of the outcome at magnification 250x display asymmetric arrangements with irregular flacks. The surfaces are of various particle sizes and various lumpy, rough fissures, and irregular pattern, with some void spaces, little tiny threads, and no distinct pores can be differentiated Figure (2-XII). As the deacetylation degree after 30 hours recorded only ≈ 78.23%, Table 2, the micrograph, at 1000x magnification in Figure (2-XIII) for the extract chitosan showed traces of non-deacetylated chitin. Examining other area, at 1500x magnification, showed uniformity brick like shape topography with trace of carbonate residues and micropores which can be hardly viewed [ 16 , 45 ] (Fig. 2- XIV). The microstructures at different parts of chitosan generated from the deacetylation of chitin for 40 hours are presented in Fig. 2 (XV-XVIII) with magnifications 250x, 1000x & 2000x, respectively. An overview at magnification 250x, for the extracted chitosan and deacetylated for 40hrs, the sample shows predominant smooth and plane region. A smooth polymer with chips-like plates and distinguished pores can be viewed also within this area (Fig. 2-XV). Examination at another spot and at magnification 1000x indicates folded zone with unevenness structure, tough, irregular arrays, clear fissures and no definite pores can be distinguished. The micrograph discloses, also, a rough, disordered, disorganized and crumbled microstructure surface Figure (2-XVI). Applying a higher magnification 2000x, reveals a soft and homogenous separated area demonstrating a plywood pattern structure. Traces of the white lumps as that of the shrimp shell can also be detected, in this area of examination. Moreover, pairs of micro-pores can be detected in this area (Fig. 2-XVII). The lack of homogeneity in the chitosan surface with a flattens area and roughness of another can be attributed to incomplete extraction of the chitosan from shrimp shells (Table 2). The micrograph of (Fig. 2-XVIII) at 2000x magnification in another part presents, also, that chitosan has an uneven and wavy identities which were affected by the deacetylation treatment of chitin. This can confirm the impact of deacetylation time on the properties and morphology of the chitosan output [ 46 ]. Based on the SEM examination the following remarks can be summarized: - Generally, it can be confirmed that the extraction technique of chitosan displays variations in the shape and morphology of the final product. - There is no entire elimination for all minerals, protein, and impurities from the precursor shrimp shells. - The lack of homogeneity in chitosan’s surface with smooth segment and rough area is the indications of part split-up and signify the incomplete extraction process. - The impact of the used chemical concentration and processing period applied influence the architectures microstructure of the final product. The spectra of Energy dispersive analyses of X-ray spectroscopy (EDX) for shrimp shell, extracted chitin, commercial chitosan, and deacetylated one for 30 hours were presented in Figure (3 a-d and Table 2). The elemental constitution of the four stuffs corroborated that the principal peaks in the four spectra are for carbon (C) and oxygen (O). The intensity of the carbon peaks was maximum for chitin, (Fig. 3b), followed by commercial and extracted chitosan, (c & d), while, the lowest peak intensity was for the shrimp shell (Fig. 3a). This can be attributed to the concentration of carbon contents after demineralization and deproteinization followed by dissolution due to deacetylation processes. It is clear from Figure (3 a-d) and Table 3 that the mass of calcium (Ca) % is found in the shrimp shell near 10% and at concentrations less than 1% in both chitin and two chitosans. Concerning the presence of traces of Ca in chitin and chitosan outputs, (Fig. 3, b, c &d), Li et. al., [ 40 ] and Guan et. al., [ 47 ], proposed that, the pureness of the extracted chitin and chitosan is based on its origin, demineralization and deproteinization applied techniques, chemicals used [ 20 ] and processing period [ 40 ]. Figure (3) Table (2) This result proves the incapacity of diluted acid to remove all minerals from the shrimp shells, contrary to concentrated acids can leave just a few minerals traces. It is clear from Table 2, also, that there are insignificant variations in the composition of the commercial chitosan compared to the extracted chitosan under consideration. It worth to state that these very minute differences can be referred to shrimp origin, demineralization and deproteinization applied techniques, chemicals used processing period and even the shelf shipping conditions and period [ 40 , 47 ] . According to the United States Environmental Protection Agency (U.S. EPA), and the International Agency for Research on Cancer (IARC): arsenic, cadmium, chromium, lead, and mercury, due to their high degree of toxicity, these five elements classified among the main concern metals that are of great public health significance. They are all systemic toxicants that are known to provoke multiple organ damage, even at lower levels of exposure [ 48 ]. Consequently, and based on EDX analysis, this confirms that the extracted chitosan under consideration, in connotation, would be a safe and non-toxic product when used in medical, pharmaceutical, biological, and food stuff industries. Ultraviolet-Visible Spectroscopic Analyses The Ultraviolet-Visible (UV–Vis) spectra for extracted chitosan acquired from chitin deacetylated for 22 hrs, 30 hrs, 36 hrs, 40 hrs, and commercial chitosan, are presented in Figure (4). The UV–Vis spectra for each stuff display distinguishing absorption bands. Table (3) depicts the absorption maximum for the extracted chitosan generated from deacetylation for 22 hrs (CHI); 30 hrs (CHII); 36 hrs (CHIII), 40 hrs (CHIV), and commercial chitosan (CHC). Figure (4) The absorption spectra of UV–Vis for the five stuffs are comparable and allocated peaks λ at 238, 245, 248, 242, and 242 nm for extracted chitosan acquired from deacetylation for 22 hrs, 30 hrs, for 36 hrs and 40 hrs and for CHC respectively. Even they differ in their intensities, it should be stated that the extracted chitosan generated after chitin deacetylation for 40 hrs has a third peak at λ 346 nm. It was reported that the peak between 300–370 nm is chrematistic for chitosan [ 49 ]. Little bite shift can happen to the low limit at λ 290 nm. On the same trend, the peak at λ 300–360 nm contributes to the absorption linked to the direct electronic π-d orbitals and is entitled as the Soret band [ 50 ]. The sharp peaks for chitosan in the UV -Vis can verify their promise usages in waste water handling, nanoparticle invention and others [ 51 ]. Table (3) Thermal Characterizations The Thermogravimetric analysis (TGA) curves, the mass changes TG in % versus sample temperature, °C, are applied to present the changes in material composition and its thermal stability. On parallel, DTG curves apply to ascertain the number of thermal consequences to which the material has been exposed, since each DTG peak, at a given temperature provides the rate of mass loss (mg/min) through its temperature range, ( Ton, Tmax., Toff ), where Ton , is the temperature of onset mass loss; Toff is the temperature of offset mass loss and Tmax is the temperature of the maximum mass loss rate within that peak. Thermogravimetric analyses (TG & DTG) were achieved systematically for commercial chitosan (CHC), for extracted chitosan intended from increasing deacetylation periods for: 22 hrs (CHI); 30 hrs (CHII); 36 hrs (CHIII), and 40 hrs (CHIV) under the same analyses conditions. The thermal analyses for the commercial chitosan were performed for the sake of comparison. The data acquired are presented in Figure (5) and Table (4). It is claim that the chitosan polymer, in general, displayed four significant mass loss steps attributed to: water moisture loss, degradation of the organic moiety, including the protein remained in chitosan past the all-extraction steps, the decarboxylation of calcium carbonate, degradation of the inorganic matters and/or recrystallization of any amorphous inorganic substances. Similar trend was reported for chitin [ 6 , 52 ]. The TG curve for commercial chitosan demonstrates two steps of the polymer degradation. The first step began from 44.66°C up to 158.91°C with mass loss 6.08%. The corresponding DTG peak exhibits onset at 48.10°C, the temperature of the maximum mass loss rate within that peak at 87.24°C, and offset at 131.89°C with mass loss at a maximum of 7.09%. This mass loss is attributed to the water physically adsorbed inner and at the surface of CHF. The second step with a high mass loss of 49.97% started at 146.13°C and ended at 605.61°C. The parallel DTG curve displays onset at 278.83°C and offset at 323.87°C with swift mass loss of 33.17% at Tmax 305.26°C signifying the decomposition of the polysaccharide and protein moieties [ 6 ] Figure (5), Table (4). The chitosan CHI, CHIII, and CHIV are disclosed in the same manner as commercial ones, and undergo the two steps of mass loss. On the other hand, the chitosan CHII showed three steps of mass loss. The additional third step exhibits onset at 436.29°C and offset at 496.74°C with a mass loss of 2.196% at Tmax 476.32°C. This step can be attributed to the thermal dehydroxylation of calcium hydroxide [Ca (OH) 2 ] formed by increasing the deacetylation time, and took place in the region between 400°C and 600°C, followed by the decarboxylation of the formed carbonated phases and calcite up to 600°C according to Eq. (2) & Eq. (3), respectively [ 53 , 54 ]. Based on thermal analyses data, it can be deduced that a process of chitosan extraction has an impact on their thermal stability. It is clear from table (4) that the chitosan CHIV is most thermally stable compare to the other ones and even to the commercial chitosan. The chitosan II loses its mass gradually, past three degradations showing lowest mass loss i.e. 23.12%. Similar trends were previously published [ 55 – 57 ]. Parallel to the thermal analysis (DTA&DTG), the differential scanning calorimetry (DSC) curves for the different extracted chitosan were performed under Nitrogen atmosphere [Figure (5)]. Two decomposition stages for the all-chitosan preparations were disclosed which can be briefed as follows: the first one at ~ 80°C, compared to the commercial CHC at ~ 86°C and can be attributed to an endothermic reaction comprises the release of moisture surface water and hydrogen-bonded water. The second is a strongly exothermic peak that disclosed between 304°C – 313°C compared to 309°C for chitosan CHC. This degradation second step is attributed to the degradation of the rest cross-linked chitosan skeleton [ 58 ]. Hence, it can be noted that the thermal decomposition of the chitosan polymers, under consideration, happened in two marked steps. Based on the data acquired for the TGA, TGD, and DSC analyses, it can claim that the extracted chitosan from shrimp is characterized by acceptable thermal stability and can, practically, represent a valuable and cost-effective natural biosorbent for some hazardous and radioactive waste streams, in addition, to the other numerous agriculture and medical applications. The thermal destruction progression of chitosan leans to be quiet beyond 356.74°C. Though, this was a minor descending inclination near 600°C, and can be attributed to the residual carbon content [ 59 ], and comprises 13.01%, 13.22%, 10.07% and 9.38% for CHI, CHII, HIII and CHIV, respectively and comparable to commercial one (CHC), Figure (5). Hence, it can be noted that the thermal decomposition of the chitosan polymers, under consideration, happened in two marked steps. Based on the data acquired for the TGA, TGD, and DSC analyses it can be claimed that the extracted chitosan from shrimp shell is characterized by an acceptable thermal stability and can, practically, represent a valuable and cost-effective natural biosorbent for some hazardous and radioactive waste streams, in addition, to the other numerous agriculture, industrial and medical applications. According to the data obtained, based on thermal analyses, the following conclusions can be summarized: - The method of chitosan extraction has an impact on their thermal stability. -The water moisture loss happened in between ~ 44°C up to ~ 158°C comparable to that of commercial one Table (4). - The mass loss percentages due to water moisture depletion are in range from 5.61% − 8.77% with mean value 7.31% which is not far from the commercial chitosan (7.09%). - The mass losses next to the first step, are largely, assigned to a complicated processes involving: dehydration of the polysaccharide rings, depolymerization and decomposition of the deacetylated moieties of chitosan, besides, to dehydroxylation and destruction processes. - As of the extensive magnitude of inter- and intramolecular hydrogen bonding in chitosan; accordingly, it needs additional energy to fracture [ 60 ]. -The acceptable thermal stability of the developed chitosan, under consideration recommend it as effective biosorbent for treatment of some hazardous and radioactive waste streams, even, at temperature near 100°C. -The final mass loss for the chitosan is above 600 ° C which assumed to be due to the decomposition of the traces of CaCO 3 decomposed to CaO and CO 2 [ 61 ]. -The adequate thermal stability of chitosan under consideration can be attributed to the intramolecular and intermolecular hydrogen bonds [ 62 ]. Table (4) Figure (5) Conclusion Based on the experimental data reached, the following conclusions can be reported: The conventional chemical method applied is a reliable, straightforward, and cost-effective technique for extracting chitosan from shrimp shell waste due to the cheap chemical used, non-sophisticate, and consistent processes. Practically, increasing the deacetylation time of chitin significantly influences the Degree of Deacetylation (DD) of chitosan and, consequently, affects its spectroscopic characteristics. Moreover, the spectroscopic tools used are effective for indicating the impact of various deacetylation times on the configuration of the extracted chitosan. Additionally, the results reached confirm that the extracted chitosan, under consideration, is pure, ultrafine, and non-toxic, with an acceptable degree of deacetylation (DD) of nearly 80%. The extracted chitosan exhibits acceptable heat resistance, showing no thermal degradation until it reaches 300°C. This resistance is comparable to that of commercial chitosan. The configuration of chitosan closely resembles that of cellulose, with the distinction that the hydroxyl group at the C-2 position in cellulose is replaced by an amino group in chitosan. This -NH 2 group enables chitosan to effectively scavenge pollutants, such as heavy metals and radionuclides, from waste solutions. As waste recycling becomes of global interest, shrimp shell wastes can be utilized more effectively by extracting chitosan, which can then be applied in a wide variety of everyday applications. From an environmental point of view, stimulating marine biomass can yield significant economic and environmental benefits for industries, including the fishery sector. Utilizing shrimp waste as a source of chitosan extraction on an industrial scale would help address the accumulation of waste generated by processing plants, presenting a challenge for both the industry and community health. Future projects are planned to explore the combination of the extracted chitosan with certain cellulose derivatives, either as a backbone or a cross-linking agent. These combinations are expected to produce various hydrogel products with promising economic value that can be applied in many areas of daily life. It is recommended, also, that more studies can focus on investigating the antimicrobial and antioxidant properties of chitosan extracted from Egyptian shrimp shell wastes. Declarations Compliance with ethical standards conflict of interest On behalf of all authors, the corresponding author affirms that there is no conflict of interest to publish this work. Competing interests : The authors declare no competing interests. Consent for publication : All the authors listed have approved the manuscript and consented for publication. Ethics approval and consent to participate : The authors state that the present work is in compliance with ethical standards. All the authors listed have approved the manuscript and consented to participate. Data availability : Data sharing not applicable to this article as all datasets were generated or analyzed during the current study. Funding Open Access This article is licensed under (STDF). Egyptian institutions are participating in the transformative agreement between Springer Nature and Science, Technology & Innovation Funding Authority (STDF) in cooperation with Egyptian Knowledge Bank (EKB). This agreement covers all the public, private and national universities, as well as the research centers related to the Ministry of Higher Education and Scientific Research and all other governmental ministries in Egypt. Author contributions M.E.T designed the experiment, organized the experimental process, participated in the experiments and wrote the paper with S.B.E. S.N.G, participated in the experiments. All authors have read and approved the final manuscript. 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Supplementary Files graphicalabstract.tif Graphical abstract: Preparation of chitosan Table13.docx Cite Share Download PDF Status: Published Journal Publication published 16 Jul, 2025 Read the published version in BMC Chemistry → Version 1 posted Editorial decision: Revision requested 13 May, 2025 Editor assigned by journal 13 May, 2025 Reviews received at journal 27 Apr, 2025 Reviewers agreed at journal 27 Apr, 2025 Reviewers agreed at journal 09 Apr, 2025 Reviewers invited by journal 31 Mar, 2025 Submission checks completed at journal 31 Mar, 2025 First submitted to journal 28 Mar, 2025 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. 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Marzouk","email":"","orcid":"","institution":"Ain Shams University","correspondingAuthor":false,"prefix":"","firstName":"M.","middleName":"I.","lastName":"Marzouk","suffix":""},{"id":436266387,"identity":"589c4b61-39a2-4a74-8a40-7530ab5a04d9","order_by":2,"name":"Magda Tawfik","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIiWNgGAWjYJACCSDm4QOxPjAwJBCvhY2BmYFxBilaGEBamHmI0aLbfvzijR8V22TY2PsPfrZts8vjZ29g/PAxB7cWszM5xZY9Z27zsPEcZpbObUsuluw5wCw5cxseLQdy0iR424BaJJIZgFqYEzfcSGBj5sWn5fybNMm//4Ba5B8z/7ZsqydCy430Y9K8DSBbmNmkGdsOE6PlDbO1zDGQX5LNLHvOHU+c2XOwGb9fzqc/vPmm5rY9P/vBxzd+lFUn9rM3H/zwEY8WYCQaINiMbGCyAZ96IGB/gMT5Q0DxKBgFo2AUjEgAABU8UhKeh3BcAAAAAElFTkSuQmCC","orcid":"","institution":"National Research Centre","correspondingAuthor":true,"prefix":"","firstName":"Magda","middleName":"","lastName":"Tawfik","suffix":""},{"id":436266388,"identity":"fab0db74-5173-4166-9a56-364872258192","order_by":3,"name":"Samir Eskander","email":"","orcid":"","institution":"Egyptian Atomic Energy Authority","correspondingAuthor":false,"prefix":"","firstName":"Samir","middleName":"","lastName":"Eskander","suffix":""}],"badges":[],"createdAt":"2024-12-27 19:23:06","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-5723322/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-5723322/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s13065-025-01558-3","type":"published","date":"2025-07-16T15:57:01+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":79670052,"identity":"c6c8ed8f-6301-4959-8d9a-481af0026cf0","added_by":"auto","created_at":"2025-04-01 10:57:59","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1009550,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR-ATR spectra of commercial and various extracted chitosan acquired from chitin subsequent to increasing deacetylation periods time\u003c/p\u003e","description":"","filename":"Fig1.png","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/e3a5bb41e94349192c1e7c5b.png"},{"id":79671143,"identity":"3800a56a-88ce-42b3-8c2c-855144a24ec1","added_by":"auto","created_at":"2025-04-01 11:13:59","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":243525,"visible":true,"origin":"","legend":"\u003cp\u003eScanning Electron Microscopy examinations with magnification 250x, 500x, 800x, 1000x, 1500x, 2000x and 3000x for shrimp shell [I \u0026amp; II], chitin [III-V], commercial chitosan [VI-IX], extracted chitosan deacetylated for 22 hours [X-XI], extracted chitosan deacetylated for 30 hours [XII-XIV] and extracted chitosan deacetylated for 40 hours [XV-XVIII]\u003c/p\u003e","description":"","filename":"Fig2.png","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/54407b08cff34cb1add08737.png"},{"id":79668969,"identity":"3858d794-08c8-48af-bf57-0c246a239f4a","added_by":"auto","created_at":"2025-04-01 10:49:59","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":297932,"visible":true,"origin":"","legend":"\u003cp\u003eEDX spectra analyses for (a): shrimp shell, (b): chitin: EDX spectra analyses for (c): commercial chitosan (d): extracted chitosan after chitin deacetylation for 30 hours\u003c/p\u003e","description":"","filename":"Fig3.png","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/22f4d05f800a23b5480ab7d1.png"},{"id":79670053,"identity":"f3d63380-8db1-4845-9e87-d3d3e375854d","added_by":"auto","created_at":"2025-04-01 10:57:59","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":697874,"visible":true,"origin":"","legend":"\u003cp\u003eUV–Vis spectra for the deacetylated chitosan for 22 hrs (CHI); 30 hrs (CHII); 36 hrs (CHIII), (CHIV) and for commercial chitosan (CHC)\u003c/p\u003e","description":"","filename":"Fig4.png","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/a3ee92bccda81163a6ce4676.png"},{"id":79671145,"identity":"2edfd763-a49f-4e24-8e5c-2240fd01a6b2","added_by":"auto","created_at":"2025-04-01 11:13:59","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":269305,"visible":true,"origin":"","legend":"\u003cp\u003eTG [A], DTG [B] \u0026amp; DSC [C] thermograms of commercial chitosan and extracted ones generated from chitin deacetylation for escalated periods\u003c/p\u003e","description":"","filename":"Fig5.png","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/2898d43b7a5cc6891b891942.png"},{"id":87219340,"identity":"22bac0a9-ca00-49bd-ba4e-8f356cacd02c","added_by":"auto","created_at":"2025-07-21 16:03:53","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4127867,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/a3fbd92f-b464-42a1-bdf9-4bed8f53ccad.pdf"},{"id":79668976,"identity":"5796ef07-33ba-4777-b546-e01decbd73f1","added_by":"auto","created_at":"2025-04-01 10:49:59","extension":"tif","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":2902057,"visible":true,"origin":"","legend":"\u003cp\u003eGraphical abstract: Preparation of chitosan\u003c/p\u003e","description":"","filename":"graphicalabstract.tif","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/e862897a095bab87470c0252.tif"},{"id":79668971,"identity":"e65eacdb-b3b4-4a4a-8958-0eb0c4b6ef4e","added_by":"auto","created_at":"2025-04-01 10:49:59","extension":"docx","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":27242,"visible":true,"origin":"","legend":"","description":"","filename":"Table13.docx","url":"https://assets-eu.researchsquare.com/files/rs-5723322/v1/de6b62112e8a3ec1b0545894.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Spectroscopic Approaches for Structural Analysis of Extracted Chitosan Generated from Chitin Deacetylated for Escalated Periods","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe name chitosan designates a chain of deacetylated chitin macromolecules with diverse molecular weight, viscosity, and degree of deacetylation, (DD) (40\u0026ndash;99%). Chitosan is a linear polyamine with a number of amino groups that are accessible for chemical reactions with acids or other active groups [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. It is a cationic amino polysaccharide and it has extensive applications in many fields: in medicine, biomedical and pharmaceutical industries e.g. fibers, membranes, and artificial organs; in biology; in agriculture; in the environment; in the field of cosmetic production alike body creams, lotions, additives for the hair; in addition to some foodstuff manufactures e.g. binder, gelling agent, thickener; antimicrobial agents and antioxidants fabrication are among others [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Chitosan has great attention among researchers, due to its efficient scavenger capability for heavy metals [\u003cspan additionalcitationids=\"CR5 CR6\" citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Chitosan beads can be applied, also, to sorb radionuclides e.g. radiocesium, radiocobalt \u0026hellip;etc., from radioactive aqueous solution streams [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eDifferent practices have been applied to extract chitin and consequently chitosan, but the furthermost widespread is the chemical processing route [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eMany analysing tools are used to characterize the chitosan products, among all those methods: Fourier Transformed Infra-Red, Thermal analyses, and Scanning Electron Microscope prove to be a very beneficial tool since it was applied to reveal the amount and the nature of chemical fractions generated from various composite materials in addition to DD evaluation [\u003cspan additionalcitationids=\"CR12\" citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this study all-chitosan products extracted from shrimp shell wastes are subjected to characterization using UV-visible spectroscopy, Fourier Transformed Infra-Red (FTIR-ATR) examination, Thermogravimetry, Derivative thermogravimetry (TG/DTG), Differential scanning calorimetric analyses (DSC), Scanning Electron Microscope (SEM), and Energy-dispersive X-ray spectroscopy (EDX) analysis. Those tools were applied to evaluate the impact of increasing deacetylation periods on the physico-chemical properties of the obtained chitosan and to compare it to the commercial chitosan purchased from Sigma Reagent Co.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\n \u003ch2\u003eMaterials\u003c/h2\u003e\n \u003cp\u003eFresh samples of shrimp shells were obtained from the wastes of processing discards and collected from a local shrimp market in Egypt. The shrimp shell wastes (SSWs) under consideration, were selected, packed in plastic bags, and stored at (-10\u0026deg;C) before and during transportation to the laboratory. The SSWs were washed with water and soap several times, boiled with water and soap for 10 min, rewashed, and then dried in an oven at 90\u0026deg;C. Finally, the clean dried shells were ground to the predetermined smallest mesh sizes.\u003c/p\u003e\n \u003cp\u003eCommercial chitosan with 76% deacetylation degree was purchased from Sigma Reagent Co., Ltd. It was used as a reference for comparison with the extracted one. All other used chemicals in this study were of analytical grade and applied without any further purification.\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eMethods\u003c/h3\u003e\n\u003cdiv id=\"Sec5\" class=\"Section2\"\u003e\n \u003ch2\u003eExtraction of chitosan\u003c/h2\u003e\n \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e\n \u003ch2\u003eDemineralization step (1)\u003c/h2\u003e\n \u003cp\u003eThe demineralization of ground shrimp shells was carried out at room temperature (25\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u0026deg;C) using 1M hydrochloric acid until the production of carbon dioxide (CO\u003csub\u003e2\u003c/sub\u003e) gas was completely stopped. The demineralized ground shells were filtered under suction through a Buchner funnel with coarse porosity filter paper Whatman No. 40, and the residue was washed with distilled water several times till it reached neutral pH (6.5\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5). Finally, the solid material was dried in a drying oven at 90 \u0026ordm;C for constant mass. The chemical reaction for this step can be illustrated as follows: the minerals in the shells (mainly calcium carbonate) are decomposed into calcium chloride along with the discharge of carbon dioxide, by hydrochloric acid at room temperature.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003e2HCl\u0026thinsp;+\u0026thinsp;CaCO \u0026rarr; CaCl\u0026thinsp;+\u0026thinsp;HO\u0026thinsp;+\u0026thinsp;CO \u0026uarr;.........(1)\u003c/h3\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eDeproteinization step (2)\u003c/h2\u003e\n \u003cp\u003eDeproteinization of the demineralized SSWs was carried out using 1.0 M sodium hydroxide solution (NaOH) (1:10 mass/v ratio of demineralized SSWs to NaOH) at (100\u0026thinsp;\u0026plusmn;\u0026thinsp;5) \u0026deg;C for one hour. This step was repeated several times. The absence of protein was indicated by the absence of a pale pink color in the medium. The product was rinsed with distilled water up to neutral pH. At this stage, perfectly white chitin is isolated. Any traces of pigment colors can be removed by applying a mild oxidizing agent for chitin (KMnO\u003csub\u003e4\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;oxalic acid\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eSO\u003csub\u003e4\u003c/sub\u003e), washed with distilled water, and then dried in an oven at 90\u0026deg;C (9).\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eDeacetylation of chitin step (3)\u003c/h3\u003e\n\u003cp\u003eThe deacetylation of chitin can be highly facilitated by steeping it for 48 hours in concentrated sodium hydroxide solution, (40% by mass) at room temperature (25\u0026thinsp;\u0026plusmn;\u0026thinsp;5) \u0026deg;C before heating. Then, the container used for deacetylation was subjected to reflux at (100\u0026thinsp;\u0026plusmn;\u0026thinsp;5) \u0026deg;C, at normal pressure, and for up to 40 hours; the reaction was accompanied by drastic degradation of the chitin-producing chitosan. The obtained chitosan was washed with distilled water to a neutral pH and oven-dried at 90\u0026deg;C for constant mass [\u003cspan class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e\n\u003ch3\u003eEvaluation and Analyses\u003c/h3\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003eFourier-Transform Infrared Spectroscopy (FTIR-ATR)\u003c/h2\u003e\n \u003cp\u003eThe most interested functional groups of the prepared samples were determined by Fourier-Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR), Bruker Vertex 80V with resolution 4cm\u003csup\u003e-1\u003c/sup\u003e in the range of 4000\u0026ndash;400cm\u003csup\u003e-1\u003c/sup\u003e. The sample was examined directly in a powder form without preparation.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec12\" class=\"Section2\"\u003e\n \u003ch2\u003eScanning Electron Microscope and Energy-dispersive X-ray spectroscopy (SEM-EDX)\u003c/h2\u003e\n \u003cp\u003eThe surface morphology of shrimp shell, chitin, commercial chitosan, and extracted chitosan acquired from chitin deacetylation for increasing periods were investigated by applying the surfaces of small pieces to field-emission scanning electron microscope (FE-SEM, Quanta FEG-250) at 20Kv after covering with a thin layer of gold. The samples were subjected to the dry tiny pieces of the various samples to gold plating in S150 a Sputter Coater Edwards (England).\u003c/p\u003e\n \u003cp\u003ePredetermined samples were subjected to analysis by Energy-dispersive X-ray spectroscopy (EDAX) AMETEK Materials Analysis Division.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003eUltraviolet / Visible spectroscopy\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eUV/visible absorption spectra (200 to 900 nm) were recorded by Cary-100 UV-2450 spectrophotometer using a slit width of 2 nm. A pair of quartz cuvettes with a path length of 1cm was employed for this purpose. Samples of commercial chitosan and extracted chitosan acquired from chitin deacetylation for increasing periods were dissolved in 0.1% acetic acid solution and absorbance spectra of the samples were measured at above selected wavelength ranges. Duplicate measurements were made for each sample and the average values were reported.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003eThermal analysis\u003c/h2\u003e\n \u003cp\u003eThermogravimetric (TGA) Differential Thermogravimetric (DTG) and Differential scanning calorimetric analyses (DSC) were performed using Setaram KECHNOLOGIES Themys one (France). Each analysis was performed in a platinum cell under a nitrogen atmosphere at a flow rate of 20 ml/min starting from room temperature up to 600 \u003csup\u003eo\u003c/sup\u003eC at a heating rate of 10 \u003csup\u003eo\u003c/sup\u003eC /min.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Results and Discussion","content":"\u003cp\u003eThe chitosan can successfully be prepared from the deacetylation of chitin which is extracted chemically from shrimp shells. The quality and physicochemical properties of prepared chitosan are varied widely with the quality of shrimp shell, chitin, and methods of preparation. The production of chitosan is based on the deacetylation reaction of chitin i.e. of hydrolysis of chitins\u0026rsquo; acetamide groups. This is associated, also, with the splitting of chitin\u0026rsquo;s acetyl group with the formation of an amino group. Additionally, the deacetylation reaction can be associated with a concurrent rupture of the polymer glycosidic bonds.\u003c/p\u003e\n\u003cdiv id=\"Sec16\" class=\"Section2\"\u003e\n \u003ch2\u003eFTIR -ATR Analysis\u003c/h2\u003e\n \u003cp\u003eInfrared spectroscopy is one of the highly interesting and extensively applied analytical practices, based on the vibrations of the atoms of a molecule, to study the chemical configuration of materials. Moreover, FT-IR analysis can be used to evaluate the degree of deacetylation of chitosan extracted from shrimp shell waste. In this study, FTIR-ATR analyses were performed systematically for commercial chitosan (CHC) for comparison, besides for the extracted chitosan acquired from chitin following increasing deacetylation periods i.e.: 22 hrs (CHI); 30 hrs (CHII); 36 hrs (CHIII), and 40 hrs (CHIV) under the same analyses\u0026rsquo; conditions, to evaluate the impact of escalation of deacetylation periods on DD % and their spectra. The results obtained are presented in Figure (1) and Table\u0026nbsp;(1).\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eFigure (1)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eIt is clear from Figure (1) that, a very wide absorption peak between 3362\u0026thinsp;\u0026minus;\u0026thinsp;3286 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e that signify stretching vibration of the hydroxyl group (-OH), an amine group (-NH\u003csub\u003e2\u003c/sub\u003e), and hydrogen bonding in the extracted chitosan (CHI-CHIV). Those are very comparable to the spectrum peak of commercial one, i.e., 3361\u0026thinsp;\u0026minus;\u0026thinsp;3283 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e (CHC). It is worth to notify that, not any of the presented spectra in Figure (1), even the commercial chitosan, showed any sharp peak close to 3500 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e, which corroborates that the hydroxyl groups in positions C2 and C6 of the chitosan are engaged in intra- and intermolecular hydrogen bonds [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe band assigned close to 2879 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be attributed to -C-H stretching vibration, even when there is a shift of this peak according to the acid utilized in the extraction of the chitosan. The deproteinization step of chitosan can be prove by the decline in the -CH signal absorbance intensity and non-significant shift in its alignments which represent stretching vibration and the angular deformation of the -CH\u003csub\u003e2\u003c/sub\u003e groups in the protein residues moieties [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e]. The calculated intensities values for chitosan\u0026rsquo;s -CH\u003csub\u003e2\u003c/sub\u003e groups absorbance subjected to increasing deacetylation periods were 0.09034%; 0.07202%; 0.06696% and 0.03678% for the products deacetylated for 22 hrs; 30 hrs; 36 hrs and 40 hrs, respectively. The bands assigned near 1585 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the extracted chitosan and at 1591 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for the commercial one can be referred to as the amide-II groups and describe the -N-H bending modes.\u003c/p\u003e\n \u003cp\u003eThrough the N-deacetylation of chitin, the band assigned close to 1655 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is gradually diminish, while that at the range of 1584\u0026ndash;1591 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e increased, demonstrating the occurrence of -NH\u003csub\u003e2\u003c/sub\u003e groups [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe methyl group in -NHCOCH\u003csub\u003e3\u003c/sub\u003e (amide bond) is estimated to be located close to 1375 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e in the extracted and commercial chitosan. On the other hand, oxygen stretching vibration in the glycosidic bond and the antisymmetric stretching of the C\u0026ndash;O\u0026ndash;C bridge are assumed to be assigned near 1150 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eMoreover, it can be claimed that the bands related to the inorganic carbonates are similar to that of shrimp shells, assigned at 1421 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 892 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e with the probability of shift of those peaks based on the acid utilized in the extraction of the chitosan, as previously stated [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e]. Those two vibration peaks suggest the existence of a carbonate group (CO\u003csub\u003e3\u003c/sub\u003e\u003csup\u003e2\u0026minus;\u003c/sup\u003e), which can be partially due to the occurrence of carbon dioxide gas which is sorbed throughout the extraction procedure [\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eAdditionally, the peaks at 892 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e can be attributed to pyranose ring stretching vibration [\u003cspan class=\"CitationRef\"\u003e18\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eBased on data in Figure (1-CHC) the most peaks of interest for the commercial chitosan were: 3356 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 3291 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 2855 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 1649 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 1591 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 1421 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 1373 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 1150 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 1061 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 990cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e; 892 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and 438 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. In brief, the figures for the peaks assignment for deacetylated chitosan, under consideration, are in great agreement with the peaks of the commercial chitosan and that published in the literature [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e22\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eTo summarize the most peaks of interest and characterizing the extracted chitosan, in general, are near the range 3360\u0026thinsp;\u0026minus;\u0026thinsp;3290; 2855\u0026ndash;2879; 1584\u0026ndash;1592; 1320\u0026ndash;1449 besides 1420; 1348; 1150; 1078; 1035; and 417 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. Close figures for peaks assignments were published by Singh et.al [\u003cspan class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec17\" class=\"Section2\"\u003e\n \u003ch2\u003eDegree of Deacetylation (DD) [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e]\u003c/h2\u003e\n \u003cp\u003eAs stated before, the degree of deacetylation is one of the main crucial factors that influence the quality of chitosan. The greater is the deacetylation degree, the greater is the purity of the chitosan. The degree of deacetylation is usually described as a vital parameter for verifying the thermal stability, the biological efficiency, biomedical applications, polymeric as well as the physical and chemical properties of chitosan [\u003cspan class=\"CitationRef\"\u003e23\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e27\u003c/span\u003e]. Additionally, the DD is an important factor demonstrating the deacetylation process efficiency for chitin precursor. The whole experimental conditions are the principal determinate factors affecting not only the main characters of the produced chitosan but also the chitin\u0026rsquo;s deacetylation outputs. It was published that the concentration of sodium hydroxide [NaOH] is the main factor in the deacetylation stage, where the deacetylation degree escalates by rising NaOH concentration. Moreover, the escalation in reaction periods results in a rise in the DD%, Table\u0026nbsp;1. On the other hand, the rising of these two factors i.e. NaOH concentration and the deacetylation time, leads to a reduction in the intrinsic viscosity and molecular weight of the yielded chitosan [\u003cspan class=\"CitationRef\"\u003e28\u003c/span\u003e]. Table\u0026nbsp;1 presents the molecular weight of the obtained chitosans which is smaller than 41300 for commercial ones comparable to 15280, 14957, 13349, and 14421 for chitosans after chitin deacetylation for 22hrs, 30hrs, 36hrs, and 40hrs, respectively.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec18\" class=\"Section2\"\u003e\n \u003ch2\u003eEvaluation the Degree of Deacetylation (DD)\u003c/h2\u003e\n \u003cp\u003eDetermination of the deacetylation degree for the different variables of the extracted chitosan, in this study, is based on the ratio of the intensities of the absorption bands near 1320 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e and that near 1420 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for each product. In the extracted chitosan spectra, the peak near 1420 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e for stretching vibration of -CH\u003csub\u003e2\u003c/sub\u003e groups in -CH\u003csub\u003e2\u003c/sub\u003e OH at C-6 is assumed to be one of two standard peaks, while the peak close to1320 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e is the second and corresponding to the characteristic band of amide groups (-OH, -NH\u003csub\u003e2\u003c/sub\u003e, -CO) [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eFirst, the degree of acetylation magnitudes of chitin, (DA %), can be computed, as presented in Eq.\u0026nbsp;(1): [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e, and \u003cspan class=\"CitationRef\"\u003e29\u003c/span\u003e]\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec19\" class=\"Section2\"\u003e\n \u003ch2\u003e𝐷𝐴 % = 31.92 *(𝐴1320/ 𝐴1420)\u0026thinsp;\u0026minus;\u0026thinsp;12.20 \u0026hellip;\u0026hellip; (1)\u003c/h2\u003e\n \u003cp\u003eSecondly, the degree of deacetylation percentage, (DD %), is calculated according to the Eq.\u0026nbsp;(2) [\u003cspan class=\"CitationRef\"\u003e30\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec20\" class=\"Section2\"\u003e\n \u003ch2\u003e𝐷𝐷 % = 100 \u0026minus; 𝐷𝐴 % \u0026hellip;. (2)\u003c/h2\u003e\n \u003cp\u003eThe acetylation DA% and deacetylation DD% data reached for the different acquired chitosan besides that for the commercial one are presented in Table\u0026nbsp;(1)\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;(1)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eIt is assumed that the ratio relets the intensities of two bands near 1320 / 1420 presents a minor experimental error for evaluating the chitin deacetylation, despite of the method and the nature of the matter [\u003cspan class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e31\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe degrees of deacetylation, DD%, escalate as the decline in the number of the acetyl groups and attribute to the protonation of the -NH\u003csub\u003e2\u003c/sub\u003e groups on the carbon 2 (C2) position of the replicating D-glucosamine units. This proposing distinguished quality chitosan product [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eAccording to Joseph et.al and based on the data obtained for deacetylation, the extracted chitosan under consideration can be classified as a product with high deacetylation degree (HDD) (70% \u0026ndash; 99%) [\u003cspan class=\"CitationRef\"\u003e32\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eIt is reported that the deacetylation degree of the commercial chitosan ranges, mainly, from 74\u0026ndash;80% [\u003cspan class=\"CitationRef\"\u003e33\u003c/span\u003e]. It is worth to state that the purchased one and used for comparison in this study has DD % near 76%. Compared to the figures obtained in the present study, this value is comparable to the extracted chitosan which subjected to increasing deacetylation periods [Table\u0026nbsp;1].\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec21\" class=\"Section2\"\u003e\n \u003ch2\u003eScanning Electron Microscopy (SEM)\u003c/h2\u003e\n \u003cp\u003eThe microstructure of the shrimp shells, under consideration, as precursor for chitin and chitosan as well as the impact of each processing step on the morphology of every product were examined by SEM.\u003c/p\u003e\n \u003cp\u003eFigure (2-I) presents the topography of shrimp shell waste, under consideration, which indicates main four layers for the shell, namely, the epicuticle [A], the exocuticle [B], the endocuticle [C], and inner membrane [D]. The three former layers are observable as definite layers in the micrograph while the inner membrane is very thin, discontinuous, and hard to detect. The shell architecture looks to be fibrous. The thickness of the three layers is arranged as exocuticle\u0026thinsp;\u0026gt;\u0026thinsp;epicuticle\u0026thinsp;\u0026gt;\u0026thinsp;endocuticle. The same arrangement was reported by Xu et.al [\u003cspan class=\"CitationRef\"\u003e34\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eFigure (2)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eShrimp shells show a heterogeneous morphology distinguished by a compacted assembly with well-distinct chips-like shapes that have white spots. Additionally, the shell seems to possess a tough overlay with very rare pores which is attributed to the existence of protein and mineral components that appeared as white spots. Figures\u0026nbsp;(2-II) [\u003cspan class=\"CitationRef\"\u003e35\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e36\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe internal structure of chitin and chitosan was examined, also, by scanning electron microscope. Figures\u0026nbsp;(2, III-XVIII) presents the SEM photos of chitin, commercial and extracted chitosan with several magnifications and at various zones.\u003c/p\u003e\n \u003cp\u003eThe obtained chitin past demineralization and deproteinization processing of the shrimp shells possessed irregular smooth microstructures. Moreover, the micrograph presents blocky fiber arrays besides the uneven distinct horizontal fiber structures. Figures\u0026nbsp;(2-III). However, the topography of chitin and /or chitosan is dependent upon the type and the method of processing of the shells [\u003cspan class=\"CitationRef\"\u003e37\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eChitin is displaying, also, a compactly flattened morphology, containing round pores collection with thick walls surrounding the pores and the remains of the spouts within (Fig.\u0026nbsp;2-IV). The white cake-like locations in the shells are assumed to be substituted by the rounded pores as a result of the deletion of protein and calcium carbonates [CaCO\u003csub\u003e3\u003c/sub\u003e] crystals after the demineralization and deproteinization steps [\u003cspan class=\"CitationRef\"\u003e39\u003c/span\u003e]. Comparable remark was stated by Yen et al. (2009), [\u003cspan class=\"CitationRef\"\u003e41\u003c/span\u003e], Arbia et al. [\u003cspan class=\"CitationRef\"\u003e42\u003c/span\u003e], and Muzzarelli et al. [\u003cspan class=\"CitationRef\"\u003e43\u003c/span\u003e]. In this examined area of chitin, the pores sizes are ranged from 4.642 \u0026micro;m to 13.14 \u0026micro;m (Fig.\u0026nbsp;2-V).\u003c/p\u003e\n \u003cp\u003eAn outline SEM micrograph for the commercial chitosan is presented in Figure (2- VI) and pairs of detailed photos are depicted in Figure (2 VII-IX). The former image, with magnification 250x, demonstrates discontinuous, uneven blocky fiber structures, crumbly flakes, and even soft areas. At 1000x magnification for a selected slice of commercial chitosan, fibril arrangements can be differentiated, in addition to rough, disordered, disorganized, some cracks, and hardly detected very small pores with distorted topography Figure (2-VII). Moving to another area: lump and little white gatherings similar to that manifested in shrimp shell microstructure were detected in Figure (2-VIII). Also, at 1000x magnification, at an additional area of the commercial chitosan, a more or less even flattened surface with micro-pores can be manifested. Figures\u0026nbsp;(2, IX). Similar results were reported [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e44\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe architectures of the extracted chitosan were examined, also, by SEM and the micrographs with different magnifications, different areas, and those subjected to escalating deacetylation periods are presented in Fig. 2 [X- XVIII].\u003c/p\u003e\n \u003cp\u003eThe microstructures at different parts for chitosan generated from the deacetylation of chitin for 22 hours are presented in Fig.\u0026nbsp;2 (X, XI) with magnifications 800x \u0026amp; 2500x, respectively. At 800x magnification more or less even flattened surface besides regular rough smooth microstructure with very rare micro-pores can be manifested. Figures\u0026nbsp;(2-X). On the other hand, at 3000x and at other spots: folded surface, irregular pattern, with some longitudinal spaces in-between, little threads, and no obvious pores can be distinguished. Figures\u0026nbsp;(2-XI).\u003c/p\u003e\n \u003cp\u003eFor chitosan deacetylated for 30 hrs, the examination of the outcome at magnification 250x display asymmetric arrangements with irregular flacks. The surfaces are of various particle sizes and various lumpy, rough fissures, and irregular pattern, with some void spaces, little tiny threads, and no distinct pores can be differentiated Figure (2-XII).\u003c/p\u003e\n \u003cp\u003eAs the deacetylation degree after 30 hours recorded only\u0026thinsp;\u0026asymp;\u0026thinsp;78.23%, Table\u0026nbsp;2, the micrograph, at 1000x magnification in Figure (2-XIII) for the extract chitosan showed traces of non-deacetylated chitin. Examining other area, at 1500x magnification, showed uniformity brick like shape topography with trace of carbonate residues and micropores which can be hardly viewed [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e45\u003c/span\u003e] (Fig.\u0026nbsp;2- XIV).\u003c/p\u003e\n \u003cp\u003eThe microstructures at different parts of chitosan generated from the deacetylation of chitin for 40 hours are presented in Fig.\u0026nbsp;2 (XV-XVIII) with magnifications 250x, 1000x \u0026amp; 2000x, respectively. An overview at magnification 250x, for the extracted chitosan and deacetylated for 40hrs, the sample shows predominant smooth and plane region. A smooth polymer with chips-like plates and distinguished pores can be viewed also within this area (Fig.\u0026nbsp;2-XV).\u003c/p\u003e\n \u003cp\u003eExamination at another spot and at magnification 1000x indicates folded zone with unevenness structure, tough, irregular arrays, clear fissures and no definite pores can be distinguished. The micrograph discloses, also, a rough, disordered, disorganized and crumbled microstructure surface Figure (2-XVI).\u003c/p\u003e\n \u003cp\u003eApplying a higher magnification 2000x, reveals a soft and homogenous separated area demonstrating a plywood pattern structure. Traces of the white lumps as that of the shrimp shell can also be detected, in this area of examination. Moreover, pairs of micro-pores can be detected in this area (Fig.\u0026nbsp;2-XVII). The lack of homogeneity in the chitosan surface with a flattens area and roughness of another can be attributed to incomplete extraction of the chitosan from shrimp shells (Table\u0026nbsp;2).\u003c/p\u003e\n \u003cp\u003eThe micrograph of (Fig.\u0026nbsp;2-XVIII) at 2000x magnification in another part presents, also, that chitosan has an uneven and wavy identities which were affected by the deacetylation treatment of chitin. This can confirm the impact of deacetylation time on the properties and morphology of the chitosan output [\u003cspan class=\"CitationRef\"\u003e46\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eBased on the SEM examination the following remarks can be summarized:\u003c/p\u003e\n \u003cp\u003e- Generally, it can be confirmed that the extraction technique of chitosan displays variations in the shape and morphology of the final product.\u003c/p\u003e\n \u003cp\u003e- There is no entire elimination for all minerals, protein, and impurities from the precursor shrimp shells.\u003c/p\u003e\n \u003cp\u003e- The lack of homogeneity in chitosan\u0026rsquo;s surface with smooth segment and rough area is the indications of part split-up and signify the incomplete extraction process.\u003c/p\u003e\n \u003cp\u003e- The impact of the used chemical concentration and processing period applied influence the architectures microstructure of the final product.\u003c/p\u003e\n \u003cp\u003eThe spectra of Energy dispersive analyses of X-ray spectroscopy (EDX) for shrimp shell, extracted chitin, commercial chitosan, and deacetylated one for 30 hours were presented in Figure (3 a-d and Table\u0026nbsp;2). The elemental constitution of the four stuffs corroborated that the principal peaks in the four spectra are for carbon (C) and oxygen (O). The intensity of the carbon peaks was maximum for chitin, (Fig.\u0026nbsp;3b), followed by commercial and extracted chitosan, (c \u0026amp; d), while, the lowest peak intensity was for the shrimp shell (Fig.\u0026nbsp;3a). This can be attributed to the concentration of carbon contents after demineralization and deproteinization followed by dissolution due to deacetylation processes. It is clear from Figure (3 a-d) and Table\u0026nbsp;3 that the mass of calcium (Ca) % is found in the shrimp shell near 10% and at concentrations less than 1% in both chitin and two chitosans. Concerning the presence of traces of Ca in chitin and chitosan outputs, (Fig.\u0026nbsp;3, b, c \u0026amp;d), Li et. al., [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e] and Guan et. al., [\u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e], proposed that, the pureness of the extracted chitin and chitosan is based on its origin, demineralization and deproteinization applied techniques, chemicals used [\u003cspan class=\"CitationRef\"\u003e20\u003c/span\u003e] and processing period [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eFigure (3)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;(2)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eThis result proves the incapacity of diluted acid to remove all minerals from the shrimp shells, contrary to concentrated acids can leave just a few minerals traces.\u003c/p\u003e\n \u003cp\u003eIt is clear from Table\u0026nbsp;2, also, that there are insignificant variations in the composition of the commercial chitosan compared to the extracted chitosan under consideration. It worth to state that these very minute differences can be referred to shrimp origin, demineralization and deproteinization applied techniques, chemicals used processing period and even the shelf shipping conditions and period [\u003cspan class=\"CitationRef\"\u003e40\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e47\u003c/span\u003e] .\u003c/p\u003e\n \u003cp\u003eAccording to the United States Environmental Protection Agency (U.S. EPA), and the International Agency for Research on Cancer (IARC): arsenic, cadmium, chromium, lead, and mercury, due to their high degree of toxicity, these five elements classified among the main concern metals that are of great public health significance. They are all systemic toxicants that are known to provoke multiple organ damage, even at lower levels of exposure [\u003cspan class=\"CitationRef\"\u003e48\u003c/span\u003e]. Consequently, and based on EDX analysis, this confirms that the extracted chitosan under consideration, in connotation, would be a safe and non-toxic product when used in medical, pharmaceutical, biological, and food stuff industries.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec22\" class=\"Section2\"\u003e\n \u003ch2\u003eUltraviolet-Visible Spectroscopic Analyses\u003c/h2\u003e\n \u003cp\u003eThe Ultraviolet-Visible (UV\u0026ndash;Vis) spectra for extracted chitosan acquired from chitin deacetylated for 22 hrs, 30 hrs, 36 hrs, 40 hrs, and commercial chitosan, are presented in Figure (4). The UV\u0026ndash;Vis spectra for each stuff display distinguishing absorption bands. Table\u0026nbsp;(3) depicts the absorption maximum for the extracted chitosan generated from deacetylation for 22 hrs (CHI); 30 hrs (CHII); 36 hrs (CHIII), 40 hrs (CHIV), and commercial chitosan (CHC).\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eFigure (4)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003eThe absorption spectra of UV\u0026ndash;Vis for the five stuffs are comparable and allocated peaks \u0026lambda; at 238, 245, 248, 242, and 242 nm for extracted chitosan acquired from deacetylation for 22 hrs, 30 hrs, for 36 hrs and 40 hrs and for CHC respectively. Even they differ in their intensities, it should be stated that the extracted chitosan generated after chitin deacetylation for 40 hrs has a third peak at \u0026lambda; 346 nm. It was reported that the peak between 300\u0026ndash;370 nm is chrematistic for chitosan [\u003cspan class=\"CitationRef\"\u003e49\u003c/span\u003e]. Little bite shift can happen to the low limit at \u0026lambda; 290 nm. On the same trend, the peak at \u0026lambda; 300\u0026ndash;360 nm contributes to the absorption linked to the direct electronic \u0026pi;-d orbitals and is entitled as the Soret band [\u003cspan class=\"CitationRef\"\u003e50\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe sharp peaks for chitosan in the UV -Vis can verify their promise usages in waste water handling, nanoparticle invention and others [\u003cspan class=\"CitationRef\"\u003e51\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;(3)\u003c/strong\u003e\u003c/p\u003e\n \u003cdiv id=\"Sec23\" class=\"Section3\"\u003e\n \u003ch2\u003eThermal Characterizations\u003c/h2\u003e\n \u003cp\u003eThe Thermogravimetric analysis (TGA) curves, the mass changes TG in % versus sample temperature, \u0026deg;C, are applied to present the changes in material composition and its thermal stability. On parallel, DTG curves apply to ascertain the number of thermal consequences to which the material has been exposed, since each DTG peak, at a given temperature provides the rate of mass loss (mg/min) through its temperature range, (\u003cem\u003eTon, Tmax., Toff\u003c/em\u003e), where \u003cem\u003eTon\u003c/em\u003e, is the temperature of onset mass loss; \u003cem\u003eToff\u003c/em\u003e is the temperature of offset mass loss and \u003cem\u003eTmax\u003c/em\u003e is the temperature of the maximum mass loss rate within that peak. Thermogravimetric analyses (TG \u0026amp; DTG) were achieved systematically for commercial chitosan (CHC), for extracted chitosan intended from increasing deacetylation periods for: 22 hrs (CHI); 30 hrs (CHII); 36 hrs (CHIII), and 40 hrs (CHIV) under the same analyses conditions. The thermal analyses for the commercial chitosan were performed for the sake of comparison. The data acquired are presented in Figure (5) and Table (4).\u003c/p\u003e\n \u003cp\u003eIt is claim that the chitosan polymer, in general, displayed four significant mass loss steps attributed to: water moisture loss, degradation of the organic moiety, including the protein remained in chitosan past the all-extraction steps, the decarboxylation of calcium carbonate, degradation of the inorganic matters and/or recrystallization of any amorphous inorganic substances. Similar trend was reported for chitin [\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e52\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eThe TG curve for commercial chitosan demonstrates two steps of the polymer degradation. The first step began from 44.66\u0026deg;C up to 158.91\u0026deg;C with mass loss 6.08%. The corresponding DTG peak exhibits onset at 48.10\u0026deg;C, the temperature of the maximum mass loss rate within that peak at 87.24\u0026deg;C, and offset at 131.89\u0026deg;C with mass loss at a maximum of 7.09%. This mass loss is attributed to the water physically adsorbed inner and at the surface of CHF. The second step with a high mass loss of 49.97% started at 146.13\u0026deg;C and ended at 605.61\u0026deg;C. The parallel DTG curve displays onset at 278.83\u0026deg;C and offset at 323.87\u0026deg;C with swift mass loss of 33.17% at \u003cem\u003eTmax\u003c/em\u003e 305.26\u0026deg;C signifying the decomposition of the polysaccharide and protein moieties [\u003cspan class=\"CitationRef\"\u003e6\u003c/span\u003e] Figure (5), Table\u0026nbsp;(4).\u003c/p\u003e\n \u003cp\u003eThe chitosan CHI, CHIII, and CHIV are disclosed in the same manner as commercial ones, and undergo the two steps of mass loss. On the other hand, the chitosan CHII showed three steps of mass loss. The additional third step exhibits onset at 436.29\u0026deg;C and offset at 496.74\u0026deg;C with a mass loss of 2.196% at \u003cem\u003eTmax\u003c/em\u003e 476.32\u0026deg;C. This step can be attributed to the thermal dehydroxylation of calcium hydroxide [Ca (OH)\u003csub\u003e2\u003c/sub\u003e] formed by increasing the deacetylation time, and took place in the region between 400\u0026deg;C and 600\u0026deg;C, followed by the decarboxylation of the formed carbonated phases and calcite up to 600\u0026deg;C according to Eq.\u0026nbsp;(2) \u0026amp; Eq.\u0026nbsp;(3), respectively [\u003cspan class=\"CitationRef\"\u003e53\u003c/span\u003e, \u003cspan class=\"CitationRef\"\u003e54\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cimg 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\" width=\"451\" height=\"127\"\u003e\u003c/p\u003e\n \u003cp\u003eBased on thermal analyses data, it can be deduced that a process of chitosan extraction has an impact on their thermal stability. It is clear from table (4) that the chitosan CHIV is most thermally stable compare to the other ones and even to the commercial chitosan. The chitosan II loses its mass gradually, past three degradations showing lowest mass loss i.e. 23.12%. Similar trends were previously published [\u003cspan class=\"CitationRef\"\u003e55\u003c/span\u003e\u0026ndash;\u003cspan class=\"CitationRef\"\u003e57\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003eParallel to the thermal analysis (DTA\u0026amp;DTG), the differential scanning calorimetry (DSC) curves for the different extracted chitosan were performed under Nitrogen atmosphere [Figure (5)]. Two decomposition stages for the all-chitosan preparations were disclosed which can be briefed as follows: the first one at ~\u0026thinsp;80\u0026deg;C, compared to the commercial CHC at ~\u0026thinsp;86\u0026deg;C and can be attributed to an endothermic reaction comprises the release of moisture surface water and hydrogen-bonded water. The second is a strongly exothermic peak that disclosed between 304\u0026deg;C \u0026ndash; 313\u0026deg;C compared to 309\u0026deg;C for chitosan CHC. This degradation second step is attributed to the degradation of the rest cross-linked chitosan skeleton [\u003cspan class=\"CitationRef\"\u003e58\u003c/span\u003e]. Hence, it can be noted that the thermal decomposition of the chitosan polymers, under consideration, happened in two marked steps. Based on the data acquired for the TGA, TGD, and DSC analyses, it can claim that the extracted chitosan from shrimp is characterized by acceptable thermal stability and can, practically, represent a valuable and cost-effective natural biosorbent for some hazardous and radioactive waste streams, in addition, to the other numerous agriculture and medical applications.\u003c/p\u003e\n \u003cp\u003eThe thermal destruction progression of chitosan leans to be quiet beyond 356.74\u0026deg;C. Though, this was a minor descending inclination near 600\u0026deg;C, and can be attributed to the residual carbon content [\u003cspan class=\"CitationRef\"\u003e59\u003c/span\u003e], and comprises 13.01%, 13.22%, 10.07% and 9.38% for CHI, CHII, HIII and CHIV, respectively and comparable to commercial one (CHC), Figure (5).\u003c/p\u003e\n \u003cp\u003eHence, it can be noted that the thermal decomposition of the chitosan polymers, under consideration, happened in two marked steps. Based on the data acquired for the TGA, TGD, and DSC analyses it can be claimed that the extracted chitosan from shrimp shell is characterized by an acceptable thermal stability and can, practically, represent a valuable and cost-effective natural biosorbent for some hazardous and radioactive waste streams, in addition, to the other numerous agriculture, industrial and medical applications.\u003c/p\u003e\n \u003cp\u003eAccording to the data obtained, based on thermal analyses, the following conclusions can be summarized:\u003c/p\u003e\n \u003cp\u003e- The method of chitosan extraction has an impact on their thermal stability.\u003c/p\u003e\n \u003cp\u003e-The water moisture loss happened in between ~\u0026thinsp;44\u0026deg;C up to ~\u0026thinsp;158\u0026deg;C comparable to that of commercial one Table\u0026nbsp;(4).\u003c/p\u003e\n \u003cp\u003e- The mass loss percentages due to water moisture depletion are in range from 5.61% \u0026minus;\u0026thinsp;8.77% with mean value 7.31% which is not far from the commercial chitosan (7.09%).\u003c/p\u003e\n \u003cp\u003e- The mass losses next to the first step, are largely, assigned to a complicated processes involving: dehydration of the polysaccharide rings, depolymerization and decomposition of the deacetylated moieties of chitosan, besides, to dehydroxylation and destruction processes.\u003c/p\u003e\n \u003cp\u003e- As of the extensive magnitude of inter- and intramolecular hydrogen bonding in chitosan; accordingly, it needs additional energy to fracture [\u003cspan class=\"CitationRef\"\u003e60\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e-The acceptable thermal stability of the developed chitosan, under consideration recommend it as effective biosorbent for treatment of some hazardous and radioactive waste streams, even, at temperature near 100\u0026deg;C.\u003c/p\u003e\n \u003cp\u003e-The final mass loss for the chitosan is above 600\u003csup\u003e\u0026deg;\u003c/sup\u003eC which assumed to be due to the decomposition of the traces of CaCO\u003csub\u003e3\u003c/sub\u003e decomposed to CaO and CO\u003csub\u003e2\u003c/sub\u003e [\u003cspan class=\"CitationRef\"\u003e61\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e-The adequate thermal stability of chitosan under consideration can be attributed to the intramolecular and intermolecular hydrogen bonds [\u003cspan class=\"CitationRef\"\u003e62\u003c/span\u003e].\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eTable\u0026nbsp;(4)\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eFigure (5)\u003c/strong\u003e\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003eBased on the experimental data reached, the following conclusions can be reported: The conventional chemical method applied is a reliable, straightforward, and cost-effective technique for extracting chitosan from shrimp shell waste due to the cheap chemical used, non-sophisticate, and consistent processes. Practically, increasing the deacetylation time of chitin significantly influences the Degree of Deacetylation (DD) of chitosan and, consequently, affects its spectroscopic characteristics. Moreover, the spectroscopic tools used are effective for indicating the impact of various deacetylation times on the configuration of the extracted chitosan. Additionally, the results reached confirm that the extracted chitosan, under consideration, is pure, ultrafine, and non-toxic, with an acceptable degree of deacetylation (DD) of nearly 80%. The extracted chitosan exhibits acceptable heat resistance, showing no thermal degradation until it reaches 300\u0026deg;C. This resistance is comparable to that of commercial chitosan. The configuration of chitosan closely resembles that of cellulose, with the distinction that the hydroxyl group at the C-2 position in cellulose is replaced by an amino group in chitosan. This -NH\u003csub\u003e2\u003c/sub\u003e group enables chitosan to effectively scavenge pollutants, such as heavy metals and radionuclides, from waste solutions.\u003c/p\u003e \u003cp\u003eAs waste recycling becomes of global interest, shrimp shell wastes can be utilized more effectively by extracting chitosan, which can then be applied in a wide variety of everyday applications. From an environmental point of view, stimulating marine biomass can yield significant economic and environmental benefits for industries, including the fishery sector. Utilizing shrimp waste as a source of chitosan extraction on an industrial scale would help address the accumulation of waste generated by processing plants, presenting a challenge for both the industry and community health.\u003c/p\u003e \u003cp\u003eFuture projects are planned to explore the combination of the extracted chitosan with certain cellulose derivatives, either as a backbone or a cross-linking agent. These combinations are expected to produce various hydrogel products with promising economic value that can be applied in many areas of daily life. It is recommended, also, that more studies can focus on investigating the antimicrobial and antioxidant properties of chitosan extracted from Egyptian shrimp shell wastes.\u003c/p\u003e "},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eCompliance with ethical standards conflict of interest\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eOn behalf of all authors, the corresponding author affirms that there is no conflict of interest to publish this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e: The authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e: All the authors listed have approved the manuscript and consented for publication.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e: The authors state that the present work is in compliance with ethical standards. All the authors listed have approved the manuscript and consented to participate.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e: Data sharing not applicable to this article as all datasets were generated or analyzed during the current study.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding Open Access\u003c/strong\u003e This article is licensed under (STDF). Egyptian institutions are participating in the transformative agreement between Springer Nature and Science, Technology \u0026amp; Innovation Funding Authority (STDF) in cooperation with Egyptian Knowledge Bank (EKB). This agreement covers all the public, private and national universities, as well as the research centers related to the Ministry of Higher Education and Scientific Research and all other governmental ministries in Egypt.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eM.E.T designed the experiment, organized the experimental process, participated in the experiments and wrote the paper with S.B.E. S.N.G, participated in the experiments. All authors have read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgment\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors express their cordial thanks to the Administration of the National Research Centre, Egypt, for all possible facilities to accomplish this work.\u003c/p\u003e\n\u003cp\u003eThe authors, also, gratefully acknowledge Radioisotope Department, Egyptian Atomic Energy Authority for their scientific co-operation to complete this work.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eMiranda SP, Garnica O, Lara-Sagahon VA, C\u0026aacute;rdenas G (2004) Water vapour permeability and mechanical properties of chitosan composite films. J Chil Chem Soc 49: 173-178. 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J Inorg Organomet Polym 21: 69\u0026ndash;80. doi10.1007/s10904-010-9421-2\u003c/li\u003e\n \u003cli\u003eYu H, Xu X, Xia Y, Pan M, Zarshad N, Pang B, Ur Rahman A, Wu M, and Ni H (2020) Synthesis of a novel modified chitosan as an intumescent flame retardant for epoxy resin. e-Polymers 20: 303\u0026ndash;316. doi.org/10.1515/epoly-2020-0036\u003c/li\u003e\n \u003cli\u003eAl-Sou\u0026rsquo;oda Kh, Abu-Falahaa R, Al-Remawib M (2013) Surface activity of some low molecular weight chitosan derivatives. Jordan Journal of Chemistry 8(1): 1-17\u003c/li\u003e\n \u003cli\u003eShamshina JL, Barber PS, Gurau G, Griggs CS, Rogers RD (2016) Pulping of crustacean waste using ionic liquids: To extract or not to extract? ACS Sustain Chem Eng 4 (11): 6072\u0026ndash;6081. doi.org/10.1021/acssuschemeng.6b01434\u003c/li\u003e\n \u003cli\u003eTana W, Li Q, Dong F, Zhang J, Luan F, Wei L, Chen Y, Guo Z (2018) Novel cationic chitosan derivative bearing 1, 2, 3-triazolium and pyridinium: Synthesis, characterization, and antifungal property. Carbohydrate polymer 182: 180-187. doi.org/10.1016 /j.carpol.2017.11.023\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables 1 to 3 are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ccjo","sideBox":"Learn more about [BMC Chemistry](https://bmcchem.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ccjo/default.aspx","title":"BMC Chemistry","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"shrimp shell waste, chemical extraction of chitosan, degree of deacetylation, FTIR-ART, SEM-EDX, UV-Vis., TG, DTG, DSC","lastPublishedDoi":"10.21203/rs.3.rs-5723322/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-5723322/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eA conventional chemical method was applied for the extraction of chitosan (CH) from shrimp shell wastes (SSWs) in three stages: 1. Demineralization: SSWs were treated with HCl to remove minerals. 2. Deproteinization: NaOH was used to eliminate proteins from the demineralization shells. 3: Deacetylation: The chitin (CT) obtained from stage 2 was converted to chitosan in alkaline medium using NaOH.\u003c/p\u003e \u003cp\u003eThis study aims to demonstrate the impact of varying deacetylation times on chitosan surface morphology, elemental composition, thermal resistance, structural configuration, and deacetylation degree (DD). Variable techniques including UV-visible spectroscopy, Fourier Transformed Infra-Red (FTIR-ATR), Thermogravimetry (TG/DTG), Scanning Electron Microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX) analyses were employed to analyze how increased deacetylation periods affect the characterization of the products.\u003c/p\u003e \u003cp\u003eThe FTIR spectra showed a notable similarity between all extracted chitosan processed with increasing deacetylation time and the commercial one. Moreover, the results revealed that all the extracted chitosan samples acquired DD values, based on FTIR-ATR analysis, are comparable to that of commercial ones i.e. 79.54%, 78.23%, 74.81%, and 76.56% for deacetylated times of 22 hrs, 30 hrs, 36 hrs, and 40 hours, respectively are comparable to that of the commercial chitosan (76.1%).\u003c/p\u003e \u003cp\u003eFurthermore, the EDX analysis confirms that the extracted chitosan is non-toxic product, making it suitable for various applications, including biological and medical uses.\u003c/p\u003e","manuscriptTitle":"Spectroscopic Approaches for Structural Analysis of Extracted Chitosan Generated from Chitin Deacetylated for Escalated Periods","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-01 10:49:54","doi":"10.21203/rs.3.rs-5723322/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-13T15:28:05+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-05-13T15:24:46+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-04-27T11:42:00+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"339657812024176152145728259789017697622","date":"2025-04-27T09:23:24+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"40433299665106431600080274863005643634","date":"2025-04-09T17:28:29+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-03-31T10:19:18+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-31T10:00:27+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Chemistry","date":"2025-03-28T16:04:54+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-chemistry","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"ccjo","sideBox":"Learn more about [BMC Chemistry](https://bmcchem.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/ccjo/default.aspx","title":"BMC Chemistry","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"748c4a85-35c4-410f-a21d-37be00c5b3a2","owner":[],"postedDate":"April 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-07-21T16:00:34+00:00","versionOfRecord":{"articleIdentity":"rs-5723322","link":"https://doi.org/10.1186/s13065-025-01558-3","journal":{"identity":"bmc-chemistry","isVorOnly":false,"title":"BMC Chemistry"},"publishedOn":"2025-07-16 15:57:01","publishedOnDateReadable":"July 16th, 2025"},"versionCreatedAt":"2025-04-01 10:49:54","video":"","vorDoi":"10.1186/s13065-025-01558-3","vorDoiUrl":"https://doi.org/10.1186/s13065-025-01558-3","workflowStages":[]},"version":"v1","identity":"rs-5723322","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-5723322","identity":"rs-5723322","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}