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<p>This work presents the synthesis of a chitosan-based nanocomposite of crosslinked chitosan-citrate/SnO<sub>2</sub> nanoparticles (CTN-CT/SnO<sub>2</sub>) for methyl blue (MB) dye removal from aqueous solutions. Box-Behnken design (BBD) was implemented to examine the impact of three variables on the adsorption of MB dye: A: CTN-CT/SnO<sub>2</sub> dose (0.02–0.08&#xa0;g), B: pH (4–10), and C: time (10–30) min. The BET surface area of the CTN-CT/SnO<sub>2</sub> nanocomposite was determined to be 9.90&#xa0;m<sup>2</sup>/g. Furthermore, the mean pore diameter was 7.05&#xa0;nm, and the total pore volume was measured to be 0.0174&#xa0;cm<sup>3</sup>/g. The CTN-CT/SnO<sub>2</sub> nanocomposite demonstrates predominantly polycrystalline properties, as evidenced by its average crystallite size of 23.76&#xa0;nm. Kinetic modeling of MB dye adsorption was conducted using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The results demonstrate that the pseudo-first-order kinetic model best describes the MB adsorption by CTN-CT/SnO<sub>2</sub>. Adsorption isotherm models, including Langmuir, Dubinin–Radushkevich, Freundlich, and Temkin, were applied to understand the MB adsorption behavior. The Freundlich model exhibited the best fit (<i>R</i><sup>2</sup> = 0.98), suggesting a multilayer adsorption process. Thermodynamic analysis revealed negative Gibbs free energy values (Δ<i>G</i>° = − 8.137 to − 12.587&#xa0;kJ/mol), indicating the spontaneity of the adsorption. Additionally, positive values for enthalpy (Δ<i>H</i>° = 36.086&#xa0;kJ/mol) and entropy (Δ<i>S</i>° = 0.1483&#xa0;kJ/molK) suggest that the process is endothermic and accompanied by an increase in disorder at the interface. The optimal conditions for maximal MB elimination (96.53%) were determined by the BBD model findings, which identified a pH of 9, a CTN-CT/SnO<sub>2</sub> dose of 0.045&#xa0;g, and a contact duration of 27.8&#xa0;min. The maximal absorption capacity of the CTN-CT/SnO<sub>2</sub> nanocomposite at 25&#xa0;°C for the MB dye was 511.92&#xa0;mg/g. The hydrogen bonding, electrostatic interaction, <i>n</i>–<i>π</i> interaction, and Yoshida H-bonding were postulated as the mechanisms behind the adsorption of MB dye onto the CTN-CT/SnO<sub>2</sub> nanocomposite. The work presents a highly efficient CTN-CT/SnO<sub>2</sub> nanocomposite as a potential adsorbent for effectively eliminating organic dye from water-based solutions.</p>

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Advanced biomaterial of crosslinked chitosan-citrate/SnO2 nanoparticles for organic dye removal: insight into physicochemical and adsorption characteristics

  • 期刊论文

  • 发表日期：

    2025年5月17日

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  • Ahmed Saud Abdulhameed,
  • Samaa Abdullah,
  • Alaa A. Al-Masud,
  • Mahmoud Abualhaija,
  • Sameer Algburi

摘要

This work presents the synthesis of a chitosan-based nanocomposite of crosslinked chitosan-citrate/SnO2 nanoparticles (CTN-CT/SnO2) for methyl blue (MB) dye removal from aqueous solutions. Box-Behnken design (BBD) was implemented to examine the impact of three variables on the adsorption of MB dye: A: CTN-CT/SnO2 dose (0.02–0.08 g), B: pH (4–10), and C: time (10–30) min. The BET surface area of the CTN-CT/SnO2 nanocomposite was determined to be 9.90 m2/g. Furthermore, the mean pore diameter was 7.05 nm, and the total pore volume was measured to be 0.0174 cm3/g. The CTN-CT/SnO2 nanocomposite demonstrates predominantly polycrystalline properties, as evidenced by its average crystallite size of 23.76 nm. Kinetic modeling of MB dye adsorption was conducted using pseudo-first-order, pseudo-second-order, and intra-particle diffusion models. The results demonstrate that the pseudo-first-order kinetic model best describes the MB adsorption by CTN-CT/SnO2. Adsorption isotherm models, including Langmuir, Dubinin–Radushkevich, Freundlich, and Temkin, were applied to understand the MB adsorption behavior. The Freundlich model exhibited the best fit (R2 = 0.98), suggesting a multilayer adsorption process. Thermodynamic analysis revealed negative Gibbs free energy values (ΔG° = − 8.137 to − 12.587 kJ/mol), indicating the spontaneity of the adsorption. Additionally, positive values for enthalpy (ΔH° = 36.086 kJ/mol) and entropy (ΔS° = 0.1483 kJ/molK) suggest that the process is endothermic and accompanied by an increase in disorder at the interface. The optimal conditions for maximal MB elimination (96.53%) were determined by the BBD model findings, which identified a pH of 9, a CTN-CT/SnO2 dose of 0.045 g, and a contact duration of 27.8 min. The maximal absorption capacity of the CTN-CT/SnO2 nanocomposite at 25 °C for the MB dye was 511.92 mg/g. The hydrogen bonding, electrostatic interaction, n–π interaction, and Yoshida H-bonding were postulated as the mechanisms behind the adsorption of MB dye onto the CTN-CT/SnO2 nanocomposite. The work presents a highly efficient CTN-CT/SnO2 nanocomposite as a potential adsorbent for effectively eliminating organic dye from water-based solutions.