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<p>The organic dyes discharged from industrial effluents create major environmental issues in runoff surface water bodies. The removal of these dyes from discharged effluents, using biomass resources, has long been proposed as a sustainable water treatment technology. In the present work, chitosan derived from crab shell textures (CS) have individually impregnated with cashew nut stem biochar (CWBC), <i>Eucalyptus</i> wood biochar (RSBC), and <i>Cassia fistula</i> stem biochar (KBC) and finally hybrid with zinc oxide (ZnO). Both chitosan and biochar are biodegradable in nature and derived from renewable sources, making these composites environmental friendly. Further, the amine groups in chitosan, combined with the porous structure of biochar, increase the binding sites, enabling effective dye removal in wastewater treatment. The synthesized chitosan-biochars (CSBC) and its hybrid zinc oxide composites (CSBCZnO) have been characterized by FTIR, SEM, XRD, and TGA to provide detailed insights into chemical composition, surface morphology, and pore structure, which are crucial for understanding adsorption properties and efficiency. Accordingly, the surface area, pore volume, and pore diameter of the composite were found to be 428.724 m<sup>2</sup>/g, 0.705&#xa0;cc/g, and 3.318&#xa0;nm, respectively. The batch adsorption experiments were carried out for both CSBC and CSBCZnO composites to remove of methyl orange (MO) dyes from aqueous solutions. The adsorption of dyes was evaluated by increasing the adsorbent doses from 0.2 to 1.2&#xa0;g/L at a constant temperature and a basic pH of 9. The kinetic studies of adsorbents were carried out for pseudo-first-order, pseudo-second-order, and Langmuir and Freundlich isotherms. The amount of adsorption of the composites of CSCWZnO, CSRSZnO, and CSKZnO was found to be 263.15, 270.21, and 263.15&#xa0;mg/g, respectively, and its correlation coefficient <i>R</i><sup>2</sup> was found to be 0.980, 0.999, and 0.980. The values of <i>K</i><sub><i>F</i></sub> of these composites were found to be higher than the <i>K</i><sub><i>L</i></sub> values, which highlighted that the Freundlich isotherm model is the best suited model for the adsorption of MO dyes on CSBC and CSBCZnO composites, and hence, it has followed chemisorption. Thus, the improved adsorption capacity of ZnO hybrids may offer solutions for real-world applications in water treatment. </p> Graphical Abstract <p></p>

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Efficient adsorption of methyl orange dye by novel chitosan-biochar hybrid zinc oxide composites

  • 期刊论文

  • 发表日期：

    2025年4月20日

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  • Prabhu C.,
  • Rengasamy M.,
  • Surendiran T.,
  • Venkatesan G

摘要

The organic dyes discharged from industrial effluents create major environmental issues in runoff surface water bodies. The removal of these dyes from discharged effluents, using biomass resources, has long been proposed as a sustainable water treatment technology. In the present work, chitosan derived from crab shell textures (CS) have individually impregnated with cashew nut stem biochar (CWBC), Eucalyptus wood biochar (RSBC), and Cassia fistula stem biochar (KBC) and finally hybrid with zinc oxide (ZnO). Both chitosan and biochar are biodegradable in nature and derived from renewable sources, making these composites environmental friendly. Further, the amine groups in chitosan, combined with the porous structure of biochar, increase the binding sites, enabling effective dye removal in wastewater treatment. The synthesized chitosan-biochars (CSBC) and its hybrid zinc oxide composites (CSBCZnO) have been characterized by FTIR, SEM, XRD, and TGA to provide detailed insights into chemical composition, surface morphology, and pore structure, which are crucial for understanding adsorption properties and efficiency. Accordingly, the surface area, pore volume, and pore diameter of the composite were found to be 428.724 m2/g, 0.705 cc/g, and 3.318 nm, respectively. The batch adsorption experiments were carried out for both CSBC and CSBCZnO composites to remove of methyl orange (MO) dyes from aqueous solutions. The adsorption of dyes was evaluated by increasing the adsorbent doses from 0.2 to 1.2 g/L at a constant temperature and a basic pH of 9. The kinetic studies of adsorbents were carried out for pseudo-first-order, pseudo-second-order, and Langmuir and Freundlich isotherms. The amount of adsorption of the composites of CSCWZnO, CSRSZnO, and CSKZnO was found to be 263.15, 270.21, and 263.15 mg/g, respectively, and its correlation coefficient R2 was found to be 0.980, 0.999, and 0.980. The values of KF of these composites were found to be higher than the KL values, which highlighted that the Freundlich isotherm model is the best suited model for the adsorption of MO dyes on CSBC and CSBCZnO composites, and hence, it has followed chemisorption. Thus, the improved adsorption capacity of ZnO hybrids may offer solutions for real-world applications in water treatment.

Graphical Abstract