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<p>Heavy metal contamination in wastewater remains a critical environmental concern. This study investigates the adsorption performance of pyridine-functionalized chitosan (CS-PY) for the removal of arsenic (As) and antimony (Sb) from aqueous solutions. Batch experiments were conducted using unmodified chitosan (CS) and CS-PY under varying conditions, including initial metal ion concentration, pH, contact time, temperature, and the presence of coexisting anions. Kinetic and equilibrium analyses indicated that adsorption followed the pseudo-second-order and Langmuir isotherm models. CS-PY exhibited significantly enhanced adsorption capacities of 32.49 mg/g for As and 48.31 mg/g for Sb, compared to 21.02 mg/g and 31.12 mg/g for CS, respectively. Thermodynamic studies confirmed that the adsorption process is spontaneous, endothermic, and primarily governed by physisorption, with Gibbs free energy (ΔG°) values ranging from -2.476 to -3.186 kJ/mol for As and -3.945 to -5.071 kJ/mol for Sb, and enthalpy changes (ΔH°) of 4.832 kJ/mol for As and 7.345 kJ/mol for Sb. The presence of common competing anions (NO<sub>3</sub><sup>−</sup>, Cl<sup>−</sup>, and SO<sub>4</sub><sup>2−</sup>) had minimal impact on adsorption efficiency, demonstrating the strong selectivity of CS-PY. These findings establish CS-PY as a highly effective adsorbent for As and Sb removal, offering a promising solution for water purification.</p>

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Pyridine-Functionalized Chitosan for Arsenic and Antimony Removal: Adsorption Kinetics and Thermodynamics

  • 期刊论文

  • 发表日期：

    2025年4月26日

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  • Mostafa Y. Nassar,
  • Tariq Z. Abolibda,
  • Sobhi M. Gomha,
  • Amany A. Asaad,
  • Mohamed S. S. Adam,
  • Emad M. Masoud,
  • Ibrahim Alfurayj,
  • Ahmed Khalil

摘要

Heavy metal contamination in wastewater remains a critical environmental concern. This study investigates the adsorption performance of pyridine-functionalized chitosan (CS-PY) for the removal of arsenic (As) and antimony (Sb) from aqueous solutions. Batch experiments were conducted using unmodified chitosan (CS) and CS-PY under varying conditions, including initial metal ion concentration, pH, contact time, temperature, and the presence of coexisting anions. Kinetic and equilibrium analyses indicated that adsorption followed the pseudo-second-order and Langmuir isotherm models. CS-PY exhibited significantly enhanced adsorption capacities of 32.49 mg/g for As and 48.31 mg/g for Sb, compared to 21.02 mg/g and 31.12 mg/g for CS, respectively. Thermodynamic studies confirmed that the adsorption process is spontaneous, endothermic, and primarily governed by physisorption, with Gibbs free energy (ΔG°) values ranging from -2.476 to -3.186 kJ/mol for As and -3.945 to -5.071 kJ/mol for Sb, and enthalpy changes (ΔH°) of 4.832 kJ/mol for As and 7.345 kJ/mol for Sb. The presence of common competing anions (NO3−, Cl−, and SO42−) had minimal impact on adsorption efficiency, demonstrating the strong selectivity of CS-PY. These findings establish CS-PY as a highly effective adsorbent for As and Sb removal, offering a promising solution for water purification.