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<p>Chitosan-based adsorbents are limited by low adsorption capacity and poor stability in heavy metal remediation. To address these limitations, an acrylic acid-grafted chitosan composite (CTS-g-AAC) was synthesized via a two-step method involving acrylic acid grafting and glutaraldehyde cross-linking. The Cu<sup>2+</sup> adsorption performance and mechanism of CTS-g-AAC were systematically investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) characterizations confirmed the porous structure of CTS-g-AAC, which favors mass transfer, successful grafting of acrylic acid, and coordination-chelating interactions between Cu<sup>2+</sup> and surface functional groups including -NH₂, -OH and -COO⁻. Under optimal conditions (pH 4, initial Cu<sup>2+</sup> concentration 200&#xa0;mg·L⁻¹, temperature 323&#xa0;K, and adsorption time 4&#xa0;h), the maximum Cu<sup>2+</sup> adsorption capacity of CTS-g-AAC reached 192.96&#xa0;mg·g⁻¹. Pseudo-second-order kinetic model fitting demonstrated that chemisorption dominated the rate-limiting step of adsorption, and the excellent fit of isothermal data to the Langmuir model further verified the monolayer adsorption characteristic of the process. Thermodynamic results showed negative ΔG, positive ΔH (22.28&#xa0;kJ·mol⁻¹) and positive ΔS, demonstrating that the adsorption process was spontaneous, endothermic and accompanied by increased system disorder. Multi-dimensional evidence confirmed that coordination-chelating chemisorption is the dominant mechanism. CTS-g-AAC exhibits great potential for Cu<sup>2+</sup> removal from wastewater, and the proposed two-step modification strategy provides a feasible approach to enhance the performance of chitosan-based adsorbents for heavy metal remediation.</p>

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Acrylic acid grafted chitosan composite with enhanced Cu2+ adsorption performance: synthesis, characterization, kinetics and thermodynamics

  • 期刊论文

  • 发表日期：

    2026年6月25日

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  • Tong Zhang,
  • Mingyan Dang,
  • Xutong Zhang,
  • Chengzhi Jiang,
  • Yichen Li

摘要

Chitosan-based adsorbents are limited by low adsorption capacity and poor stability in heavy metal remediation. To address these limitations, an acrylic acid-grafted chitosan composite (CTS-g-AAC) was synthesized via a two-step method involving acrylic acid grafting and glutaraldehyde cross-linking. The Cu2+ adsorption performance and mechanism of CTS-g-AAC were systematically investigated. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) characterizations confirmed the porous structure of CTS-g-AAC, which favors mass transfer, successful grafting of acrylic acid, and coordination-chelating interactions between Cu2+ and surface functional groups including -NH₂, -OH and -COO⁻. Under optimal conditions (pH 4, initial Cu2+ concentration 200 mg·L⁻¹, temperature 323 K, and adsorption time 4 h), the maximum Cu2+ adsorption capacity of CTS-g-AAC reached 192.96 mg·g⁻¹. Pseudo-second-order kinetic model fitting demonstrated that chemisorption dominated the rate-limiting step of adsorption, and the excellent fit of isothermal data to the Langmuir model further verified the monolayer adsorption characteristic of the process. Thermodynamic results showed negative ΔG, positive ΔH (22.28 kJ·mol⁻¹) and positive ΔS, demonstrating that the adsorption process was spontaneous, endothermic and accompanied by increased system disorder. Multi-dimensional evidence confirmed that coordination-chelating chemisorption is the dominant mechanism. CTS-g-AAC exhibits great potential for Cu2+ removal from wastewater, and the proposed two-step modification strategy provides a feasible approach to enhance the performance of chitosan-based adsorbents for heavy metal remediation.