双交联壳聚糖基水凝胶的构建及其对Cu²⁺/Cd²⁺的高效吸附与再生机制研究

Preparation of Double-Crosslinked Chitosan-Based Hydrogel and Study on Its Efficient Adsorption of Cu²⁺/Cd²⁺ and Regeneration Mechanism

摘要: 本研究通过自由基聚合与冻融循环协同策略，成功制备了一种双交联壳聚糖基水凝胶吸附剂(CISP)。该材料以衣康酸和甲基丙烯磺酸钠为接枝单体，通过化学交联剂(N,N’-亚甲基双丙烯酰胺)和物理交联骨架(聚乙烯醇)构建三维网络结构。系统研究了CISP对Cu²⁺与Cd²⁺的吸附行为及机理，并通过FTIR、XPS、SEM-EDS等表征手段揭示了其功能基团(-COO⁻, $-S{O}_3^{-}$ , -OH)与金属离子的配位作用。实验表明：在pH 3~5、25℃、投加量3 g/L条件下，CISP对Cu²⁺与Cd²⁺的去除率分别达92.9%和91.2%；吸附过程符合伪二级动力学模型和Langmuir等温模型。此外，CISP在7次吸附–解吸循环后仍保持85%以上的去除率，并展现出对Ca²⁺/Mg²⁺干扰离子的耐受性。本研究为开发高效、可再生的重金属吸附材料提供了新思路。

Abstract: A dual-crosslinked chitosan-based hydrogel adsorbent (CISP) was synthesized via a synergistic strategy combining free radical polymerization and freeze-thaw cycling. The three-dimensional network structure was constructed through chemical crosslinking with N,N’-methylenebisacrylamide and physical entanglement with polyvinyl alcohol, while functional groups (-COO⁻, $-S{O}_3^{-}$ , -OH) were introduced via grafting of itaconic acid and sodium methacrylate sulfonate. The adsorption behaviors and mechanisms of CISP toward Cu²⁺ and Cd²⁺ were systematically investigated. FTIR and XPS analyses confirmed the coordination interactions between functional groups and metal ions. Under optimized conditions (pH 3~5, 25˚C, dosage 3 g/L), CISP exhibited removal efficiencies of 92.9% for Cu²⁺ and 91.2% for Cd²⁺. The adsorption process followed pseudo-second-order kinetics and Langmuir isotherm models. Remarkably, CISP maintained over 85% removal efficiency after 7 adsorption-desorption cycles and demonstrated tolerance to competitive ions (Ca²⁺/Mg²⁺). This work highlights the potential of CISP as a sustainable and regenerable adsorbent for heavy metal remediation.