Abstract

This study investigates the adsorption of Ni(II) and Cd(II) ions from single and binary metal ion solutions onto chitosan and crosslinked chitosan beads, which was accomplished by an environmentally-friendly crosslinker, sodium tripolyphosphate. The synthesized adsorbents were characterized by swelling test, BET and SEM, and tested for Ni(II) and Cd(II) uptake after optimizing experimental factors, including adsorbent concentration (0.55 g/L) and initial pH (6.5). The single-ion equilibrium adsorption data fitted well by the Langmuir model. In the binary system, a decrease in adsorption capacity was observed, implying the existence of preference in the order of Ni(II) > Cd(II). Among the studied models for competitive adsorption, the extended Freundlich model fitted successfully for the adsorption equilibrium data. Characterization of loaded crosslinked chitosan beads showed amino and phosphate groups were responsible simultaneously for the metal ions uptake. Desorption experiments were also conducted by using a mixture of NaCl and H₂SO_4, showing acceptable results.

摘要

本研究研究了 Ni(II) 和 Cd(II) 离子从单一和二元金属离子溶液中吸附到壳聚糖和交联壳聚糖珠上，这是通过环保交联剂三聚磷酸钠完成的。通过溶胀试验、BET 和 SEM 对合成的吸附剂进行了表征, 并在优化吸附剂浓度 (0.55 g/L) 和初始 pH (6.5) 等实验因素后测试了 Ni(II) 和 Cd(II) 的吸收。Langmuir模型很好地拟合了单离子平衡吸附数据。在二元系统中，观察到吸附容量降低，这意味着存在优先顺序为 Ni(II) > Cd(II)。在所研究的竞争吸附模型中，扩展的 Freundlich 模型成功地拟合了吸附平衡数据。负载的交联壳聚糖珠的表征表明氨基和磷酸基团同时负责金属离子的吸收。还通过使用 NaCl 和 H 的混合物进行解吸实验₂ SO _4，显示可接受的结果。