壳聚糖-Fe(Ⅲ)复合凝胶球去除磷酸根的影响因素与吸附机理

Main Influencing Factors and Removal Mechanism of Phosphate Anions by Chitosan-Fe(Ⅲ)Composite Gel Beads

为改善当前环境水体中的磷污染现状,利用溶胶-滴定-真空冷冻干燥法制备了壳聚糖-铁(CS-Fe)复合凝胶球去除水中磷酸根。对CS-Fe凝胶球的形貌结构进行了表征,研究了材料对磷酸根的吸附影响因素,并探索了反应机理。结果表明,CS-Fe对磷酸根的吸附为自发、吸热、熵增过程;吸附过程符合拟一级动力学方程,吸附平衡时间为50 min;根据Langmuir模型计算最大吸附量为23.97 mg/g,脱附效率大于90%。傅里叶红外光谱(FT-IR)、扫描电子显微镜-能量散射谱(SEM-EDS)、Zeta电势分析、X射线光电子能谱(XPS)等证明,CS-Fe形成利于磷酸根快速吸附的蜂窝状结构;吸附机理包含静电吸附和离子交换过程。该吸附剂将金属化合物的吸附性能与壳聚糖大分子利于构建多孔材料的特点相结合,改善了吸附效果,球状材料更利于回收,避免二次污染,具有良好应用前景。

In order to improve the present situation of phosphorus pollution in environmental water,the chitosan iron(CS-Fe)composite gel beads were prepared by sol-titration-vacuum freeze drying method to remove phosphate from water.The morphology and structure of CS-Fe gel beads were characterized,and the factors affecting the adsorption of phosphate and the reaction mechanism were explored.The results show that the adsorption of phosphate by CS-Fe is a spontaneous,endothermic and entropy-increasing process,the adsorption process is in accordance with the pseudo first-order kinetic equation,the adsorption equilibrium time is 50 min,the maximum adsorption capacity calculated by Langmuir model is 23.97 mg/g,and the desorption efficiency is more than 90%.Fourier transform infrared(FT-IR),scanning electron microscopy-energy dispersive spectroscopy(SEM-EDS),Zeta potential analysis and X-ray photoelectron spectroscopy show that CS-Fe forms a honeycomb structure which is favorable for the rapid adsorption of phosphate,and the adsorption mechanism includes electrostatic adsorption and ion exchange.The adsorbent combines the adsorption properties of metal compounds with the characteristics of chitosan macromolecule,which is conducive to the construction of porous materials and improvement of the adsorption effect.Gel beads materials are more conducive to recovery,avoid secondary pollution,and have potential applications.