Mg/Fe类水滑石的磷酸根吸附性能及吸附机理

Phosphate adsorption performance and adsorption mechanism of Mg/Fe hydrotalcite-like

采用共沉淀法成功制备了Mg/Fe类水滑石(Mg/Fe-hlc),并研究了其对废水中磷酸根的吸附性能及吸附机理。研究结果表明:制备的Mg/Fe-hlc具有典型的类水滑石结构和较大的比表面积(156.7 m^2·g^-1);Mg/Fe-hlc对磷酸根的吸附动力学过程符合准二级动力学模型;Langmuir和Tempkin方程都可以很好地拟合Mg/Fe-hlc对磷酸根的等温吸附数据,Langmuir方程拟合得到的最大吸附量可达47.38 mg·g^-1;共存阴离子NO3^-、Cl^-和SO4^2-对磷吸附性能的影响很小;通过分析吸附磷酸根前后的Mg/Fe-hlc的结构和织构性质以及表面官能团变化,并结合溶液pH对磷酸根吸附影响实验结果,发现静电相互作用、配体交换和阴离子交换是Mg/Fe-htl吸附磷酸根的三种主要机制。

Mg/Fe hydrotalcite-like(Mg/Fe-hlc)was successfully prepared by co-precipitation method.The adsorption performance and adsorption mechanism of Mg/Fe-hlc on phosphate in wastewater were also studied.The results showed that the obtained Mg/Fe-hlc possessed the typical hydrotalcite-like structure and a large specific surface area of 156.7 m^2·g^-1.The phosphate adsorption kinetics of Mg/Fe-hlc accorded with the quasi-second-order kinetic model.Both Langmuir and Tempkin models fitted well with the isothermal adsorption data of phosphate on Mg/Fe-hlc,and the maximum adsorption capacity from Langmuir equation reached 47.38 mg·g^-1.The coexisting anions of NO3^-,Cl^- and SO4^2- hardly influenced the phosphate adsorption performance.The phosphate adsorption mechanism of Mg/Fe-hlc was investigated by analyzing the variation of structural and textural properties,surface functional groups of Mg/Fe-hlc before and after phosphate adsorption,as well as the effect of solution pH on the phosphate adsorption behavior.It was found that electrostatic interaction,ligands exchange and anion exchange were the three main mechanisms for phosphate adsorption on Mg/Fe-hlc.