掺杂CoFe_(2)O_(4)膨胀石墨对Pb(Ⅱ)的吸附性能

Adsorption Behavior for Pb(Ⅱ)of Expanded Graphite Doped with CoFe_(2)O_(4)

为解决膨胀石墨吸附后回收难的问题,采用柠檬酸基的溶胶-凝胶法将CoFe_(2)O_(4)粒子负载到膨胀石墨中,制备磁性膨胀石墨。利用扫描电子显微镜(SEM)和磁滞回线对样品的微观形貌和磁性能进行表征,研究了膨胀石墨和磁性膨胀石墨对Pb(Ⅱ)吸附性能的影响因素,包括吸附时间、Pb(Ⅱ)初始质量浓度、吸附剂用量和pH值等,并采用吸附动力学和吸附等温线模型对吸附行为及机理进行了分析。结果表明,膨胀石墨和磁性膨胀石墨对Pb(Ⅱ)的最大吸附量分别为95.6、69.8 mg/g,吸附动力学符合二级动力学模型,吸附等温线符合Langmuir模型。掺杂CoFe_(2)O_(4)粒子缩短了膨胀石墨对Pb(Ⅱ)吸附平衡所需的时间,并使最佳吸附pH值向更加中性条件迁移。

In order to solve the problem of difficult recovery after adsorption of expanded graphite,magnetic expanded graphite was prepared by incorporating CoFe_(2)O_(4)particles into expanded graphite using the citric acid based sol-gel technique.The microcosmic performance and magnetic property of the products were characterized by SEM and hysteresis loop.The effect factors of the adsorption behavior for Pb(Ⅱ)of expanded graphite and magnetic expanded graphite were investigated,including adsorption time,initial concentration of Pb(Ⅱ),adsorbent dosage and pH value,as well as the adsorption behavior and mechanism were analysed using adsorption kinetics and adsorption isotherm model.The results show that the maximum adsorption capacities for Pb(Ⅱ)of expanded graphite and magnetic expanded graphite reach to 95.6 and 69.8 mg/g,respectively.The adsorption kinetics for Pb(Ⅱ)of expanded graphite and magnetic expanded graphite adhere to the pseudo-second-order kinetic model and the adsorption isotherms are well consistent with the Langmuir isotherm model.Incorporating CoFe_(2)O_(4)particles on expanded graphite shortens the time to obtain adsorption equilibrium condition for Pb(Ⅱ),and shifts the pH value of optimal adsorption to a more basic condition.