柠檬酸功能化磁性Fe_(3)O_(4)微球的合成及其对铅和铬的吸附性能研究

Synthesis of Citric Acid Functionalized magnetic Fe_(3)O_(4) Microspheres and Research on Adsorption Performance for Lead and Cadmium

本文采用溶剂热法合成Fe_(3)O_(4)微球,通过接枝成功将柠檬酸修饰到Fe_(3)O_(4)微球表面,形成Fe_(3)O_(4)-CA。通过考察pH、金属离子初始浓度和吸附时间对吸附效率的影响,并对吸附等温线和吸附动力学进行拟合。研究表明,pH为7.0时,Fe_(3)O_(4)-CA对Pb^(2+)和Cr^(3+)的吸附效率最高,吸附动力学满足准二级速率模型,对铅离子(Pb^(2+))和铬离子(Cr^(3+))的最大吸附速率为16.01 g/h·mg和0.3588 g/h·mg,吸附等温线符合Langmuir模型,吸附能力为513.91 mg/g和397.72 mg/g。此外,Fe_(3)O_(4)-CA呈超顺磁性,饱和磁强度为37.5 emu·g^(-1),在外加磁场的条件下能快速从溶液中分离出来,且具有良好的循环稳定性,10次循环实验后其吸附性能仍能达到85%以上。

In this paper,Fe_(3)O_(4) microspheres were synthesized by solvothermal method,and citric acid was successfully grafted on the surface of Fe_(3)O_(4) microspheres to form Fe_(3)O_(4)-CA.The pH,initial concentration and adsorption time were investigated,in order to explore its influence on adsorption performance.The adsorption kinetics and adsorption isotherm model were fitted,the results show that the adsorption efficiency of Fe_(3)O_(4)-AC for Pb^(2+) and Cr^(3+) reaches maximum at pH 7.0.The adsorption kinetics fits the pseudo second order rate model,the maximum adsorption rates of Pb^(2+) and Cr^(3+) were 16.01 g/h·mg and 0.3588 g/h·mg,respectively.The adsorption isotherms conforms to the Langmuir model,and the maximum adsorption capacities were 513.91 mg/g and 397.72 mg/g.In addition,Fe_(3)O_(4)-CA is superparamagnetic with saturation magnetic strength of 37.5 emu·g^(-1).It can be separated from the solution quickly under the condition of external magnetic field.It has good cycle stability,adsorption performance can still reach more than 85% after ten cycles of adsorption and desorption.