氢氧化铁对水中砷的吸附作用研究

Study on Adsorption of Arsenic from Water on Iron Hydroxide

采用氢氧化铁做吸附剂,研究其对水体中As（Ⅲ）的吸附作用,探讨了pH、离子强度、干扰离子对As（Ⅲ）吸附的影响并对其吸附动力学进行了研究.结果表明：氢氧化铁能够在较宽的pH范围（pH为4.1～8.5）有效吸附As（Ⅲ）,其吸附等温线能够用Langmuir吸附模型很好地描述,最大静态吸附容量为9.09mg/g,吸附动力学符合Lagergren二级动力学方程;磷酸根、硅酸根、碳酸根等阴离子对As（Ⅲ）吸附有不同程度抑制作用,其余共存阴离子对As（Ⅲ）的吸附影响不大.同时对氢氧化铁吸附As（Ⅲ）的机理进行了探讨,得出氢氧化铁对As（Ⅲ）的吸附可能是静电非专性吸附及配位络合专性吸附共同作用的结果.

Ferric hydroxide is used as adsorbent to study its adsorption of As（Ⅲ） in this paper.The effect and adsorption kinetics of pH,ionic strength and interfering ions are also investigated.The results show that iron hydroxide can effectively adsorb As（Ⅲ） in a wide range of pH from 4.1 to 8.5.Meanwhile,the adsorption isotherm can be well described by the Langmuir adsorption model and the maximum static adsorption capacity is 9.09 mg/g.Adsorption kinetics fits Lagergren second order kinetics equation.Phosphate,silicate,carbonate and other anions inhibit As（Ⅲ） from being adsorbed in various degrees and other coexisting anions have a very little effective on As（Ⅲ） being adsorbed.At the same time,the mechanism of the adsorption of As（Ⅲ） by ferric hydroxide is discussed and the adsorption of As by iron hydroxide may be the result of the interaction between the electrostatic non-specific adsorption and specific adsorption complexation.