聚丙烯腈改性及其对Hg^(2+)吸附研究

Modifi cation of Polyacrylonitrile and Its Adsorption of Hg^(2+)

Hg^(2+)是生态环境中存在的对人体健康危害最大的重金属离子之一。吸附法是一种去除Hg^(2+)最简单高效的方法。因此设计成本低廉、吸附性能好且能循环利用的吸附剂是非常重要的。采用乳液自由基聚合技术制备聚丙烯腈,然后用三乙烯四胺对聚丙烯腈进行改性,得到改性后的聚丙烯腈。以废水中Hg^(2+)为吸附对象,考察不同的实验条件下,改性后的聚丙烯腈对Hg^(2+)的吸附性能。在pH值为6,Hg^(2+)浓度为40 mg/L,即时吸附量q_(t)达到最大;吸附30 min后吸附基本达到饱和。分别用伪一级吸附和伪二级吸附方程动力学模型对实验数据进行拟合,结果表明,用伪二级动力学方程可以更好描述吸附过程,说明三乙烯四胺改性聚丙烯腈对Hg^(2+)的吸附过程受Hg^(2+)扩散和-NH_(2)与Hg^(2+)的配位反应影响,为化学吸附。

Hg^(2+)is one of the most harmful heavy metal ions to human health in the ecological environment.Adsorption is the simplest and most efficient method for removing Hg^(2+).Therefore,it is very important to design adsorbents that are low-cost,have good adsorption performance,and can be recycled.Polyacrylonitrile was prepared by radical polymerization in emulsion,and then modified by triethylenetetramine to obtain modified polyacrylonitrile.Hg^(2+)in wastewater was used as the adsorption object,the adsorption performance of modified polyacrylonitrile on Hg^(2+)was investigated under different experimental conditions.At a pH value of 6 and a Hg^(2+)concentration of 40 mg/L,the immediate adsorption capacity q_(t) reached its maximum;After 30 minutes of adsorption,the adsorption basically reached saturation.The experimental data were fitted using pseudo first order adsorption and pseudo second order adsorption equation kinetic models,respectively.The results showed that the pseudo second order kinetic equation could better describe the adsorption process,indicating that the adsorption process of triethylenetetramine modified polyacrylonitrile on Hg^(2+)was influenced by Hg^(2+)diffusion and the coordination reaction between-NH_(2) and Hg^(2+),indicating chemical adsorption.