ZIF材料对碘的吸附特性研究

Adsorption of Iodine by ZIF Materials

核废水中的放射性碘对人类健康和环境有严重的危害,但是由于碘在水中以多种形式存在,很难准确测定其在水中的含量。开发能够准确测定水中碘单质含量的方法,制备有效去除碘单质的材料对保护环境和人类健康尤其重要。为此,本研究首先提出了用环己烷萃取法测定碘单质浓度的方法,并且制备了两种沸石咪唑骨架材料ZIF-8和ZIF-67,研究了ZIF-8和ZIF-67对水环境中碘的吸附行为。利用分析仪器对ZIF-8和ZIF-67材料进行了表征。结果表明:两种材料都具有良好的化学结构和较大的比表面积。吸附动力学实验结果表明,60 min内,两种材料对碘的吸附可以达到平衡,吸附行为更好地符合拟二级动力学模型。吸附热力学结果表明,两种材料在水中对碘的吸附过程均为线性吸附。ZIF-8和ZIF-67材料对碘单质的吸附量可高达2000 mg·g–1。

Radioactive iodine present in nuclear waste water streams is harmful to human health and environment.Since iodine will exist in multiple states in water,accurate quantification of the total iodine content in any given sample is very difficult.The development of a method for determining the total iodine content accurately in water,and finding materials which can effectively remove the iodine are of particular importance.Here,a method was proposed for determining the concentration of iodine by cyclohexane extraction.And two kinds of zeolite imidazole skeleton materials ZIF-8 and ZIF-67 were prepared to be used as adsorbents to effectively adsorb iodine from an aqueous environment.Samples ZIF-8 and ZIF-67 were characterized by different methods.The results show that these two kinds of materials have good chemical structure and large specific surface area.The results of adsorption kinetics experiments show that the adsorption of ZIF-8 and ZIF-67 materials to iodine can reach the equilibrium within 60 min.The iodine adsorption behaviors of both materials are fitted with the pseudo second-order kinetic model.Their adsorption thermodynamics indicate linear adsorption behavior for iodine in the case of both zeolites.Adsorption capacities of ZIF-8 and ZIF-67 for iodine could reach as high as 2000 mg·g?1.