层状金属有机框架材料用于水溶液中137Cs的高效去除

Layered Metal Organic Framework for Effective Removal of 137Cs from Aqueous Solution

137Cs主要来源于核武器试验和核电站产生的放射性废物,具有高溶解度和高迁移率的特点,因此从放射性废液中有效去除137Cs是一项长期的挑战。本研究通过溶剂热法合成了一种二维层状阴离子骨架材料SZ-6,并对其吸附性能进行了系统的研究。利用单晶衍射仪、X射线衍射仪和扫描电子显微镜等对SZ-6的结构、形貌和稳定性进行了表征与测试。采用批实验研究了水溶液中Cs+的吸附行为。结果表明:在浓度为10 mg/L的Cs+溶液中,SZ-6的吸附动力学可在5 min内达到平衡,是目前去除Cs+最快的吸附剂材料之一;SZ-6在pH4~12范围内表现出良好的去除能力;在过量Na+、K+、Ca2+竞争阳离子存在的情况下仍具有较好的选择性。

137Cs is one of the most intractableβ-emitters which is commonly generated from nuclear weapons test and nuclear power station.Due to the nature of high solubility and mobility,the effective sequestration of 137Cs+from radioactive waste solution is considered as a long-term challenge.In this work,a two-dimensional layered anion framework material(SZ-6)was synthesized through conventional solvothermal reaction and the Cs+removal properties were systematically investigated.Single Crystal X-ray Diffraction(SCXRD)analysis revealed that SZ-6 adopts layer packed structure with large tetramethylammonium cations loaded between the layers which is greatly beneficial to cation exchange process.Powder X-ray Diffraction(XRD)and Scanning Electron Microscope(SEM)confirmed the material with high purity and excellent hydrolytic stability.Batch experiments were used to investigate the adsorption behavior towards Cs+in aqueous solutions.The adsorption kinetics of SZ-6 could be achieved within 5 min,which is currently one of the fastest sorbents for the removal of Cs+.Meanwhile,SZ-6 exhibits superior decontamination capability over a wide pH range from 4 to 12.Furthermore,it possesses marked selectivity in the presence of large excess of Na+,K+,Ca2+competing cations.