沸石分子筛在放射性废水处理领域的应用

Application of zeolite in the radioactive wastewater treatment

核工业是国家安全的重要基石,体现了国家的综合实力,是大国竞争的战略必争领域.核工业会产生放射性废水,用固态吸附质通过吸附/离子交换的方式可将放射性核素从液相转移到固相,从而实现核废水的减容,是有效处理核废水的方式之一.作为一种无机吸附剂,沸石分子筛凭借自身的优异理化性质和稳定性,在放射性废水处理中展现出较好的应用前景,得到越来越多的研究和关注.本文综述了国内外利用天然沸石、合成沸石和改性沸石去除废水中铯、锶、钴、铀、钚、镅、钐和铕等核素的研究进展,希望能为我国放射性废水处理技术的发展提供借鉴和参考;最后展望了未来的研究方向,以期推动沸石材料在工程技术领域的应用.

The nuclear industry is an important cornerstone of national security,reflects the comprehensive strength of a country,and is a strategic field for great powers to compete.However,a large amount of radioactive wastewater will be produced in the process of using nuclear energy,and radioactive ions such as60Co2+,137Cs+,90Sr2+,and99Tc O4-are the main sources of wastewater radioactivity.Radioactive ions are highly toxic and easy to migrate in water.Once they enter the ecosystem,they will have a significant impact on the environment.If they enter the human body,they will damage organs and tissues and even cause cancer.Therefore,it is of great significance to develop efficient,rapid,and economical radio-active wastewater treatment methods.There are many methods to treat radioactive wastewater,including extraction,chemical precipitation,membrane filtration,biological treatment,and adsorption.The use of solid adsorbents to transfer radionuclides from liquid phase to solid phase through adsorption/ion exchange,so as to realize the reduction of nuclear wastewater,is one of the effective ways to treat nuclear wastewater.Zeolite is a microporous crystal composed of a negatively charged aluminosilicate framework and free counter-cations in the pores.The cations in the pores can exchange ions with radionuclides from solution to achieve the adsorption of radionuclides.Because of its high ion exchange capacity,excellent hydrothermal,mechanical,and radiation stability,and low price,zeolite is an ideal material for treating nuclear wastewater.The research progress of natural zeolite,synthetic zeolite,and modified zeolite in the removal of cesium,strontium,cobalt,uranium,plutonium,americium,samarium,and europium from wastewater is reviewed.This review mainly expounds the difference of adsorption performance to nuclide of natural zeolite with different origin and different composition,and summarizes the application of natural zeolite in large-scale treatment of radioactive wastewater.The adsorption performance and mechanism of various synthetic zeolites,such as LTA,CHA,MOR,and HEU,on nuclides,especially on the adsorption performance of very low concentration radioisotopes,and the radiation resistance of zeolites were evaluated.In order to solve the problems of small particle size,difficult separation and poor stability of zeolite,new composite zeolite materials have attracted more and more attention.By combining zeolite with alginate,polyacrylonitrile,and magnetic metal,not only the absorption energy of zeolite is improved,but also the practicality of it is strengthened.The summary of the previous research results can provide reference for the development of radioactive wastewater treatment technology in China.At the same time,it also summarizes the problems existing in the previous research,such as the large difference between the composition of the experimental object and the real wastewater,the small number of total categories of the nuclides studied,the negative optimization of the adsorption performance of some composite materials,and the small number of simulation calculation studies.These problems need further in-depth study.Finally,the future research direction is discussed in order to promote future applications of zeolite materials in engineering technology.