University of Reading.
Sci Prog. 2010;93(Pt 3):223-84. doi: 10.3184/003685010X12800828155007.
Zeolites are aluminosilicate solids bearing a negatively charged honeycomb framework of micropores into which molecules may be adsorbed for environmental decontamination, and to catalyse chemical reactions. They are central to green-chemistry since the necessity for organic solvents is minimised. Proton-exchanged (H) zeolites are extensively employed in the petrochemical industry for cracking crude oil fractions into fuels and chemical feedstocks for other industrial processes. Due to their ability to perform cation-exchange, in which the cations that are originally present to counterbalance the framework negative charge may be exchanged out of the zeolite by cations present in aqueous solution, zeolites are useful as industrial water-softeners, in the removal of radioactive Cs+ and Sr2+ cations from liquid nuclear waste and in the removal of toxic heavy metal cations from groundwaters and run-off waters. Surfactant-modified zeolites (SMZ) find particular application in the co-removal of both toxic anions and organic pollutants. Toxic anions such as arsenite, arsenate, chromate, cyanide and radioactive iodide can also be removed by adsorption into zeolites that have been previously loaded with co-precipitating metal cations such as Ag+ and Pb2+ which form practically insoluble complexes that are contained within the zeolite matrix.
沸石是一种带负电的硅铝酸盐固体，具有微孔的蜂窝状骨架，分子可以被吸附在其中，用于环境净化和催化化学反应。由于有机溶剂的必要性最小化，它们是绿色化学的核心。质子交换（H）沸石在石油化工行业中广泛用于将原油馏分裂化成燃料和其他工业过程的化学原料。由于它们能够进行阳离子交换，即原本存在于沸石中来平衡骨架负电荷的阳离子可以被水溶液中的阳离子交换出来，因此沸石可用作工业水软化剂，用于从液态核废料中去除放射性 Cs+和 Sr2+阳离子，以及从地下水和径流水中去除有毒重金属阳离子。表面活性剂修饰沸石（SMZ）在同时去除有毒阴离子和有机污染物方面具有特殊的应用。沸石也可以通过吸附预先负载有共沉淀金属阳离子（如 Ag+和 Pb2+）的沸石来去除有毒阴离子，如亚砷酸盐、砷酸盐、铬酸盐、氰化物和放射性碘化物，这些金属阳离子形成几乎不溶的复合物，包含在沸石基质中。
