沸石在环境保护中的新应用

NEW APPLICATIONS OF ZEOLITES FOR ENVIRONMENT PROTECTION

本文综述了沸石在控制环境中亚硝胺污染、净化处理废水以及沸石在农业生产和其他环境保护领域中应用的新进展。沸石是香烟添加剂的首选材料,能使侧流烟气中的亚硝胺减少一半,主流烟气中减少约７０%,减轻吸烟者和被动吸烟者的污染危害。沸石的净化作用源于其对亚硝胺特殊的催化和吸附作用。香烟燃烧所产生的亚硝胺如果在高温下接触沸石,将被催化裂解;如果亚硝胺在较低温度下接触沸石,也会被沸石吸附而不再污染环境。沸石的特殊吸附功能使之成为缓释肥料的重要组成部分。沸石和高分子材料组装、分散之后,能制成调控植物根苗附近小环境水含量的功能性复合材料。

Progresses in the applications of zeolites on environment protection are reviewed, especially on the removal of N-nitrosamines from the cigarette smoke and beer, purification of waste water and novel compound fertilizer as well as water-retaining materials in soils.It is shown that strong interaction exists between zeolites and N-nitrosamines and the TPSR spectra of NDMA on Nay,NaZSM-5 and HZSM-5 zeolites as well as NPYP on zeolites and molecular sieves is seen in Figs. 2 and 3. Addition of zeolite in cigarette could remove N-nitrosamines of 60% to 70% from the main-smoke, while around 40% to 50% from the side-smoke without any change in the taste of the cigarette. Since the dispersed zeolite forms an especial in situ catalysis and/or absorption layer on tobacco, pollution of N-nitrosamines in the smoke is thus suppressed, because the N-nitrosamines should contact with the zeolite layer. When N-nitrosamines contacts the zeolite at high temperature, they can be catalytically decomposed. If N-nitrosamines contacts the zeolite at a relatively low temperature, they will be strongly absorbed in the zeolite without escaping. As a result, the health of both smokers and non-smokers is protected at the same time, which will be a novel way to exclude the pollution of cigarette smoke.There are other applications of zeolites and these are reviewed in the paesent paper. First,the special absorption function of zeolite make it become an important component in the novel fertilizer. Second,after mixed with polymer materials, zeolite could be used as functional material for keeping the moisture of soil. The variation of the moisture of soil before and after the addition of zeolites (5 wt. %) with time for different zeolites is illustrated and is seen in Figs. 4-6.