制备斜发沸石和零价铁复合材料处理水中的六价铬污染

为了更好地降低我国地下水中六价铬污染给公众的健康带来的危害,本研究以渗透反应墙为处理地下水六价铬污染的主要方法,沸石和零价铁为反应材料,结合沸石虽价格低廉,但经长时间运行后吸附的六价铬有可能发生解吸,零价铁虽能完全去除六价铬但成本很高的特点,研发出了斜发沸石和零价铁的复合材料,以作为渗透反应墙的填充材料.研发主要分三个步骤:1)遴选出吸附效果较好的斜发沸石;2)确定最优表面活性剂及最优施用浓度;3)确定沸石与零价铁的复合工艺方法.最终方案为斜发沸石、六烷基三甲基溴化铵、还原铁粉、斜发沸石粉和超纯水按比例均匀混合后加热至90℃.由此制得的复合材料,具有良好的反应性能和便于装填的形状,生产成本也比较低廉,可以作为修复六价铬污染的反应墙填充材料.

Preparation of zeolite and zero valent iron composite for cleanup of hexavalent contamination in water

This study attempts to find better ways to remediate chromium contamination in groundwater and the associated public health hazard. Permeable reactive barrier (PRB) is the most widely used technology to remediate groundwater contaminated with hexavalent chromium. Zero valent iron and zeolite are the two reactive materials most commonly used in PRBs. Zero valent iron reduces hexavalent chromium into trivalent chromium but the cost to deploy zeron valent iron PRB is high. The cost of zeolite is relative low. However, hexavalent adsorbed by zeolite may be desorbed after long time operation. The objective of this study was to develop a composite material that combines both zero valent iron and zeolite to avoid the disadvantages of the two materials. The study involved three steps: 1) to select a zeolite with the best sorption efficiency; 2) to determine the optimal concentration of the surfactant to modify zeolite; 3) to identify the optimal process to prepare a composite material using zeolite and zero valent iron. Mixing clinoptilolite, CTAB-Br, zero-valent iron, clinoptilolite powder and ultrapure water at certain proportion and then heating the mixture to 90℃ was found to be the optimal procedure. The resultant composite material had the advantages of high reactivity, easy to pack, and low cost. Thus, it was suitable for PRB application to remediate groundwater contaminated with hexavalent chromium.