铋法去除垃圾渗滤液氯离子及其产物高值化利用机制

Removal of chloride ions in landfill leachate by bismuth method and the high-value utilization mechanism of its chloride removal product

高浓度含氯有机废水在处理过程中不仅会消耗过多的化学药剂,还会产生大量的废弃产物.为实现废弃物氯离子和有机污染物的去除和高值利用,本文以垃圾渗滤液为研究对象,采用化学共沉淀与高温煅烧的方法制备了Er^(3+)和Yb^(3+)掺杂型上转换荧光粉.实验结果表明,当Bi_(2)O_(3)除氯剂和稀土投加量达到Bi^(3+)∶Cl−∶Yb^(3+)∶Er^(3+)物质的量比为1∶1∶0.2∶0.02时,渗滤液Cl−、COD和TOC的去除效率分别为52.7%、45.7%和36.6%.除氯产物在温度为600℃煅烧后,所得样品在980 nm激光激发下的上转换发光强度最高,发光光谱包括强烈的绿光和红光,绿光区域在523—553 nm和红光区域在655—670 nm.上转换荧光增强机制分析表明,相对于Bi_(2)O_(3)和BiOCl,基质材料Bi_(3)O_(4)Cl和Bi_(12)O_(17)C_(l2)为Er^(3+)和Yb^(3+)离子提供了更好的掺杂环境.因此,虽然除氯产物中还剩余Bi_(2)O_(3),但其可与BiOCl在高温煅烧下形成Bi_(3)O_(4)Cl和Bi12O17Cl2,为上转换发光强度的提高和光谱调节提供了便利,也为渗滤液中氯离子和有机污染物的去除和高值资源化利用提供了新的方法.

The treatment of highly concentrated chloride-containing organic wastewater not only consumes too many chemicals,but also produces a large number of wastes.To realize the removal and high-value utilization of the chloride(Cl-)ions and organic pollutants in wastes,in this work,the landfill leachate was used as the research object,and the Er^(3+)/Yb^(3+)doped upconversion phosphors were prepared by a chemical co-precipitation and high temperature calcination method.The experimental results showed that,when the added dosages of Bi_(2)O_(3)and lanthanides reached the Bi^(3+)∶Cl−∶Yb^(3+)∶Er^(3+)molar ratio of 1∶1∶0.2∶0.02,the removal efficiencies of Cl−,chemical oxygen demand(COD)and total organic carbon(TOC)in leachate were 52.7%,45.7%and 36.6%,respectively.When the terminal chloride removal precipitate was calcinated at the temperature of 600℃,the upconversion luminescence intensity of the obtained sample is the highest under 980 nm laser excitation.The luminescence spectrum contained strong green and red light,wherein the green light region was at 523—553 nm and the red light region was at 655—670 nm.The analysis of the enhancement mechanism of upconversion luminescence showed that the matrix agents of Bi_(3)O_(4)Cl and Bi_(12)O_(17)C_(l2) provided better doping environments for Er^(3+)and Yb^(3+)ions than those of Bi_(2)O_(3)and BiOCl.Therefore,although Bi_(2)O_(3)remains in the terminal chloride removal precipitate,it is able to react with BiOCl to form Bi_(3)O_(4)Cl and Bi12O17Cl2 under the high temperature calcination process,which not only facilitates the improvement of upconversion luminescence and spectral adjustment,but also provides a new method for the removal and high-value resource utilization of Cl−ions and organic pollutants in leachate.