飞灰螯合剂中挥发性污染物的释放

采集了4个市售飞灰螯合剂样品，分析其在20，40℃下挥发性污染物的释放规律.结果表明，释放的挥发性污染物主要有甲醛、乙醛、苯、异戊醛/异丙醇、甲硫醇、乙硫醇等；其中3个螯合剂样品甲醛的释放浓度在20℃为748~1325 μg/L-螯合剂，占释放的易挥发污染物的68%~96%（质量比），在40℃为4282~6822 μg/L-螯合剂，占释放的易挥发污染物的87%~95%（质量比）.随着温度升高，释放的挥发性污染物种类变多，部分污染物浓度增加，40℃时，4个螯合剂样品释放的易挥发污染物浓度比20℃时增加了142%~444%.元素分析、拉曼光谱和热重分析结果表明，4个螯合剂的主要有效成分相似，为二硫代氨基甲酸盐类物质.因此，推测这种飞灰螯合剂在稀释和飞灰稳定化过程中，对工作人员的健康可能有潜在的危害风险，应收集释放的气体并进行处理；且在飞灰填埋过程中，可能会导致渗滤液中NH₄⁺-N等物质的浓度升高，增加渗滤液的处理难度.

Release of volatile pollutants from four chelating agents used for stabilization of fly ash

Four commercially available chelating agents used for fly ash stabilization were collected and used to study the releasing characteristic of volatile pollutants at 20℃ and 40℃. The results showed that the released volatile pollutants were composed of formaldehyde, acetaldehyde, benzene, isovaleraldehyde/isopropanol, methyl mercaptan, ethyl mercaptan and so on. Among the volatile pollutants released from three chelating agent samples, the concentration of formaldehyde was the highest; at 20℃, the concentration of formaldehyde was 748~1325 μg/L-chelating agent, accounting for 68%~96%(mass ratio) of the released volatile pollutants; at 40℃, the concentration of formaldehyde was 4282~6822 μg/L-chelating agent, accounting for 87%~95% (mass ratio) of the released volatile pollutants. With the increase of temperature, more types of volatile pollutants were released from the chelating agents, and the concentrations of some pollutants increased. At 40℃, the concentrations of the volatile pollutants released from the four chelating agent samples increased by 142% to 444% compared with those at 20℃. Elemental analysis, Raman spectroscopy and thermogravimetric analysis showed that these four chelating agents had similar active ingredients of dithiocarbamates. It suggested that, during the storage, dilution, and fly ash stabilization processes, the pollutants released from this type of chelating agents might be harmful to the health of the operators. Emitted air pollutants should be collected for further treatment. In addition, during the fly ash landfill process, the residual chelating agents in the fly ash may increase the concentration of ammonia and other substances in the leachate, which would increase the difficulty for leachate treatment.