重金属捕集剂对水中微量Hg(Ⅱ)的处理研究

Research on Low-level Hg(Ⅱ) Removal from Water by the Heavy Metal Capturing Agent

针对含汞废水采用常规处理难以达标的问题,选用二硫代氨基甲酸盐类(DTCR-2)、2,4,6-三硫醇基钠硫代三嗪(TMT-18B)、硫化钠(Na2S)和氢氧化钙[Ca(OH)2]作为重金属捕集剂,对水中微量Hg2+进行深度处理研究.通过处理效果的对比,最终选用DTCR-2作为Hg2+最理想的捕集剂,重点考察了pH值、DTCR-2投加量、反应时间、Hg2+初始浓度及其他重金属离子等因素对Hg2+去除效果的影响.结果表明,在Hg2+初始浓度为100μg.L-1,pH为8.0,投加量1.0倍化学计量比,反应时间10 min时处理效果较好,Hg2+剩余浓度为41.36μg.L-1,低于国家排放标准中的限值(50μg.L-1).另外,Cd2+、Pb2+、Cu2+这3种重金属离子对DTCR-2去除Hg2+具有抑制作用,影响大小依次为Cu2+>Pb2+>Cd2+,而Zn2+具有促进作用.通过本研究,可以为DTCR-2处理低浓度含汞废水工艺设计提供理论支持.

Treatment of mercury containing wastewater using conventional approach is considered to be difficult to bring down its concentration to meet the discharge standard.In this study,we utilized dithiocarbamate（DTCR-2）,2,4,6-trimercaptotriazine（TMT18B）,Na2S and Ca（OH） 2 as the advanced treatment agents to remove low-level Hg2 ＋ from water.Due to its better treatment effect,DTCR-2 was finally chosen as the most ideal option.The influence of pH value,dosage of DTCR-2,reaction time,initial Hg2 ＋ concentration as well as other heavy metal ions on the Hg2 ＋ removal were studied.The results showed that DTCR-2 had high removal efficiency under the following conditions： 100 μg.L-1 of initial Hg2 ＋concentration,pH 8.0,1.0 times stoichiometric ratio of DTCR-2 dosage and 10 min of reaction time,leading to 41.36 μg.L-1 of residual Hg2 ＋concentration which was below the national discharge standard（50 μg.L-1）.Moreover,three heavy metal ions including Cd2 ＋,Pb2 ＋ and Cu2 ＋,inhibited the DTCR-2 capturing capacity towards Hg2 ＋ and the inhibition effects followed this order： Cu2 ＋ Pb2 ＋ Cd2 ＋,while Zn2 ＋ promoted the Hg2 ＋ removal.From this study,we could provide theoretical support for process design to deal with wastewater containing low mercury concentration using DTCR-2.