新型高分子絮凝剂对水中有机配位汞的捕集性能

Performance of trapping mercury combined with organic coordination agent in water by novel macromolecule flocculant

将二硫代羧基引入到聚乙烯亚胺中,制备出一种新型高分子絮凝剂聚乙烯亚胺基黄原酸钠(PEX).以含汞水样为处理对象,考察了水样pH值对PEX去除Hg2+效果的影响,并研究了水样中存在有机配位剂EDTA、柠檬酸铵以及氨基乙酸等时,PEX捕集Hg2+的性能.实验结果表明,在不同pH值下,该絮凝剂对Hg2+均具有很好的捕集效果,Hg2+的最高去除率均可达到100%.pH值对PEX投加量有一定的影响,同样去除率下,pH值较低时,PEX投加量相对较多.水样中EDTA的存在,在一定程度上会抑制Hg2+的去除,但增加PEX投加量会减弱或消除此影响.柠檬酸铵的存在会促进Hg2+的去除;而氨基乙酸的存在,在较低pH值下会促进Hg2+的去除,pH值升高时其对Hg2+的去除表现为抑制作用.絮体浸出实验表明汞的浸出率较低,PEX—Hg絮体具有很好的稳定性,不易引起二次污染.

A novel macromolecule flocculant polyethyleneimine-sodium xanthogenate（PEX） was synthesized by grafting a dithiocarboxylic group onto polyethyleneimine.The effect of pH values on the removal efficiency of mercury was investigated for the mercury-containing water sample.The performance of PEX trapping mercury was also studied for the water samples containing both mercury and some organic coordination agents,such as EDTA salt,ammonium citrate and aminoacetic acid.The experimental data show that the PEX had the strong binding capability with Hg2＋ at all of pH values studied,and the removal rate nearly reaches 100% for some pH values.More dosage of PEX was needed at low pH values to reach the high removal efficiency obtained at high pH values.The coexistence of EDTA salt in water sample could affect the removal of Hg2＋ to a certain extent,but this effect would be reduced or eliminated by the increased dosage of PEX.The coexistence of ammonium citrate in water sample could promote the removal of Hg2＋.As far as the coexistence of aminoacetic acid was concerned,it could promote the removal of Hg2＋ at low pH values,but depress the removal of Hg2＋ with the increase in pH values.The lower Hg extraction rate obtained in the leaching experiment indicated that the flocs of PEX—Hg had the very good stability,and therefore it would not be easy to cause secondary pollution by the sludge produced in this treatment.