多硫化钙与亚铁盐联用去除工业废水中的Cr(Ⅵ)

Removing hexavalent chromium from industrial wastewater by combined use of calcium polysulfide and ferrous sulfate

还原稳定化修复技术是当前重金属污染修复领域的主要技术,其中,重金属去除率和环境扰动是评价修复效果的重要指标。以不同pH重铬酸钾溶液模拟Cr(Ⅵ)污染水体,分别研究了多硫化钙、硫酸亚铁和二者联用对水体重金属Cr(Ⅵ)的还原稳定性,同时考察了环境因素对药剂联用的影响并探究各药剂对Cr(Ⅵ)的去除机理。结果表明:当多硫化钙与硫酸亚铁投加比例为1∶2时,药剂联用对Cr(Ⅵ)和总Cr的去除效果均优于单独施加药剂时的去除效果且还原产物较稳定,对体系扰动作用相对较小;低pH和较高温度有利于联用药剂对Cr(Ⅵ)的去除,HCO_(3)^(−)、Cl^(−)、Mn^(2+)的加入有利于去除Cr(Ⅵ),Fe^(3+)对Cr(Ⅵ)去除表现为低浓度抑制、高浓度促进;经反应产物成分分析,多硫化钙与硫酸亚铁反应生成了具有催化效果的FeS,提高了修复效果。以上研究结果可为后期Cr(Ⅵ)污染水体的控制和修复提供参考。

Reduction and stabilization remediation is a type of main technology in the field of heavy metal pollution remediation.Heavy metal removal rate and environmental disturbance are the important indicators to evaluate remediation effect.In this study,potassium dichromate solution with different pH was used to simulate Cr(Ⅵ)polluted water body,and the reduction stability of heavy metal Cr(Ⅵ)in water body was investigated by calcium polysulfide,ferrous sulfate and their combination,respectively,as well as the effects of environmental factors on the combination and Cr(Ⅵ)removal mechanisms by these chemicals.The results show that when the dosage ratio of calcium polysulfide and ferrous sulfate was 1∶2,the removal effect of Cr(Ⅵ)and total Cr by these two chemicals combination was better than that by single chemical,then more stable reduction products and lower environmental disturbance occurred.When calcium polysulfide and ferrous sulfate were used alone to remove Cr(Ⅵ)in polluted water body,low pH value,relatively high temperature and the addition of HCO_(3)^(−)、Cl^(−)、Mn^(2+) were conducive to Cr(Ⅵ)removal by these chemicals combination,while Fe^(3+) had an inhibitory effect at low content and a promotion effect at high content.The component analysis of reaction product shows that calcium polysulfide reacted with ferrous sulfate to form FeS with catalytic effect,which could improve the repair effect.The results can provide theoretical basis for the control and restoration of Cr(Ⅵ)polluted water body afterwards.