地下水化学类型对硫系还原剂去除Cr(Ⅵ)的影响  

Effects of groundwater chemistry on chromium(Ⅵ) removal by sulfur-based reducing agents

作　　者：朱帅[1] 张旭[1] 李广贺[1] ZHU Shuai ZHANG Xu LI Guanghe(School of Environment, Tsinghua University, Beijing 100084, China)

机构地区：[1]清华大学环境学院,北京100084

出　　处：《环境工程学报》2016年第11期6205-6211,共7页Chinese Journal of Environmental Engineering

基　　金：国家高技术研究发展计划(863计划)项目(2013AA06A207)

摘　　要：为研究铬污染地下水化学类型对硫系还原剂除铬的影响,采用批实验的方式,分别比较了3种还原剂焦亚硫酸钠(Na_2S_2O_5)、连二亚硫酸钠(Na_2S_2O_4)、多硫化钙(Ca Sx)对SO_4-Na型、SO_4-Ca型、Cl-Na型和HCO_3-Ca型4种地下水中去除Cr(VI)的效果。结果表明,在20℃有氧条件下,4种地下水环境中还原剂的除铬能力受到了不同程度的抑制,其中HCO_3-Ca型地下水中的抑制作用最大。但当Na_2S_2O_5、Na_2S_2O_4、Ca Sx投加量分别为理论投加量的30.8、21.7和2.4倍时,4种地下水中Cr(VI)的去除率均大于90%。Na_2S_2O_5投加量与水中HCO-3含量的摩尔比大于0.5时,Cr(VI)才可能被还原去除;Na_2S_2O_4对Cr(VI)的去除率由高到低排序是:SO_4-Na型>Cl-Na型>SO4-Ca型>HCO_3-Ca型;Ca Sx的除铬效果在不同地下水化学类型中的差异最小。地下水的HCO-3含量越高,缓冲能力越强,抑制作用越明显,所需还原剂投加量越多。To study the effects of groundwater chemistry on chromium（ VI） removal by sulfur-based reducing agents in chromium-contaminated sites,the effectiveness of three reducing agents（ sodium metabisulfite（ Na_2S_2O_5）,sodium dithionite（ Na_2S_2O_4）,and calcium polysulfide（ Ca Sx）） was evaluated in four types of artificial groundwater（ SO_4-Na,SO_4-Ca,Cl-Na,and HCO3-Ca）. The results of batch experiments showed that the reduction of Cr（ VI） in different types of groundwater was inhibited to various extents under aerobic conditions,with HCO3-Ca showing the most significant inhibition. Cr（ VI） removal was 90% when the dosages of Na_2S_2O_5,Na_2S_2O_4,and Ca Sxwere 30. 8 times,21. 7 times,and 2. 4 times that of the theoretical dosage,respectively,for all types of groundwater. Using Na_2S_2O_5 as the reducing agent,the reduction of Cr（ VI） occurred only when the dosage was more than half the molar concentration of HCO-3in groundwater. The removal of Cr（ VI） by Na_2S_2O_4 in groundwater followed the order： SO_4-Na Cl-Na SO_4-Ca HCO_3-Ca. The groundwater chemistry had the least impact on the reductive capacity of Ca Sx. With increasing HCO_3^-concentration,the buffer capacity of groundwater increased,and greater amounts of reducing agents were required due to the greater inhibition effect.

关 键 词：地下水化学 六价铬(Cr(Ⅵ)) 焦亚硫酸钠(Na2S2O5) 连二亚硫酸钠(Na2S2O4) 多硫化钙(CaSx) 

分 类 号：X523[环境科学与工程—环境工程]