不同因素对多硫化钙处理地下水中Cr（VI）效果影响

摘要

Effectiveness of chromium reduction by calcium polysulfide was the obiective of this paper. Factrors were investigated such as pH, CaS5 concentrations, temperature and Mn(II), Fe(III), HA-contained water. When the rato of CaS5 and Cr(VI) ranged from 1∶1 to 5∶1, the Cr(VI) reduction rate inceased from 41.03%to 100.00%;The pH value of the water environmemt differed from 6.0 to 9.0, the reduction rate of Cr(VI) was 27.16%;The balance time was shorten 4~6 times when temperature of the water environmemt rised from (7±1) ℃ to (27±1) ℃; As Mn(II) was the principal component of Cr(VI)-contained water, the higher Mn(II) concentration(0.00~10.00 mg·L-1), the faster reaction velocity between CaS5 and Cr(VI); The concentration of Fe(III) consisting in groundwater transfered from 0.00 mg·L-1 to 10.00 mg·L-1, the removal rate increased by 9.05%;When HA existed in the ground water(0.00~15.00 mg·L-1), the Cr(VI) reduction rate varied from 99.31%to 90.28%;The XRD showed the products of the reaction between calcium polysulfide and hexalvant chromium were Cr(OH)3 and S, whose 2θdegree corresponded to 18.2°, 19.36°, 26.67° and 23.02°. When calcium polysulfide treated 11.38 mg·L-1Cr(VI)-contami-nated ground water ,removal rate of Cr(VI) can reach 90.28%. Output concentration of Cr(VI) can reach to III class of Quality standard for groundwater GB/T 1448-93. Calcium polysulfide has been found a promising reductant in the treatment of Cr(VI)-contained groundwater.%选用多硫化钙为还原剂，进行地下水中Cr(VI)去除效果的研究。主要考察了多硫化钙投加量、溶液pH、温度、Mn(II)、Fe(III)、腐殖酸（HA）存在条件下，对多硫化钙处理Cr(VI)效果的影响。结果表明：当多硫化钙与Cr(VI)的摩尔比由1∶1变到5∶1时，去除率从41.03%增加到100.00%；溶液pH值从6.0增上升到9.0时，去除率下降27.16%；水环境温度由(7±1)℃增加到(27±1)℃时，去除率达到100.00%所需反应时间，缩短了4~6倍；当地下水中含有Mn(II)，随着Mn(II)质量浓度升高（0.00~10.00 mg·L-1），Cr(VI)浓度低于检测线所需要的时间缩短3倍；当地下水中含有Fe(III)，Fe(III)质量浓度从0.00 mg·L-1增加到10.00 mg·L-1，去除率增加9.05%；当地下水中含有HA(0.00~15.00 mg·L-1)，去除率由99.31%降低至90.28%。（7）多硫化钙与六价铬的反应产物的X射线衍射光谱图像中2θ值为18.2°、19.36°、26.67°与Cr(OH)3，2θ值为23.02°与单质S的标准卡片匹配度较高。另外，对含有11.36 mg·L-1 Cr(VI)实际污染地下水的处理效果表明，Cr(VI)的去除率达到99.78%，残留浓度达到GB/T 1448—1993地下水质量标准III类标准，说明多硫化钙修复实际铬污染地下水具有良好的应用前景。