【摘要】 采用多硫化钙(CaS5)对铬污染土进行稳定化处理,基于浸出试验、碱性消解试验和形态提取试验,研究CaS5添加量和养护龄期对污染土中铬赋存形态及浸出特性的影响规律。结果表明:随着CaS5添加量和养护龄期的增加,Cr(VI)和总Cr的浸出浓度降低,稳定土中Cr(VI)的含量降低,当CaS5/Cr(VI)的摩尔比为2时,Cr(VI)和总Cr的浸出浓度均低于我国危险废弃物鉴别标准(GB/T50853-2007);当CaS5/Cr(VI)摩尔比为3时,7 d龄期稳定土中Cr(VI)的含量低于我国土壤环境质量标准(GB15618-2008)中工业和商业用地的限值(30 mg/kg);CaS5可使稳定土在较长龄期内保持良好的还原性。形态提取试验结果表明:CaS5添加量和养护龄期均会明显改变稳定土中铬的赋存形态,随着CaS5添加量的增加,弱酸提取态的铬向可还原态、可氧化态转化;养护龄期的增加可促使铬从可还原态向可氧化态转化。铬形态分布的改变是铬污染土稳定性能变化根本原因。更多还原

【Abstract】 Calcium polysulfide(CaS5) was used to stabilize chromium-contaminated soils.Leaching test,alkaline digestion test and sequential extractions test were conducted to investigate the influence of CaS5 dosage and curing time on stabilization properties and chromium speciation of chromium-contaminated soils treated by CaS5.Results showed that the leaching concentration(hexavalent chromium and total chromium) and hexavalent chromium content of the soil were decreased significantly with the increased CaS5 dosage and curing time.Leaching concentration(hexavalent chromium and total chromium) were all met the China regulatory limit(GB/T50853–2007),when CaS5/Cr(VI) molar ratio was 3.With CaS5/Cr(VI) molar ratio of 5,the amount of Cr(VI) in the soil met the China Environmental Regulation for industrial reuse[Cr(VI)<30 mg/kg].Sequential extractions test showed that majority of acid soluble fraction of chromium was converted to reducible fraction and oxidisable fraction with CaS5 stabilized.With curing time increased reducible fraction of chromium was converted to oxidisable fraction.The changing in stabilize properties of stabilized soil can be attributed to the change of chromium speciation.更多还原