针对单一还原法和固化/稳定化技术处理铬污染土效果不佳的问题,提出还原-固化/稳定化联用方法,通过单掺试验和L9(34)正交试验,确定了还原剂、吸附剂、固化剂所组成的复合制剂的最佳配比,并采用扫描电镜对固化/稳定化铬污染土进行了微观表征。研究结果表明,复合制剂最佳配比为:CaS5用量是污染土中Cr(VI)还原为Cr(Ⅲ)所需理论还原剂量的3倍;合成沸石掺量为15%;水泥掺量为20%。扫描电镜分析结果显示,复合制剂通过还原-吸附-固化联合作用,减小了Cr(VI)和Cr(Ⅲ)对水化反应和凝硬反应的阻碍作用,强化了固化/稳定化效果,对固化体的浸出浓度降低效果显著,毒性浸出满足相关标准要求。
Abstract
Single reduction method and solidification/stabilization technology are inefficient in dealing with chromium polluted soil. A method combining pollution reduction and soil solidification/stabilization is presented in this paper. The optimum mix proportion of the compound treating agent composing reducing agent, adsorbent and curing agent was determined through single-doping test and L9(34) orthogonal test. The solidified/stabilized chromium contaminated soil was microscopically characterized by scanning electron microscopy. Results show that the optimum mix proportion of the compound is: the dosage of calcium polysulfide is three times the theoretical reducing dosage required to reduce Cr(VI) in the contaminated soil to Cr(Ⅲ) , synthetic zeolite content is 15%, and cement content is 20%. SEM analysis demonstrates that the compound alleviates the blocking effect of Cr(VI) and Cr(Ⅲ) on hydration reaction and coagulation reaction through the combined actions of reduction, adsorption, and solidification, and strengthens the curing/stabilizing effect. It also has evident effect of reducing the leaching concentration of the cured body, with the toxic leaching result meeting standard requirements.
关键词
铬污染土 /
CaS5 /
粉煤灰合成沸石 /
水泥 /
正交试验 /
微面特性
Key words
chromium contaminated soil /
CaS5 /
zeolite synthesized from coal fly ash /
cement /
orthogonal test /
micro-characteristics
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基金
国家重点研发计划重点专项(2017YFC1503106);辽宁省自然科学基金指导计划项目(2019-ZD-0037);辽宁省百千万人才工程项目(2018C01)
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