Shanghai Academy of Environmental Sciences, Shanghai 200233, PR China.
Shanghai Academy of Environmental Sciences, Shanghai 200233, PR China.
J Hazard Mater. 2017 Jan 5;321:73-80. doi: 10.1016/j.jhazmat.2016.09.003. Epub 2016 Sep 4.
The potential risk of heavy metal in soil can be reduced by stabilization techniques. Stabilizing amendments, montmorillonites modified with tetramethylammonium (TMA) and hexadecyltrimethylammonium (HDTMA) at different loadings were prepared, characterized and assayed for remediation of hexavalent chromium contaminated soil. Characterization results demonstrated that TMA modification resulted in increased surface area and pore volume, whereas HDTMA modification resulted in decreased surface area and pore volume. For HDTMA modified montmorillonites (H-Monts), the arrangement model of surfactant molecules and the structural characteristics strongly depended on the surfactant loading density. Less pronounced packing density dependence was observed for TMA modified montmorillonites (T-Monts). Modified toxicity characteristic leaching procedure (TCLP) was utilized to evaluate the chromium immobilizing capacity of the prepared organo-montmorillonites, and the results revealed that both T-Monts and H-Monts can be reasonably effective in chromium stabilization under different leaching condition. The comparison of chromium leaching behavior manifested by T-Monts and H-Monts suggested that mechanisms for chromium immobilization by organo-montmorillonites amendment proceeded via two adsorption approaches. Each approach involves different functional groups, depending on the leaching pH and surfactant loading concentration. In addition, the effect of HDTMA loading concentration, amendment dosage, initial chromium concentration and incubation time on the immobilizing efficiency of H-Monts was investigated.
稳定化技术可以降低土壤中重金属的潜在风险。本研究制备了不同负载量的稳定化添加剂、四甲基铵（TMA）和十六烷基三甲基铵（HDTMA）改性蒙脱石，并对其进行了表征，用于修复六价铬污染土壤。表征结果表明，TMA 改性导致比表面积和孔体积增加，而 HDTMA 改性导致比表面积和孔体积减少。对于 HDTMA 改性蒙脱石（H-Monts），表面活性剂分子的排列模型和结构特征强烈依赖于表面活性剂的负载密度。TMA 改性蒙脱石（T-Monts）的堆积密度依赖性不那么明显。采用改进的毒性特征浸出程序（TCLP）评估了制备的有机蒙脱石对铬的固定能力，结果表明，在不同浸出条件下，T-Monts 和 H-Monts 都能有效地稳定铬。T-Monts 和 H-Monts 表现出的铬浸出行为的比较表明，有机蒙脱石改良剂对铬的固定机制通过两种吸附方法进行。每种方法都涉及不同的功能基团，这取决于浸出 pH 值和表面活性剂负载浓度。此外，还研究了 HDTMA 负载浓度、改良剂用量、初始铬浓度和孵育时间对 H-Monts 固定效率的影响。
