Reduction and stabilization of Cr(VI) in soil by using calcium polysulfide: Catalysis of natural iron oxides
Reduction and stabilization of Cr(VI) in soil by using calcium polysulfide: Catalysis of natural iron oxides
复制标题
使用多硫化钙还原和稳定土壤中的 Cr(VI)：天然氧化铁的催化作用
DOI：
10.1016/j.envres.2020.109992
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发表时间：
2020
影响因子：
8.3
通讯作者：
Liu Yuanyuan
中科院分区：
文献类型：
--
作者：
Zhang Tong;Wang Tao;Wang Wanyu;Liu Bin;Li Wei;Liu Yuanyuan
多硫化钙（CPS）可以修复土壤中铬（VI）污染，而天然氧化铁作为土壤的主要成分会影响修复途径。通过批量动力学试验，研究了天然氧化铁含量、土壤环境条件对土壤中Cr（VI）去除的影响，以及天然氧化铁存在下CPS去除Cr（VI）的机理。结果表明，CPS对土壤中Cr（VI）的去除最符合拟二阶模型，针铁矿的出现使表观速率常数从0.0002 kg mg−1h−1增加到0.0005 kg mg−1h−1。氧化铁的存在增强了CPS对Cr（VI）的去除，形成了土壤的延伸还原性气氛。随着氧化铁含量从0 ~ 9 g kg−1增加，对Cr（VI）的去除率增加，从9 ~ 12 g kg−1下降。与中性土壤相比，在酸性环境中，含氧化铁或不含氧化铁的CPS对土壤中Cr（VI）的去除率从87%提高到100%，主要是由于质子消耗反应和静电吸引作用。修复后，29%的交换态和结合到碳酸盐态的铬含量下降，而24%的结合到铁和氧化锰态的铬含量同时增加。研究结果表明，土壤中天然氧化铁对土壤中Cr（VI）的还原具有催化作用，可显著促进CPS对Cr（VI）污染土壤的修复。
Cr(VI)-contaminated soils could be remediated by using calcium polysulfide (CPS), while natural iron oxides as a main composition of soil would influence the pathways of the remediation. Through kinetic batch tests, the kinetics of Cr(VI) removal from soil, the effects of the contents of natural iron oxides, soil environmental conditions and mechanisms of Cr(VI) removal by using CPS with the presence of natural iron oxides were investigated. The results show that the removal of Cr(VI) by using CPS in soil fitted the pseudo-second-order model best, and the appearance of goethite increased the apparent rate constant from 0.0002 kg mg−1h−1to 0.0005 kg mg−1h−1. The presence of iron oxides enhanced the removal of Cr(VI) by using CPS, and an extended reductive atmosphere of soil was created. The enhancement of Cr(VI) removal increased with the contents of iron oxides from 0 to 9 g kg−1, and declined from 9 to 12 g kg−1. Acidic environment favored the removal of Cr(VI) from soil by using CPS with or without the iron oxides compared to neutral soil and increased it from 87% to 100% because of proton-consuming reactions and electrostatic attraction. Twenty-nine percent of exchangeable and bound-to-carbonates species of chromium declined after the remediation, while 24% bound-to-iron-and-manganese-oxide species increased simultaneously. The findings of the study indicate that natural iron oxides in soils catalyze the reduction of Cr(VI) in soil and facilitate significantly the remediation of Cr(VI)-contaminated soil by using CPS.