Effects of non-reducible dissolved solutes on reductive dechlorination of trichloroethylene by ball milled zero valent irons
Effects of non-reducible dissolved solutes on reductive dechlorination of trichloroethylene by ball milled zero valent irons
复制标题
不可还原溶质对球磨零价铁还原脱氯三氯乙烯的影响
DOI：
10.1016/j.jhazmat.2020.122620
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发表时间：
2020
影响因子：
13.6
通讯作者：
He Feng
中科院分区：
文献类型：
--
作者：
Gong Li;Lv Neng;Qi Jianlong;Qiu Xiaojiang;Gu Yawei;He Feng
不可还原性阴离子在氯化烃脱氯过程中影响ZVI的反应活性。然而，它们对ZVI电子效率（epsilon(e)）的影响及其作用机制尚不清楚。本研究以机械化学改性的微尺度硫化和未硫化ZVI颗粒（即S-mZVI（bm）和mZVI(bm)）和三氯乙烯（TCE）作为模型颗粒和污染物来探索这种影响。PO43-作为腐蚀促进剂，提高了两种粒子的初始脱氯速率。然而，在mZVI（bm）脱氯的后期，它作为表面络合剂的钝化作用变得明显，而硫化作用减轻了这种作用，但不抑制脱氯。与增强脱氯相比，PO43-对析氢反应（HER）的促进作用更大，两种颗粒的e均降低了17 ~ 73%。HCO3-对这两种粒子的脱氯作用影响很小，但升高了HER。因此，HCO3- [5 mM]使S-mZVI（bm）和mZVI（bm）的e值分别降低1.9%和22%。与PO43-和HCO3-不同，Cl-和SO42-对两种颗粒的脱氯、HER和e均无显著影响。这些结果表明，尽管共存的阴离子（PO43-和HCO3-）作为腐蚀促进剂可以改善ZVIs的脱氯作用，但它们会导致e降低，缩短颗粒的反应寿命。
Non-reducible solution anions have been well recognized to affect reactivity of ZVI in dechlorinating chlorinated hydrocarbons. However, their effects and corresponding functional mechanisms on electron efficiency (epsilon(e)) of ZVI remain unclear. In this study, mechanochemically modified microscale sulfidated and unsulfidated ZVI particles (i.e., S-mZVI(bm) and mZVI(bm)) and trichloroethylene (TCE) were used as model particles and contaminant to explore such effects. PO43- as a corrosion promoter enhanced initial dechlorination rate by both particles. However, its passivating role as a surface complex agent became significant at the later stage of dechlorination by mZVI(bm), while sulfidation alleviated this effect without inhibition of dechlorination. Compared with enhancing dechlorination, PO43- promoted hydrogen evolution reaction (HER) to a higher extent, decreasing E. for both particles by 17-73 %. HCO3- negligibly affected dechlorination by both particles, while elevated HER. Thus, HCO3- [5 mM] decreased E. for S-mZVI(bm) and mZVI(bm) by 1.9 % and 22 %. Different from PO43- and HCO3-, Cl- and SO42- showed no significant effects on dechlorination, HER, and therefore E. for both particles. These results imply that even though some co-existing anions (i.e., PO43- and HCO3-) acting as corrosion promoters could improve the dechlorination by ZVIs, they would lead to decreased E. and shortened particle reactive lifetime.