Diversity in the species and fate of chlorine during TCE reduction by two nZVI with non-identical anaerobic corrosion mechanism
Diversity in the species and fate of chlorine during TCE reduction by two nZVI with non-identical anaerobic corrosion mechanism
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两种具有不同厌氧腐蚀机制的 nZVI 还原 TCE 过程中氯的形态和归宿的多样性
DOI：
10.1016/j.chemosphere.2019.04.158
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发表时间：
2019
期刊：
影响因子：
8.8
通讯作者：
Zhang Li
中科院分区：
文献类型：
--
作者：
Yang Xinmin;Zhang Chong;Liu Fei;Tang Jie;Huang Fuyang;Zhang Li
合成纳米级零价铁（nZVIB）和商业纳米级零价铁（nZVIH）降解TCE的研究已有很多，但厌氧腐蚀对氯脱氯途径和氯形态分布的影响尚不清楚。与nZVIH相比,nZVIBhas更快TCE降解率和Cl−形成率(aq) (kSA, TCE = 3.67±0.85 × 10−4和2.17±0.13 × 10−4 l·h·m−2 andkobs−1,Cl−0.344 = ±0.027 & 0.166 ±0.010 μm·h−1 nZVIB& nZVIH,分别)。通过对厌氧腐蚀过程的XRD、XPS和TEM表征，发现nzvib在溶解-再沉淀机制下发生了剧烈的腐蚀；而nzvih则是温和内向的，保持核壳结构，形成略粗糙和块状的表面。由于腐蚀产物（FeOOH为nZVIBand Fe3O4/γ- fe2o3为nZVIH）和硼在nZVIB表面的催化作用不同，氢解（nZVIB）和氢解（nZVIB）对TCE的优先脱氯途径不相同。还原β-消除（nZVIH）。同时，nzvih的脱氯途径与ZVI相似，还原乙炔的途径绕过了毒性更大的VC的形成。本研究表明，nzvib具有高反应活性，腐蚀速度快，对VC的吸附作用增强，而nzvih具有稳定的核壳结构，吸附的氯较少，这为了解nZVI因非同腐蚀而被忽视的生态风险提供了新的视角。
There have been many studies on TCE degradation by synthesized nanoscale zero-valent iron (nZVIB) and commercial nanoscale zero-valent iron (nZVIH), but the effect of anaerobic corrosion on the dechlorination pathways and speciation distribution of chlorine is still unclear. Compared with nZVIH, nZVIBhas a faster degradation rate of TCE and formation rate of Cl−(aq) (kSA, TCE= 3.67 ± 0.85 × 10−4& 2.17 ± 0.13 × 10−4L·h−1·m−2andkobs, Cl−= 0.344 ± 0.027 & 0.166 ± 0.010 μM·h−1for nZVIB& nZVIH, respectively). Based on the characterization of XRD, XPS and TEM during the anaerobic corrosion, the corrosion of nZVIBwas dramatic under the dissolution-reprecipitation mechanism; but that of nZVIHwas moderate and inward by maintaining the core-shell structure and shaping slightly rough and lumpy surface. Due to the different corrosion products (FeOOH for nZVIBand Fe3O4/γ-Fe2O3for nZVIH) and the catalysis of boron on the nZVIBsurface, the preferential dechlorination pathway of TCE was not identical by hydrogenolysis (nZVIB)vs.reductive β-elimination (nZVIH). Meanwhile, the dechlorination pathway of nZVIHwas similar to that of ZVI and the reductive pathway to acetylene bypassed the formation of more toxic VC. This study shows that the high reactivity of nZVIBresults in rapid corrosion with the side effect of enhanced adsorption of VC while nZVIHhas a stable core-shell structure and less sorbed chlorine, which provides a new sight to access the ecological risk of nZVI due to the overlooked effect of non-identical corrosion.