Iron mineral-humic acid complex enhanced Cr(VI) reduction by Shewanella oneidensis MR-1
Iron mineral-humic acid complex enhanced Cr(VI) reduction by Shewanella oneidensis MR-1
复制标题
铁矿物-腐植酸复合物增强 Shewanella oneidensis MR-1 还原 Cr(VI)
DOI：
10.1016/j.chemosphere.2020.125902
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发表时间：
2020-05-01
期刊：
影响因子：
8.8
通讯作者：
Huang, Qiaoyun
中科院分区：
文献类型：
--
作者：
Mohamed, Abdelkader;Yu, Lu;Huang, Qiaoyun
微生物、铁矿物质和腐植酸广泛存在于土壤和水环境中，并在环境过程中密切相互作用。本研究在针铁矿和腐植酸(HA)存在的条件下，模拟实际环境条件，考察了锥形希瓦氏菌MR-1(S.onedensis)对铬(VI)的去除作用。采用扫描电子显微镜(SEM)、能谱(EDS)、X射线光电子能谱(XPS)、电子顺磁共振(EPR)等技术探讨了铬(VI)的还原机理。结果表明，在还原过程8h后，单用圆锥藻对1.0 mM的六价铬的降解率可达65%。同时，在针铁矿或腐植酸存在下，铬(VI)的还原率降至56%。反之，以还原腐植酸(HA(Red))为电子穿梭的三元络合物使铬(VI)的还原速率提高到79%，减少了细菌对针铁矿表面的附着，从而增强了电子传递，使铬(VI)的还原程度提高了1.3倍。XPS分析表明，铬(VI)被还原为铬(III)，最终产物为氢氧化铬(3)和沉淀在细菌细胞表面的三氧化二铬。非洲刺参还能将针铁矿中的Fe(III)还原为Fe(II)，而Fe(II)又还原了Cr(VI)。这些结果表明，铁矿物-腐植酸络合物能够促进微生物还原铬(VI)，并揭示了HA在铬(VI)生物还原过程中的促进作用。这项研究对最复杂体系中的铬(VI)还原动力学和机理提供了全面的见解。(C)2020爱思唯尔有限公司。保留所有权利。
Microorganisms, iron minerals, and humic acid are widely common in the soil and water environment and closely interact within environmental processes. In this study, the Cr(VI) removal by Shewanella oneidensis MR-1 (S. oneidensis) was examined in the presence of goethite and humic acid (HA) to mimic the real environment situation. Scanning electron microscopy (SEM) combined with energy disperse spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) technologies were used to probe the Cr(VI) reduction mechanism. Our results showed that S. oneidensis alone could reduce 65% of 1.0 mM Cr(VI) after 8 h of the reduction process. Meanwhile, Cr(VI) reduction rate was declined to 56% in the presence of goethite or humic acid. Contrary, the Cr(VI) reduction rate was mightily increased to 79% by the ternary complex of S. oneidensis-goethite-HA where reduced humic acid (HA(red)) acted as electron shuttles and diminished the bacterial adhesion to the goethite surface thereby enhanced electron transfer and increased the extent of Cr(VI) reduction by 1.3 fold. XPS analysis indicated that Cr(VI) was reduced to Cr(III), and the final yields were Cr(OH)(3) and Cr2O3 precipitated on the surface of bacterial cells. S. oneidensis could also reduce Fe(III) in goethite to Fe(II), which in turn reduced Cr(VI). These results suggested that iron mineral-humic acid complex could enhance the microbial reduction of Cr(VI) and revealed the promotion role of HA in the Cr(VI) bioreduction process. This study affords inclusive insights on the Cr(VI) reduction kinetics and mechanisms in the most complicated systems. (C) 2020 Elsevier Ltd. All rights reserved.