School of Minerals Processing and Bioengineering, Key Laboratory of Biohydrometallurgy of Ministry of Education, Central South University, Changsha, 410083, China.
State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, 99 Lingcheng West Road, Guiyang, 550081, China.
Environ Pollut. 2021 Oct 1;286:117227. doi: 10.1016/j.envpol.2021.117227. Epub 2021 Apr 24.
Although secondary minerals have great potential for heavy metal removal, their impact on chromium biogeochemistry in subsurface environments associated with dissimilatory iron reducing bacteria (DIRB) remains poorly characterized. Here, we have investigated the mechanisms of biogenic secondary minerals on the rate of Cr(VI) bioreduction with shewanella oneidensis MR-1. Batch results showed that the biogenic secondary minerals, schwertmannite and jarosite, appreciably increased the Cr(VI) bioreduction rate. UV-vis diffuse reflection spectra showed that schwertmannite and jarosite are semiconductive minerals, which can be activated by MR-1, followed by transferred conduction electrons toward Cr(VI). Cyclic voltammetry and Tafel analysis suggested that the resistance of secondary minerals is a dominant factor controlling Cr(VI) bioreduction. In addition, Cr(VI) adsorption on secondary minerals through ligand exchange promoted Cr(VI) bioreduction by decreasing the electron transfer distance between MR-1 and chromate. Fe(III)/Fe(II) cycling in schwertmannite and jarosite also contributed to Cr(VI) bioreduction as reflected by X-ray photoelectron spectroscopy and Fourier transform infrared spectrometer. Complementary characterizations further verified the contributions of Fe(III)/Fe(II) cycling, Cr(VI) adsorption, and conduction band electron transfer to enhanced Cr(VI) bioreduction. This study provides new insights on the understanding of Cr(VI) bioreduction by semiconductor minerals containing sulfate in subsurface environments.
尽管次生矿物在去除重金属方面具有巨大潜力，但它们对与异化铁还原菌（DIRB）相关的地下环境中铬生物地球化学的影响仍未得到充分描述。在这里，我们研究了生物成因次生矿物对 Shewanella oneidensis MR-1 还原 Cr(VI) 速率的影响机制。批量结果表明，生物成因的次生矿物水铁矿和黄钾铁矾显著提高了 Cr(VI) 的生物还原速率。紫外可见漫反射光谱表明，水铁矿和黄钾铁矾是半导体矿物，可被 MR-1 激活，随后将传导电子转移到 Cr(VI)。循环伏安法和塔菲尔分析表明，次生矿物的电阻是控制 Cr(VI)生物还原的主要因素。此外，Cr(VI)通过配体交换吸附在次生矿物上，通过降低 MR-1 和铬酸盐之间的电子转移距离，促进了 Cr(VI)的生物还原。水铁矿和黄钾铁矾中的 Fe(III)/Fe(II)循环也促进了 Cr(VI)的生物还原，这反映在 X 射线光电子能谱和傅里叶变换红外光谱中。补充特征进一步验证了 Fe(III)/Fe(II)循环、Cr(VI)吸附和导带电子转移对增强 Cr(VI)生物还原的贡献。这项研究为理解地下环境中含硫酸盐的半导体矿物对 Cr(VI)的生物还原提供了新的见解。
