细菌介导水铁矿合成铁硫矿物去除水体铬污染

Bacterial synthesis of iron sulfur minerals from ferrihydrite for aqueous chromium pollutant removal.

为了去除水体中六价铬(Cr(Ⅵ)),利用Shewanella oneidensis MR-1在硫代硫酸盐存在情况下驱动水铁矿转化为铁硫次生矿物制备微生物/矿物杂化体,探究了杂化体对水体中Cr(Ⅵ)去除效果,影响因素及去除机理.物相组成分析和显微形貌观察发现,细菌转化合成的黑色方硫铁矿(FeS)次生矿物纳米颗粒包裹S. oneidensis MR-1细胞从而组装形成了Bio-FeS@MR-1杂化体.所制备的杂化体4h内完全去除了初始浓度26mg/L的Cr(Ⅵ),其效率显著高于单独的等量菌体和FeS次生矿物总和,表明菌体与FeS次生矿物之间存在协同增强效应.Bio-Fe S@MR-1杂化体具有较宽的pH值适用范围(3.0~9.0)和较好的再生能力,其去除Cr(Ⅵ)的效率和重复使用次数均与FeS次生矿物含量和菌体密度成正相关.去除产物中铬主要以Cr(Ⅲ)沉淀物(如Cr2O3和Cr(OH)3)形式存在,表明水体中Cr(Ⅵ)的去除方式包括吸附和还原作用.

In order to remove Cr(Ⅵ) from water, Shewanella oneidensis MR-1 was used to promote the biotransformation of ferrihydrite into iron sulfur secondary minerals in the presence of thiosulfate, and thus producing a microbe/mineral hybrid. The Cr(Ⅵ) removal ability and the influence factors, as well as the Cr(Ⅵ) removal mechanism of the synthesized hybrid were investigated. The phase composition analysis results and microscopic morphology showed that the S. oneidensis MR-1 cells were coated by the black secondary mineral nanoparticles identified as mackinawite(FeS), thereby forming the Bio-FeS@MR-1hybrid.The Cr(Ⅵ) with the initial concentration of 26mg/L had been removed completely by the prepared hybrid within 4h. Its removal amount was significantly higher than the total amount removed by individual bacterial cells and FeS secondary minerals with an equal amount, which demonstrating a synergistic effect between bacterial cells and FeS secondary minerals. The Bio-FeS@MR-1hybrid possesses good tolerance to a wide pH range(3.0~9.0) and excellent regeneration ability. The removal efficiency of aqueous Cr(Ⅵ) and number of repeats were positively correlated with the content of FeS secondary mineral and cell density. The major chromium compounds existing in the Cr(Ⅵ) removal product were Cr(Ⅲ) precipitates(such as Cr2O3and Cr(OH)3), indicating that the removal mechanism of aqueous Cr(Ⅵ) include both adsorption and reduction.