School of The Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China; State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China.
School of The Environment and Safety Engineering, Jiangsu University, Zhenjiang 212013, China.
J Hazard Mater. 2015 May 15;288:134-9. doi: 10.1016/j.jhazmat.2015.02.009. Epub 2015 Feb 7.
Accumulation and utilization of heavy metals from wastewater by biological treatment system has aroused great interest. In the present study, a metal-reducing bacterium Shewanella oneidensis MR-1 was used to explore the biofabrication of ZnS nanocrystals from the artificial wastewater. The biogenic H2S produced via the reduction of thiosulfate precipitated the Zn(II) as sulfide extracellularly. Characterization by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and field emission scanning electron microscope (FESEM) confirmed the precipitates as ZnS nanocrystals. The biogenic ZnS nanocrystals appeared spherical in shape with an average diameter of 5 nm and mainly aggregated in the medium and cell surface of S. oneidensis MR-1. UV-vis DRS spectra showed ZnS nanoparticles appeared a strong absorption below 360 nm. Thus, the photocatalytic activity of ZnS was evaluated by the photodegradation of rhodamine B (RhB) under UV irradiation. The biogenic ZnS nanocrystals showed a high level of photodegradation efficiency to RhB coupled with a significant blue-shift of maximum adsorption peak. A detailed analysis indicated the photogenerated holes, rather than hydroxyl radicals, contributed to the photocatalytic decolorization of RhB. This approach of coupling biosynthesis of nanoparticles with heavy metal removal may offer a potential avenue for efficient bioremediation of heavy metal wastewater.
生物处理系统对废水中重金属的积累和利用引起了极大的兴趣。本研究采用一种还原菌 Shewanella oneidensis MR-1，从人工废水中探索生物合成 ZnS 纳米晶体。硫代硫酸盐还原产生的生物 H2S 在外源沉淀 Zn(II)为硫化物。X 射线衍射（XRD）、高分辨率透射电子显微镜（HRTEM）和场发射扫描电子显微镜（FESEM）的特征表明沉淀物为 ZnS 纳米晶体。生物合成的 ZnS 纳米晶体呈球形，平均直径为 5nm，主要聚集在 S. oneidensis MR-1 的培养基和细胞表面。紫外-可见漫反射光谱（UV-vis DRS）表明，ZnS 纳米颗粒在 360nm 以下表现出很强的吸收。因此，通过在紫外光照射下罗丹明 B（RhB）的光降解来评估 ZnS 的光催化活性。生物合成的 ZnS 纳米晶体对 RhB 表现出很高的光降解效率，并伴随着最大吸附峰的显著蓝移。详细分析表明，光生空穴而非羟基自由基对 RhB 的光催化脱色起作用。这种将纳米颗粒生物合成与重金属去除相结合的方法可能为重金属废水的有效生物修复提供了一种潜在途径。
