羟基铁矿物在含阴离子污染物水环境中的生物矿化机制及其环境效应

In this study, based on the water pollution problems induced by oxoanions of As, Cr, and P and F- ion present in the water ambiences, and a comprehensive understanding of the researches on the biocatalyzed oxidation of ferrous iron by Acidithiobacillus ferrooxidans or other iron oxidizing bacteria, and the biomineralization formation of iron minerals regulated by bacterial cells and extracellular ploymeric substances (EPS) and their effeciencies of scavenging the toxiic or harmful elements from various environments, the biomineralization mechanism of iron oxyhydroxides with pore structrue involving SO4/Cl ion in the water environments rich in Fe2+ and Acidithiobacillus ferrooxidans, as well as including the anionic contaminants, and the environmental effects of the minerals are investigated. Under the different conditions, the interactions existing in the simulated system composed of bacterial cells/EPS, iron oxyhydroxides and medium including anionic contaminants, and effects of the coexisted substances on the biomineralization formation of iron oxyhydroxides and the capacities of removing the anionic pollutants by the minerals are analyzed, which indicates the correlation of the scavengation mechanism of anionic pollutants and the biomineralization formation of iron oxyhydroxides. The expected results on this study can give the basical theory as an evidence for mineral materials greatly used in the treatment of polluted waters or wastewaters in pratical works.

本研究以污染阴离子(As、Cr、P的含氧根离子及F-)引起的水环境污染问题为出发点，在充分了解不同环境中氧化亚铁硫杆菌等铁细菌可催化氧化Fe2+及其细胞/胞外多聚物可促进铁矿物的生物矿化形成及其衰减有毒有害元素的相关研究结果基础上，展开孔道结构含SO4/Cl羟基铁矿物在富含Fe2+和氧化亚铁硫杆菌、且含有阴离子污染物水环境中的生物矿化机制及其环境效应研究。通过分析各种条件下模拟介质体系"细菌细胞/胞外多聚物-羟基铁矿物-含阴离子污染物介质"中各组分间的相互作用和共存物质对羟基铁矿物的生物矿化形成及其去除污染阴离子效能的影响，以揭示生物矿化作用与污染阴离子衰减机制间的相互关系，预期研究结果可为矿物材料应用于实际污(废)水治理提供基础理论依据。

“铁细菌/胞外多聚物-铁矿物-含污染物环境液相介质”系统中细菌(或胞外多聚物产物)、矿物产物晶型与形貌结构和污染物存在形态及迁移能力这三者间联系的纽带是生物矿化作用。本项目主要探讨了氧化亚铁硫杆菌培养介质和含胞外聚合物(EPS)溶液中铁矿物的生物形成与矿化；污染物对矿物形成和相转化的作用及铁矿物产物对它们的吸持效能；关键环境介质组分和条件的影响。.研究结果表明，在EPS反应溶液中，含高浓度As(III)的EPS铁矿物相的转化明显被抑制；As(III)的加入会影响铁矿物产物的颗粒形貌；温度可促进铁矿物的形成和相转化，同时还会影响As(III)的作用效果。高浓度As(V)会阻碍初始相施威特曼石向黄钾铁矾转化，As(V)的去除与铁矿物产物的晶型和颗粒形貌有关。而在细菌培养介质中，高浓度As/P会抑制Fe2+的生物氧化和初始相铁矿物的转化。As(V)有利于水铁矿形成，As(V)的含氧根离子易与黄钾铁矾结构内的SO42-离子发生置换而被去除；P(V)促进磷酸铁的形成而去除溶液中的P(V)。此外，Tween 80不会影响高浓度As(III)的作用效果，但会明显影响低浓度As(III)对铁矿物产物相转化、颗粒形貌的影响作用及铁矿物对As(III)的吸持效率；Tween 80和高浓度Cr(III)共存，对产物颗粒形貌和元素组成有明显的影响。.铁溶液中细胞和EPS均参与了铁矿物的生物矿化形成，对产物形貌有调控和组装作用，它可促进产物针状颗粒生长及其表面盘状结节新颗粒形成。含阴离子Cl-或SO42-的铁矿物均由Fe2+溶液经细菌A. ferrooxidans细胞氧化形成，反应溶液中阴离子种类和浓度对形成铁矿物的矿相、产物颗粒形貌尺寸均会产生影响。A. ferrooxidans细菌培养介质含有较高含量Fe3+和SO42-利于铁矿物间的相转化。K+优先于NH4+结合到黄铁矾沉淀中初始形成黄钾铁矾产物。上述研究结果可为相关型酸性水环境的治理提供理论依据。