施氏矿物Schwertmannite的微生物法合成、鉴定及其对重金属的吸附性能

在K+缺乏的FeSO4-H2O体系(pH 2.5)中,利用氧化亚铁硫杆菌对亚铁的生物氧化作用,合成了一种新型羟基硫酸高铁矿物Schwertmannite(施氏矿物)。借助扫描电镜(SEM)、X射线衍射(XRD)、傅里叶转换红外光谱(FTIR)、电感耦合等离子体原子发射光谱(ICP-AES)等方法对其组成和结构进行了分析与表征,同时还对其重金属吸附性能进行了研究。结果表明,A.ferrooxidans LX5休止细胞可在2 d内将在FeSO4-H2O体系中0.2 mol·L-1 Fe2+全部氧化成Fe3+,溶液pH由起始的2.5下降至2.10,约有15%的Fe2+被转化成红棕色沉淀,余下85%的Fe2+氧化后以Fe3+形式存在于溶液中。鉴定结果表明合成的红棕色羟基硫酸高铁沉淀为施氏矿物。吸附试验表明,施氏矿物对重金属阳离子Cu2+,Zn2+与 Cr3+的吸附受pH的控制,吸附率随pH的升高而增加,约在6.0～7.0时达到最大吸附率。当溶液中三种金属离子浓度为50 mg·L-1时,最大吸持率分别为99.3%,99.4%与87.6%。     

Quantification of the inorganic phase of the pelagic aggregates from an iron contaminated lake by means of Raman spectroscopy

A semi-quantitative investigation of the inorganic phase of pelagic, iron-rich aggregates (iron snow, IS) formed in an iron polluted aquatic environment was performed by means of Raman spectroscopy. IS samples were collected from two basins of an acidic lignite mine lake and at two different water depths. Although the water chemistry differed at all four sites with respect to oxygen, pH, and, Fe(II) concentrations, the Raman analyses showed that the main mineral formed was schwertmannite (ideal formula: Fe₈O₈(OH)₆SO₄) with concentrations of more than 88% in all IS samples. To determine potential differences in the microbial communities of the IS samples we used denaturing gradient gel electrophoresis. Microbial communities differed between two basins, but showed similarities between redoxcline and deeper water layers of IS samples from the same basin. Surprisingly, these microbiological differences did not lead to strikingly qualitative similarities in the mineral composition, although the initial step in mineral formation, the oxidation of Fe(II) to Fe(III), is a pure microbial process at low pH. Thus, a semi-quantitative method was necessary to elucidate differences in the consecutive mineralization process which is apparently more controlled by water geochemical conditions.