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%。

Characterization and Heavy Metal Adsorption Properties of Schwertmannite Synthesized by Bacterial Oxidation of Ferrous Sulfate Solutions

An amorphous ferric hydroxysulfate named schwertmannite was synthesized by using bacterial oxidation of ferrous iron by resting A. ferrooxidans cells in acid ferrous sulfate solution (pH 2.5). The identification of the bacterially oxidized iron precipitate was carried out by SEM, XRD, FTIR and chemical analysis. Results showed that resting cells of A. ferrooxidans LX5 could completely oxidize ferrous ions to ferric ions in the FeSO4-H2O system after 2 days of incubation. The solution pH decreased from an initial 2.5 to 2.10, and about 15% of the ferrous iron was transformed into the red-brown precipitates. The subsequent characterization of the precipitates showed that the biotic, synthetic ferric hydroxysulfate was schwertmannite. Sorption edge measurement showed that the adsorption behavior of metal cations (e. g., Cu2+, Zn2+ and Cr3+) was pH-dependent. The adsorption increased with an increase in pH, and the maximum was found in a pH range of 6.0-7.0. For solution concentration of 50 mg x L(-1), the maximum adsorption efficiencies of Cu2+, Zn2+ and Cr3+ were 99.3%, 99.4% and 87.6%, respectively.