厌氧条件下芽孢杆菌Bacillus sp.dwc-2对模拟地下水中U(VI)的吸附行为研究

Adsorption of U(VI)on Bacillus sp.dwc-2 in simulated groundwater under anaerobic conditions

本文在厌氧条件下,研究了西南地区土壤中一种典型微生物芽孢杆菌 Bacillus sp .dwc-2对模拟地下水U(Ⅵ)的吸附行为,重点考察了时间、pH、NaHCO3、温度、阴离子、腐殖酸以及富里酸对吸附的影响,并利用SEM、EDS、FT-IR和XRD对样品进行了表征。结果表明:在pH 7.0、[NaHCO3]=5 mmol·L^-1 和 T =30 ℃条件下,芽孢杆菌对U(Ⅵ)有最大的吸附率。初始pH值升高及阴离子浓度增大会抑制芽孢杆菌对U(Ⅵ)的吸附;随着U(Ⅵ)初始浓度的增加,芽孢杆菌对U(Ⅵ)的吸附率呈先增加后降低的趋势;腐殖酸和富里酸则会抑制芽孢杆菌吸附U(Ⅵ)。吸附均在120 h达到平衡,吸附过程均符合准二级动力学模型,说明吸附以化学吸附为主。Langmuir和Freundlich模型拟合结果显示,芽孢杆菌吸附U(Ⅵ)为单分子层吸附。上述结果可为真实环境中微生物吸附U(Ⅵ)提供基础数据和参考。

The adsorption behavior and the effect of various experimental conditions on U(Ⅵ)adsorption by Bacillus sp .dwc-2 were investigated in simulated groundwater under anaerobic conditions,and SEM,EDS,FT-IR and XRD were conducted.The results show that anions inhibit U(Ⅵ)biosorption,and the maximum U(Ⅵ)adsorption rate is achieved at pH 7.0,[NaHCO3]=5 mmol·L^-1 , T =30 ℃ and 24 h.The adsorption capacity decreases with increasing of initial pH and anions concentrations,and the adsorption rates of U(Ⅵ)by bacillus sp .dwc-2 increase and then decrease with the increase of the U(Ⅵ)initial concentration.With the increase ofHumic acid and Fulvic acid,the U(Ⅵ)adsorption rate on bacillus sp .dwc-2 decreases.The adsorption equilibrium time is 120 h.The adsorption process is well described by pseudo-second-order kinetics model,which indicates that the adsorption process may be chemical adsorption.Langmuir and Freundlich isotherm model results show that the U(Ⅵ)adsorption on bacillus sp .dwc-2 is monolayer.Our study provides basic data and reference for U(Ⅵ)biosorption under real environment.