鲍希瓦氏菌吸附Au3+的影响因素及机理研究

吸附是生物回收贵金属的重要环节,本文考察了溶液p H、生物量、初始Au~(3+)浓度和温度对鲍希瓦氏菌吸附Au~(3+)的影响,研究了鲍希瓦氏菌吸附Au~(3+)的动力学和热力学特性,并初步探讨了吸附发生的可能机理.结果表明,p H明显影响鲍希瓦氏菌对Au~(3+)的吸附,最佳p H为2~3.在初始Au~(3+)浓度为115 mg·L~(-1)时,不同温度下90%的Au~(3+)可在10 min内被吸附,4 h后基本达到吸附平衡,且吸附容量随着温度的升高而增加.吸附符合Freundlich等温线模型(R2=0.954),最大吸附容量为148.7 mg·g~(-1).吸附动力学可用拟二级动力学方程描述(R2=0.999).热力学分析显示,鲍希瓦氏菌吸附Au~(3+)是自发的吸热过程.傅里叶红外和X射线光电子能谱分析表明,氨基、羧基和羟基是起主要作用的官能团,其中,质子化的氨基作用机理主要是静电吸附.

Influence factors and mechanisms of Au3+ biosorption by S. haliotis

The effects of pH, biomass dosage, initial Au³⁺ concentration and temperature on the biosorption of Au³⁺ by S.haliotis were evaluated. Meanwhile, kinetics, thermodynamics and possible mechanism were explored. The results indicated that pH was the dominant factor and the optimal initial pH was 2.0~3.0. Within the temperature range in investigation, more than 90% of Au³⁺ was adsorbed within the first 10 min and the equilibrium was reached within 4 h. In addition, the biosorption capacity was found to increase with temperature. Freudlich model provided a good correlation for the biosorption (R²=0.954) with maximum capacity of 148.7 mg·g^-1. The biosorption can be fitted by pseudo-second-order kinetics (R²=0.999). The thermodynamic parameters revealed that the biosorption was a spontaneous and endothermic process. Finally, Fourier transform infrared spectra and XPS revealed that amine, carboxyl, and hydroxyl might the major functional groups involved in the biosorption process and electrostatic sorption was the main mechanism involved in the protonated amino groups.