铅离子的生物吸附动力学及吸附热力学研究

Study of Biosorption Kinetics and Thermodynamics of Lead

目的:研究非活性深红酵母(Rhodotorula rubra)对重金属离子Pb2+的生物吸附热力学和动力学特性。方法:采用恒温摇床振荡吸附的实验方法,研究Pb2+生物吸附的动力学和热力学,并以适当的数学模型对实验数据进行拟合;对吸附前后的酵母进行红外光谱及X射线光电子能谱分析。结果:在20℃～45℃温度范围内,吸附5min时即达到了饱和吸附量的80%以上,2h左右达到平衡;深红酵母对Pb2+的生物吸附过程适宜用Elovich方程来描述;由二级动力学方程计算的生物吸附活化能为21.56kJ/mol;生物吸附平衡可用Langmuir等温式、Freundlich等温式及Dubinin-Radushkevich等温式来描述,拟合相关系数均接近0.99;Langmuir方程计算所得ΔH0为13.93kJ/mol。结论:深红酵母对Pb2+的生物吸附是非均相的扩散过程,由快速吸附和慢速吸附两个阶段组成,以物理吸附为主,并伴随有化学吸附。

Objective：The biosorption thermodynamics and kinetics of heavy metal ion Pb^2＋ by unactive Rhodotorula rubra were studied.Method：The biosorption kinetics and thermodynamics experiments of Pb^2＋ were done in shaker under constant temperature.And the data were fitted using appropriate models.Infrared spectral and X-ray photoelectron analyses were conducted in order to compare the yeast before and after biosorption.Result：In the range of 20℃-45℃,the 80% of the saturation adsorption capacity was reached in 5min and the adsorption equilibrium was reached in 2h.The biosorption kinetics data could be fitted using Elovich equation best of all;the adsorption activate energy of 21.56kJ/mol could be calculated using second-order kinetics equation.The biosorption equilibrium could be described well using Langmuir,Freundlich and Dubinin-Radushkevich adsorption isotherms,all the fitting coefficients approaching 0.99,and ΔH^0 was 13.93kJ/mol by using Langmuir equation.Conclusion：Biosorption of Pb^2＋ by R.rubra was a process of unsymmetrical phase diffusion,including a rapid course and a followed slower course.Physical adsorption played a leading function and chemical adsorption was also involved in this process,but not the major mechanism.