坡缕石对Sr(Ⅱ)的吸附热力学研究

摘要

The adsorption thermodynamics of Sr (Ⅱ ) on palygorskite in aqueous solu-tions was investigated .In addition ,the effects of contact time ,ionic strength and pH were also investigated by static adsorption method .The results indicate that the adsorp-tion of Sr(Ⅱ) on palygorskite is strongly affected by pH and ionic strength ,and the ion exchange and surface complexation are the main adsorption mechanisms in the adsorp-tion process .The adsorption kinetics of Sr (Ⅱ ) on palygorskite can be described by Lagergren pseudo-second reaction rate model very well . The adsorption isotherm is fitted well by Freundlich and D-R models .Raising temperature is beneficial to adsorp-tion reaction .The thermodynamic parameters ,such as enthalpy (ΔH°) ,entropy (ΔS°) and Gibbs free energy (ΔG°) were calculated using adsorption equilibrium constant obtained from the Langmuir isotherm .The results indicate that the adsorption of Sr (Ⅱ) on palygorskite is a spontaneous and endothermic process .%采用静态吸附法研究了坡缕石对水溶液中Sr(Ⅱ)的吸附热力学特征,并考察了时间、溶液pH值和离子强度对吸附效果的影响.结果表明:Sr(Ⅱ)在坡缕石上的吸附受pH值和离子强度的影响明显;坡缕石对Sr(Ⅱ)的吸附主要通过表面络合和离子交换进行;吸附过程符合Lagergren准二级速率方程;吸附等温线符合Freundlich和D-R模型,升高温度有利于吸附反应的进行;热力学参数ΔH°、ΔS°和ΔG°的计算结果表明,坡缕石对Sr(Ⅱ)的吸附是自发进行的吸热反应.