Despite the widespread use of clay minerals as immobilization reagents for the remediation of heavy-metal-polluted soil,there is limited information on the remediation stability.Sorption stability is considered essential for remediation stability.In this study,therefore,the sorption stability in an ideal solid solution system was investigated using palygorskite(PAL)and cadmium as models.The sorption and desorption behaviors of Cd(Ⅱ)on PAL,including isotherms,kinetics,and various contributing factors(pH,temperature,background electrolytes,and environmental conditions)were studied.The maximum sorption amount was approximately 40 mg/g; the Langmuir isotherm and second kinetic model were the best fits to the sorption process.The thermodynamic parameters calculated from the sorption data at different temperatures indicated that the sorption of Cd(Ⅱ)on PAL was endothermic and favored at higher temperatures.The minimal desorption caused by water and acidic solutions implied that irrigation or runoff and acid rain may have weak effects on sorption.The temperature,pH,and background electrolyte dependence confirmed that the sorption of Cd(Ⅱ)on PAL was stable.The study demonstrated that sorption of Cd(Ⅱ)on PAL was stable under the simulated environmental conditions.The sorption mechanisms were found to involve surface precipitation of CdCO3 and surface complexation with hydroxyl groups.