In order to study the adsorption mechanism of Cd2+
from aqueous solution and evaluate its potential application in remediation of cadmium contaminated water and soil, a sulfhydryl modified palygorskite material was prepared by high-speed shear gel method. X-ray diffraction (XRD), BET pore structure analysis, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray electron spectroscopy (XPS) were used to characterize the samples before and after adsorption, and to explore the adsorption mechanism. The results showed that both natural and sulfhydryl modified palygorskite could effectively adsorb Cd2+
in aqueous solution, and the adsorption effect of modified palygorskite was better than that of natural palygorskite. The pseudo second order kinetics model is more suitable to describe the dynamic change process of Cd2+
adsorption on palygorskite and sulfhydryl modified palygorskite. The modified palygorskite reaches the adsorption equilibrium in about 90 minutes, which is faster than natural palygorskite. Freundlich isotherm can better describe the adsorption data. Under the experimental conditions, the saturated adsorption capacity of sulfhydryl modified palygorskite is 44.41 mg/g, which is significantly higher than that of natural palygorskite (33.65 mg/g).Combined with XRD diffraction peak analysis, FTIR functional group vibration mode analysis and XPS key element binding energy analysis results, natural palygorskite mainly adsorbs cadmium by surface hydroxyl group and Cd2+
forming surface complexation, and sulfhydryl modified palygorskite also provides a large number of sulfhydryl functional groups as adsorption sites. Complex precipitation is formed by complexing Cd2+
with hydroxyl and sulfhydryl groups on the surface. This study will provide important basic data and technical support for the passivation treatment of cadmium contaminated soil.