The colloidal particles present in natural soil and groundwater systems possess distinctive properties that enable them to migrate across solid surfaces, thereby exerting a significant influence on the distribution of pollutants. While the attachment of colloidal particles to solid surfaces has been extensively investigated, the mechanisms governing their detachment under varying hydrochemical conditions remain largely unexplored. The common interaction between montmorillonite colloids and solid medium (Al2O3) in soil affects the fate of pollutants such as heavy metals. In our study, Al2O3 was used as solid medium to observe the adsorption and desorption behavior of montmorillonite colloids. It was found that the adsorption capacity of Al2O3 to montmorillonite colloids could reach 4.71 mg g−1 (pH 5.0 and 10 mM NaCl concentration). X-ray photoelectron spectroscopy analysis shows that montmorillonite colloids react with the Al2O3 surface mainly through chemical groups with –O–Si bonds. Desorption experiments show that SDS drives desorption by neutralizing and reversing the surface charge of Al2O3, while CTAB directly modifies montmorillonite colloids and introduces steric hindrance to achieve desorption. These research data contribute to a comprehensive understanding of the migration behavior of montmorillonite colloids on solid phases.
Yang et al. (Mon,) studied this question.