Co-sorption of phthalate esters and Cd on biochar-sulfhydryl modified montmorillonite composites.

Developing efficient passivating sorption materials for the treatment of combined pollution by phthalate esters (PAEs) and Cd has become a critical focus in environmental protection and soil remediation. In this study, biochar-sulfhydryl modified montmorillonite composites (BC-SHMMT) were synthesized, characterized, and evaluated for the co-sorption of PAEs (DMP, DEP) and Cd. The integration of sulfhydryl-modified montmorillonite (MMT-SH) with biochar improved the material's surface structure, enhancing both co-sorption capacity and structural stability. Molecular dynamics simulation indicated a monolayer chemical sorption of pollutants by BC-SHMMT, in alignment with the sorption theoretical model. In the co-sorption system, the coexistence of pollutants increased the adsorption of Cd and decreased the sorption of PAEs. The smaller molecular size and higher diffusion coefficient of Cd facilitated its pore filling and interaction with oxygen-containing functional groups of the material, leading to competition with PAEs for sorption sites. Notably, the ion exchange and complexation of Cd adsorption by MMT-SH are pivotal in enhancing BC-SHMMT co-sorption capacity. These findings provide valuable insights into the development of eco-friendly novel materials and the improvement of co-pollution remediation efficiency.