Multiple adsorption systems and electron-scale insights into the high efficiency coadsorption of a novel assembled cellulose via experiments and DFT calculations

Highlights: • Cellulose is characterized by multiple hydrophilic groups, long chains and large space. • Electrostatic interactions had the greatest impact on the adsorption of Cd and SMZ. • HVUC had advantageous adsorption sites for both Cd and SMZ. • Cd more easily overlapped electron clouds and transferred electrons with HVUC and SMZ^-. • The formation of Cd-SMZ^- complexes led to the bending and folding of SMZ^-. In view of the characteristics of heavy metal and antibiotic compound pollution in the Pearl River Basin in Guangzhou. More scientifically modified cellulose, named HVUC, is characterized by multiple hydrophilic groups, long chains and large space and displays highly efficient adsorption of both Cd and sulfamethoxazole (SMZ) and good adaptability in a wide pH range and at high ion strength. Furthermore, the coadsorption mechanism was elaborated from multiple angles. Multiple adsorption experiments explained the competition and synergy effect in the adsorption process. The electrostatic potential maps indicated that HVUC had advantageous adsorption sites for both Cd and SMZ and that electrostatic interactions had the greatest impact on the adsorption of Cd and SMZ. The electron density and differential charge density images proved that Cd more easily overlapped electron clouds and transferred electrons with HVUC and that SMZ^- and could act as a bridge for SMZ^-. The equilibrium configuration indicated that the formation of Cd-SMZ^- complexes led to the bending and folding of SMZ^-, which was not conducive to overall adsorption when SMZ^- was close to HVUC and could lead to the release of SMZ^- when Cd was close to HVUC, which confirmed the proposed mechanism of complexation-decomplexation-complexation.