Insights into the Ligand Effect in β-CD@Fe[sub.3]O[sub.4] Composites to Activate Peroxymonosulfate for Efficient Degradation of Pharmaceutical Contaminants: A Study Employing Density Functional Theory

This study presents a detailed investigation into the use of β-cyclodextrin (β-CD) encapsulated iron oxide nanoparticle (β-CD@Fe[sub.3]O[sub.4]) composites, modified with different ligands, to activate peroxymonosulfate (PMS) for the degradation of pharmaceutical contaminants, namely, diclofenac, carbamazepine, and erythromycin. The focus is on understanding the ligand effect, particularly using citric acid (CIT), polyethyleneimine (PEI), and cetyl trimethyl ammonium bromide (CTAB), on the degradation performance of these composites. Employing density functional theory (DFT) calculations, this work examines the electronic structure and charge distributions of β-CD@Fe[sub.3]O[sub.4] composites, providing insights into their interaction with various pollutants. The study reveals that the β-CD@PEI@Fe[sub.3]O[sub.4] composite demonstrates superior degradation efficiency due to optimal electrostatic interactions, regardless of the pollutant’s hydrophobicity. On the other hand, β-CD@CIT@Fe[sub.3]O[sub.4] shows moderate efficiency, and β-CD@CTAB@Fe[sub.3]O[sub.4] exhibits selective efficiency, particularly for hydrophobic compounds. These findings underscore the significant role of surface chemistry in modulating the activation of PMS and the degradation of contaminants, opening avenues for designing tailored β-CD composites for environmental remediation.