(Fe3+)-UVC-(aliphatic/phenolic carboxyl acids) systems for diethyl phthalate ester degradation: A density functional theory (DFT) and experimental study

Abstract

Diethyl phthalate ester (DEP) can be degraded in Fe3+-UV- aliphatic/phenolic carboxyl acids systems, and the degradation can be significantly influenced by different physical chemical properties of the organic acids. In this study, a density function theory (DFT) approach combined with multilinear regression analysis demonstrates that the lowest unoccupied molecular orbital energy (ELUMO) significantly negatively influenced DEP degradation. The correlation coefficient of the regression is −19.3 mM L−1 h−1. The standardized partial correlation coefficient is −0.674. The aliphatic acids group has higher catalytic ability than the phenolic carboxyl acids group, and by shifting the dominant LUMO configuration from C3s3d to Fe4s3d orbitals, Fe3+ significantly accelerates the catalytic reactions of the aliphatic acids/UV systems. Further analysis demonstrates that electron withdrawing hydroxyl group on the aliphatic acids increases the photo catalytic effects of aliphatic acids/UV system. This study highlights the important role of ELUMO of organic acids on their photocatalytic ability towards degradation of organic pollutants.