Combined the Photocatalysis and Fenton-like Reaction to Efficiently Remove Sulfadiazine in Water Using g-C3N4/Ag/γ-FeOOH: Insights Into the Degradation Pathway From Density Functional Theory

Yangchen Zhu; Furong Zhao; Fei Wang; Beihai Zhou; Huilun Chen; Rongfang Yuan; Yuxin Liu; Yuefang Chen

doi:10.3389/fchem.2021.742459

Combined the Photocatalysis and Fenton-like Reaction to Efficiently Remove Sulfadiazine in Water Using g-C₃N₄/Ag/γ-FeOOH: Insights Into the Degradation Pathway From Density Functional Theory

Front Chem. 2021 Oct 5:9:742459. doi: 10.3389/fchem.2021.742459. eCollection 2021.

Authors

Yangchen Zhu¹, Furong Zhao¹, Fei Wang¹, Beihai Zhou¹, Huilun Chen¹, Rongfang Yuan¹, Yuxin Liu¹, Yuefang Chen¹

Affiliation

¹ School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing, China.

Abstract

Sulfadiazine (SDZ) is a common antibiotic pollutant in wastewater. Given that it poses a risk as an environmental pollutant, finding effective ways to treat it is important. In this paper, the composite catalytic material g-C₃N₄/Ag/γ-FeOOH was prepared, and its degradation performance was studied. g-C₃N₄/Ag/γ-FeOOH had a superior degradation effect on SDZ than g-C₃N₄ and γ-FeOOH. Compared with different g-C₃N₄ loadings and different catalyst dosages (5, 10, 25, and 50 mg/L), 2 mg/L g-C₃N₄/Ag/γ-FeOOH with a g-C₃N₄ loading of 5.0 wt% has the highest degradation promotion rate for SDZ, reaching up to 258.75% at 600 min. In addition, the photocatalytic enhancement mechanism of the catalyst was studied. Density functional theory (DFT) calculations indicated that the enhancement of photocatalytic activity was related to the narrowing of the forbidden band and the local electron density of the valence band. The bandgap of the catalyst was gradually narrowed from 2.7 to 1.05 eV, which can increase the light absorption intensity and expand the absorption edge. The density of states diagram showed that the local resonance at the interface could effectively improve the separation efficiency of e^--h⁺ pairs. Four degradation paths of SDZ were speculated based on DFT calculations. The analysis confirmed that the degradation path of SDZ primarily included Smiles-type rearrangement, SO₂ extrusion, and S-N bond cleavage processes.

Keywords: degradation pathway; density functional theory; g-C3N4; photocatalysis; sulfadiazine degradation.