Efficient degradation of antibiotics by oxygen vacancy-LaFeO3/polystyrene-driven photo-Fenton system: Highlight the impacts of molecular structures

Abstract

The removal efficiencies of tetracycline antibiotics (TCs) by the OVs-LFO/PS-driven photo-Fenton system were studied. The effects of molecular structure on the removal efficiencies of tetracycline hydrochloride (TC), oxytetracycline hydrochloride (OTC), chlortetracycline hydrochloride (CTC), doxycycline hydrochloride (DOX), minocycline hydrochloride (MH) and metacycline hydrochloride (MTC) were investigated by theoretical calculations and statistical analysis. It can be found that the removal efficiencies of all TCs were >87.00 % (96.51 %, 90.25 %, 87.90 %, 90.43 %, 92.48 % and 90.30 %, respectively). The results showed that three parameters related to molecular orbitals (the energy gap (ΔE, 30.24 %), the highest occupied molecular orbital energy (EHOMO, 27.70 %) and the vertical ionization potential (VIP, 26.54 %)) had relatively large contributions (84.48 % in total) to the removal efficiencies. The reason for the high effect of ΔE on the removal efficiencies was subsequently explored and further verified by the removal processes of other four pollutants. The degradation pattern of TCs was further studied by obtaining the Fukui index (f0 and f− values) of TCs through DFT calculations. According to the detection and analysis results of intermediates, DFT calculations can be applied to predict the degradation of pollutants with the different structure. The study can provide clues to predict the potential and pathways for the oxidative degradation of pollutants with different molecular structures in wastewater treatment.