Optimization of catalytic wet peroxide oxidation of carbofuran by Ti-LaFeO3 dual photocatalyst

Abstract

In this study, a robustly dual catalyst of Ti-substituted LaFeO 3 (Ti-LaFeO3) was synthesized in a quest for developing a simultaneous photocatalytic wet peroxide oxidation (photo-CWPO). In this feature, Ti-LaFeO3 was utilized to degrade carbofuran (CBF) by photocatalysis and photo-Fenton processes under UV and visible light. EDX and XRD analyses confirmed the partial substitution of La by Ti in the lattice of LaFeO3. Other analyses such as SEM, TEM, HRTEM, SAED, and FTIR characterized the structure and morphology of the catalyst. Furthermore, the reflectance spectra indicated a remarkable bandgap of the modified catalyst (1.96 eV). Compared to pristine LaFeO3, Ti-LaFeO3 showed higher degradation of CBF due to the reduced bandgap. A central composite design was utilized for the optimization of the experimental parameters such as the CBF initial concentration, loading of Ti-LaFeO3, H2O2 dose, and pH. Under the optimal conditions (initial CBF concentration = 7.0 mg/L, catalyst loading = 700 mg/L, H2O2 dose = 480 mg/L, and pH 3.0), CBF removal was 90.6% after 180 min of the CWPO process. Furthermore, the catalyst was reused in five consecutive cycles to evaluate its stability. The leaching of iron was measured to assess its role in the degradation of CBF. The oxidation pathway of CBF was proposed according to the identified transformation products by tandem mass spectrometry. The mechanism investigation indicated an enhanced degradation of CBF by both photocatalytic and Fenton-like reactions using Ti-LaFeO3.