Preparation of Fe3O4@GO@MIL-101 nanocomposites and efficient degradation of oxytetracycline hydrochloride by promoting charge separation during the photo-Fenton process

The combination of photocatalysis and Fenton oxidation technology is an efficient strategy to improve the efficiency of oxytetracycline hydrochloride (OTC-HCl) degradation. Herein, a Fe 3 O 4 @GO@MIL-101 composite catalyst bridged with graphene oxide (GO) was obtained by a two-stage hydrothermal method . The introduced graphene oxide layer could inhibit the recombination of electron hole (e − - h + ) pairs by attracting photo-generated electrons from MIL-101 and transferring them to Fe 3 O 4 , observably enhancing the photocatalytic performance of the composite Fe 3 O 4 /MOFs. Under the optimal conditions (initial pH, 10 mmol H 2 O 2 , 0.01 g/L catalyst), the Fe 3 O 4 @GO@MIL-101 + H 2 O 2 +Vis system could achieve a degradation effect of 97.26 % on 70 mg/L OTC-HCl within 50 min Fe 3 O 4 @GO@MIL-101 nanocomposites exhibited good recyclability , were easy to recover after multiple uses, and maintained excellent removal efficiency for pollutants. A series of data demonstrated that in Fe 3 O 4 @GO@MIL-101 + H 2 O 2 +Vis system, the primary active substances involved in OTC-HCl degradation were holes and superoxide radicals , while the contributions of hydroxyl radicals and photo generated electrons were relatively weak. Finally, based on various characterization results and catalyst activity performance, a feasible mechanism for the removal of OTC-HCl by Fenton-like system was proposed.