Novel ZnO nanorods/Bi2MoO6/MIL-101(Fe) heterostructure immobilized on FTO with boosting photocatalytic activity for tetracycline degradation: Reaction mechanism and toxicity assessment

• ZnO nanorods/Bi 2 MoO 6 /MIL-101(Fe) hierarchical heterostructure was synthesized via the solvothermal method. • Optimal process conditions were obtained by the response surface methodology (RSM). • Catalyst immobilized on FTO glass by using spin coating method. • Elimination of tetracycline intermediates toxicity was evaluated. The new ZnO nanorods/ Bi 2 MoO 6 / MIL-101(Fe) photocatalyst is synthesized by applying the solvothermal method and is characterized by XRD, FTIR, SEM, EDX, TEM, UV–vis DRS, PL, BET, and TGA analyses. The optimal molar composite ratio is ZnO: Bi 2 MoO 6 : MIL-101(Fe) = 2: 1: 0.52 with a 2.3 eV bandgap which has significantly enhanced photocatalytic activity observed in visible light irradiation (420 nm) for tetracycline degradation. The type-II/type-I heterojunction is applied for the photocatalyst reaction mechanism based on the experimental data concerning pollutant concentration = 20 ppm, catalyst dosage = 0.38 g/L, pH = 7, irradiation time = 90 min, optimum conditions, tetracycline removal efficiency, and TOC at 96.1 and 87.4%, respectively. The catalyst is immobilized on the FTO glass by applying the spin coating method, where tetracycline removal efficiency and TOC are obtained at 91.7% and 84.7%, respectively. The toxicity test is run by applying the growth of Escherichia coli (E. coli) bacteria and confirms the non-toxicity of the intermediate products during the photocatalytic process.