Enhancement of the heterogeneous photo-Fenton performance of GO/MIL-100(Fe)@Fe3O4 heterostructures for erythromycin degradation through accelerating Fe(ii) generation

Abstract

The slow rate of the Fe³⁺/Fe²⁺ cycle has decreased the efficiency of photo-Fenton technology for wastewater treatment. Here, a novel GO/MIL-100(Fe)@Fe₃O₄ heterostructure was constructed by growing Fe₃O₄ nanoparticles and MIL-100(Fe) onto GO, thus accelerating the Fe³⁺/Fe²⁺ cycle and improving catalytic activity, and it was used as a heterogeneous photo-Fenton catalyst for ERY degradation. The catalyst was fully characterized by TEM, XRD, Raman spectroscopy, XPS, N₂ adsorption–desorption and UV-vis DRS. The influences of initial solution pH, H₂O₂ concentration and catalyst dosage on ERY degradation were investigated. Under optimal conditions (initial pH of 4.03, 10.0 mM H₂O₂, 0.1 g L⁻¹ catalyst), the GO/MIL-100(Fe)@Fe₃O₄ + H₂O₂ + vis system removed 97.3% of ERY (0.1 mmol L⁻¹) within 60 min, and the pseudo-first-order rate constant was 0.0575 min⁻¹. Furthermore, the catalyst showed favorable stability, maintaining excellent catalytic activity even after 4 cycles. A possible degradation mechanism of ERY was proposed based on the results of characterization, ERY degradation, and reactive species analysis. Fe₃O₄, MIL-100(Fe) and GO in the catalyst showed synergistic effects; the photo-induced electrons from MIL-100(Fe) could be immediately transferred to Fe₃O₄, promoting Fe³⁺ reduction to Fe²⁺ in the photo-Fenton reaction. GO in the catalyst could promote electron transfer from MIL-100(Fe) and organics to Fe₃O₄, significantly promoting the Fe³⁺/Fe²⁺ cycle.