Accelerated Fe(III)/Fe(II) cycle couples with in-situ generated H2O2 boosting visible light-induced Fenton-like oxidation

Abstract

Conventional Fenton process operated along with high economic cost due to the requirement of highly acidic pH and an enormous addition of H2O2. And the low conversion rate of Fe(III)/Fe(II) may lead to decline of oxidation performance during the process. Here, we constructed a visible light-induced heterogeneous Fenton-like process on a novel Fenton-like catalyst which consisted of immobilized Fe(III)-TiO2 microspheres as Fenton-like reagent and g-C3N4-porphyrin lamella as in-situ H2O2 donor. The immobilized Fe species showed good stability and reduced the loss of Fe during Fenton-like process. Meanwhile, taking advantage of interfacial charge transfer (IFCT) effect among Fe(III)-TiO2 microspheres, the transformation from Fe(III) to Fe(II) was accelerated by photo-induced electrons from conduction band of the microspheres. And the π–π interaction between porphyrin and g-C3N4 also strikingly promoted the in-situ H2O2 production, which also boosted the Fenton-like process along with the IFCT effect. Stronger electron spin resonance signal of •OH confirmed the boost mentioned above and indicated that g-C3N4-porphyrin provided H2O2 in abundance for the Fenton-like process. This new Fenton-like catalyst exhibited superior oxidation performance and the optimum catalyst TFMS-CP0.1 achieved the removal of 92.6 % and 84.6 % towards phenol and hydroquinone in 3 h, respectively, and 88.2 % towards MO in 1 h. This work proposed a credible mechanism of visible light-induced Fenton-like process and achieved efficient oxidative degradation of the organic contaminant.