Expanding the pH range of Fenton-like reactions for pollutant degradation: The impact of acidic microenvironments.

Heterogeneous Fenton reactions offer the opportunities to overcome iron sludge accumulation and limited recyclability of existing homogeneous Fenton process, but the sharp attenuation in their reactivity at near-neutral and even higher pH conditions, still remains a formidable challenge. In this work, we report a versatile and robust approach to create a local acidic microenvironment on BiOI with graphene oxide bonding, enabling the heterogeneous Fenton (BiOI@rGO/H2O2) system to sustainably degrade organic pollutants over a wide pH range (3.0-10.0). Notably, BiOI@rGO exhibits a superior catalytic activity (∼100 % removal) and robust durability (over ten cycles) in degrading bisphenol A and tetracycline, even in real wastewater scenarios. Furthermore, immobilizing the BiOI@rGO on carbon felt to establish a continuous flow-through device achieves a stable treatment performance with a degradation efficiency exceeding 98 % for micropollutants over a continuous operation. This work provides a paradigm for constructing an acidic microenvironment on the catalyst to surmount the pH limitations of the heterogeneous Fenton reactions for advanced water purification.