Iron–molybdenum bimetals incorporated montmorillonite-based catalytic ceramic membrane for heterogenous Fenton reaction towards the degradation of micropollutants in water

Abstract

This study developed an innovative material approach that integrated Fenton catalysis with membrane filtration in a single system using iron–molybdenum bimetal oxides (FeMoO) incorporated montmorillonite (MMT)-based ceramic membrane (FeMoMMTCM) to achieve continuous Fenton reaction for water purification. The embedded bimetallic FeMoO catalyst created abundant active Fe(II) sites on the external and internal surfaces of the ceramic membrane (CM) for H2O2 activation. Using naproxen (NPX) as a model micropollutant in water, the FeMoMMTCM/H2O2 system achieved a 98.6 % removal of NPX (10 mg/L) within a filtration period of 3.4 min through the membrane, in comparison to a 17.5 % removal by FeMoMMTCM filtration with no H2O2 dosing and a 21.1 % removal by the FeMoO-less MMTCM/H2O2 system. The catalytic membrane demonstrated its high NPX removal efficiency over multiple cycles, retaining its effectiveness even in the presence of co-existing ions and organic matter in the water matrix. Furthermore, the FeMoMMTCM/H2O2 system was able to remove nearly 70 % of residual organic pollutants from the actual secondary wastewater effluent. The quenching tests and electro-paramagnetic resonance (EPR) detection confirmed the generation of hydroxyl (OH) and superoxide (O2−) radicals from H2O2. The excellent catalytic performance can be attributed to the Fe-Mo bimetallic catalyst, in which the active Mo(VI)/Mo(IV) cycle can facilitate the Fe(II)/Fe(III) cycle for continuous Fenton reaction. The cost analysis indicates that the low-cost MMT and its low sintering temperature for ceramics would greatly decrease the cost of MMTCM (243.1 US$/m2 vs. 541.5 US$/m2 of alumina-based CM). Overall, the research presents a technical strategy for the fabrication of highly cost-effective catalytic membranes with Fenton reaction for removing micropollutants from water.