Heterogeneous advanced oxidation processes (AOPs) are widely studied for the destruction of aqueous organic pollutants. However, practical treatment scenarios suffer from the low availability of short-lived hydroxyl radical (.OH) in the bulk phase, due to both the mass transfer limitation and quenching by water constituents such as natural organic matter (NOM). We propose to overcome these challenges by loading iron oxychloride catalyst inside the ceramic ultrafiltration membrane and conducting heterogeneous Fenton reaction inside the membrane channels. With .OHs confined inside the nanopores (~20 nm in diameter), this novel membrane reactor induced a complete removal of various organic pollutants with operating water fluxes of up to 100 L m-2 h-1 (equivalent to 10 s retention time), and the reaction rate constant was significantly enhanced by three orders of magnitude compared to that of the batch reaction. In addition, the membrane reactor with a size excluding NOM (&gt;300 kDa) allowed the selective .OH exposure to the smaller organic pollutants that entered the pores, and it showed excellent resiliency to the representative complex water matrices (simulated surface water and practical sand filtration effluent from a water treatment plant). Moreover, the membrane-confined system exhibited a sustained AOPs reactivity (&gt;24 hours) and can be effectively regenerated for multiple uses. Our results suggest the feasibility of exploiting ultrafiltration membrane based AOPs platforms for degradation of organic pollutants in complex water scenarios.

Membrane-confined heterogeneous Fenton reaction: Mechanism and potential application

ACS Fall 2021

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