Advancing membrane fouling control via electrically driven microbubble generation: Phosphidation-enhanced...

Fouling elevates transmembrane pressure, reduces permeate flux, and impairs selectivity, thereby compromising the sustainable operation of membrane-based processes for achieving target water quality. Here, we demonstrated in-situ microbubble generation via enhanced cathodic reduction on phosphidated nickel foam (P-NiF) as a chemical-free strategy for foulant removal with minimal membrane damage. Electrochemical characterization of P-NiF, along with sulfidated and pristine counterparts (S-NiF and NiF), using impedance spectroscopy and cyclic voltammetry, revealed superior electron-transfer activity and a higher density of redox-active sites on P-NiF, consistent with its favorable hydrogen evolution reaction (HER) kinetics as reflected in Tafel slopes. Integrated with a ceramic membrane, P-NiF enabled complete flux recovery of membranes fouled with humic acid, alginate, and silica at 4.0 V, whereas S-NiF required 5 V to achieve comparable performance, with limited flux restoration observed for S-NiF and bare NiF at lower voltages. Near-complete flux recovery was attained with P-NiF at ∼5.30 mWh, compared to ∼8.05 mWh for NiF and S-NiF. Long-term chronoamperometry (280 h) and post-mortem analyses confirmed the electrochemical and structural stability of P-NiF, supporting its prolonged use in microbubble-assisted fouling mitigation. The optimized microbubble-induced scouring exhibited operating costs several orders of magnitude lower than conventional backwashing and chemical cleaning. A dataset-derived mathematical model was developed to predict defouling performance and optimize operating parameters across varying fouling severities, balancing cleaning efficiency and associated costs. The P-NiF HER catalyst-based electrically driven defouling strategy, supported by a computational tool for guiding microbubble-assisted fouling removal, provides a significant advancement toward automated membrane cleaning.