One-dimensional structured IrO₂ nanorods modified membrane for electrochemical anti-fouling in filtration of oily wastewater

An electrochemical antifouling filtration apparatus was designed to mitigate the fouling effect, the most significant challenge to the membrane filtration process. The utilized membrane element was fabricated by a conductive 1D IrO₂ nanorod (NR) layer, serving as both the electrode and the filtration media. The 1D IrO₂ NRs coating was modified on Al₂O₃ ceramic membrane using a facile thermal decomposition method from the mixtures of chloride precursor solution with the addition of Sb. The distinct 1D morphology of coating showed rough surface and high porosity, possessing surface area of 149.2 m²/g. The sheet resistance of the fabricated layer could be further reduced through the addition of Ru in order to improve the electrical and electrochemical performance. When electrochemical reactions were used for fouling control at high solution conductivity, the extent of fouling was decreased by at least 20% at 0.15 A, with time-average permeate flux enhanced by almost 44% owing to the generated gas bubbles layer and reactive intermediates on the membrane surface. The membrane fouling can also be significantly minimized by electrophoretic effect, when no appreciable current is passed through the system at desired electric field strength. In contrast with uncoated Al₂O₃ membrane which showed rapid decline of permeate flux after only 40 min of operation, the 1D Sb and Ru doped IrO₂ NRs membrane exhibited only 25.2% drop in permeate fluxes after 2.8 h of operation at the electric field strength of 13 V/cm. Therefore, the designed electrochemical filtration system with 1D Sb and Ru doped IrO₂ NRs membrane provides a promising alternative for membrane fouling control with electrochemical reactions and/or electrophoresis as the main working effects.