Mass transfer and interfacial reaction mechanisms in a novel electro-catalytic membrane contactor for wastewater treatment by O3

The application of ozone (O-3) in wastewater treatment is critically limited by O-3 mass transfer and oxidation capacity. An electro-catalytic membrane contactor was designed to improve O-3 performance in these two aspects simultaneously. Electro-catalytic membrane contact ozonation (ECMCO) has a higher removal rate for nitrobenzene than that of the single membrane contact ozonation and electrolysis process due to the high oxidation potential of hydroxyl free radicals (center dot OH). O-2 mass transfer was promoted through the configuration of the composite membrane; O-3 mass transfer was dominated by the liquid boundary layer. ECMCO produced more OH than that from other methods, and most of the center dot OH quenched itself instead of reacting with organic compounds due to the poor mass transfer between the electro-catalytic layer and bulk liquid. The oxidation capacity of the ECMCO process was limited, but a composite membrane with high porosity and thin electro-catalytic layer may significantly mitigate these limits.