TiO2 mesocrystal reactive electrochemical membrane for rapid removal of organic pollutants from bio-treated coking wastewater

This research investigated a reactive electrochemical membrane (REM) consisting of TiO2 mesocrystals with numerous nanochannels for water treatment. TiO2 mesocrystals were in-situ synthesized within REM by electrochemical method. Compared to the Ti/Ti4O7 and Ebonex REMs, more oxygen vacancies and bulk Ti3 + in TiO2 mesocrystal subunits made the TiO2 mesocrystal REM more conductive and active for generating hydroxyl radicals (∙OH). The results of electrochemical tests indicated the TiO2 mesocrystal REM exhibited the best electrochemical activity. In addition, the TiO2 mesocrystal REM showed enhanced mass transfer and 2 ∼ 5 orders of magnitude increase in the degradation rate of p-Nitrophenol relative to the other REM systems. Density function theory calculation elucidated the TiO2 mesocrystals were more likely to produce ∙OH after electrochemical reduction. Molecular dynamic simulation indicated the water and p-NP molecules can easily enter the nanochannels, leading to the enhanced degradation mechanism. The TiO2 mesocrystal REM demonstrated a prolonged lifetime over 4000 h operated in bipolar mode and high efficiency for the removal of organic pollutants in coking wastewater with energy consumption as low as 30 kWh (kg COD)−1. Our findings highlighted a new mesocrystal synthesis strategy and an innovative REM for water and wastewater treatment. [Display omitted]