MnO/porous spontaneously polarized ceramic with self-powered electric field and superior charge transfer to catalyze ozonation for efficient demulsification.

Ozone (O) demulsification shows great potential in emulsion wastewater treatment due to its strong oxidative properties. However, the low mass transfer efficiency and oxidation selectivity of O cannot be ignored. Herein, a MnO/porous spontaneously polarized ceramic (MnO/PSPC) composite with strong interfacial interactions and self-powered electric field was prepared for heterogeneous catalytic ozonation (HCO) to achieve efficient demulsification. Excellent remanent polarization (0.00858 μC/cm) together with systematic electrochemical characterizations of MnO/PSPC demonstrated its significant charge transfer capability, which is essential for the subsequent reduction of Mn in the HCO demulsification process. O- MnO/PSPC exhibited excellent demulsification performance with 99 % demulsification rate of cetyltrimethylammonium bromide-stabilized emulsion within 30 min, outperforming O (130 min), O-MnO (60 min), and O-PSPC (90 min). O-MnO/PSPC showed effective demulsification of non-/anionic surfactant stabilized emulsions and excellent stability after 5 cycles. Density functional theory calculations together with characterizations illustrate that potential difference-induced rapid electron transfer and water flow-induced self-powered electric field were the fundamental motivation for the fast Mn/Mn cycle and O adsorption/decomposition to generate reactive oxygen species (ROS). Notably, the oxidation of surfactants by ROS led to the coalescence of the oil droplets. This study provides an efficient, sustainable, and energy-efficient method to improve the O demulsification performance.