MnO2/porous spontaneously polarized ceramic with self-powered electric field and superior charge transfer to catalyze ozonation for efficient demulsification

Ozone (O 3 ) 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 3 cannot be ignored. Herein, a MnO 2 /porous spontaneously polarized ceramic (MnO 2 /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 2 ) together with systematic electrochemical characterizations of MnO 2 /PSPC demonstrated its significant charge transfer capability, which is essential for the subsequent reduction of Mn 4+ in the HCO demulsification process. O 3 - MnO 2 /PSPC exhibited excellent demulsification performance with 99 % demulsification rate of cetyltrimethylammonium bromide-stabilized emulsion within 30 min, outperforming O 3 (130 min), O 3 -MnO 2 (60 min), and O 3 -PSPC (90 min). O 3 -MnO 2 /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 3+ /Mn 4+ cycle and O 3 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 3 demulsification performance.