Calcium-based catalyst for ozone catalytic oxidation for advanced treatment of high salt organic wastewater

From a green and efficient point of view, a novel calcium-based catalyst (Al2O3-PDA-SA-CaxOy) was prepared in this work using Al2O3 as the supporter, Ca2+ as the main active component and polydopamine (PDA) and sodium alginate (SA) as the modifying substances by a simple impregnation method. The prepared Al2O3-PDA-SA-CaxOy catalyst showed a higher treatment performance for high salt organic wastewater, and removal rate of chemical oxygen demand (COD) was enhanced from 29.81 % to 66.39 % comparing with single ozonation. It showed a good catalytic performance compared with other catalysts reported in the literature. The carboxyl group in SA was cross-linked with Ca2+ for loading more metal Ca, and the N-doped graphitic carbon layer was obtained by PDA carbonization. The carbon layer had a strong aiming effect on metal ions, inhibiting the migration and agglomeration of Ca and facilitating the formation of dispersed calcium active sites (Ca-O). Electron paramagnetic resonance (EPR) and radical quenching tests showed that hydroxyl radical (•OH) and superoxide radical (O2•-) were the reactive oxygen species (ROS) for organics degradation. In conclusion, the Al2O3-PDA-SA-CaxOy catalyst showed a good catalytic performance and used for advanced treatment of high-salt organic wastewater.