Catalytic performance and mechanism of PTFE modified NiCo2O4 in high-salt organic wastewater treatment during wet air oxidation at ambient pressure

Abstract

High temperatures and high pressures restrict the application of catalytic wet air oxidation (CWAO). Thus, realizing the high performance of CWAO under ambient pressure (AP-CWAO) is attractive. In this study, hydrophobic modification by polytetrafluoroethylene (PTFE) was adopted to enhance the O2 transfer and salts resistibility of hollow microspheres NiCo2O4 (HM-NiCo2O4), for harvesting an efficient catalyst of AP-CWAO to treat high-salt wastewater. Under ambient pressure in 10 g/L NaCl solution, PTFE modified HM-NiCo2O4 (PHM-NiCo2O4) can catalyze O2 to realize about 70 % mineralization of bisphenol A (BPA, 100 mg/L) within 240 min at 80 ℃, while it is only about 50 % for HM-NiCo2O4. Density functional theory calculations and molecular dynamics simulations show that PTFE indeed can enhance O2 transfer and salt resistibility of HM-NiCo2O4. HO•, O2•-, and 1O2 all contribute to the degradation of BPA in presence of O2. These reactive oxygen species generate based on Mars-van Krevelen mechanism.