The Photocatalytic Ozonation Oxidation Synergistic Degradation on Organic Pollutants In Coal Chemical Phenol-Ammonia Wastewater by Two-Dimensional Nanosheets Bi2WO6

Abstract

In the work, bismuth tungstate (Bi₂WO₆, orthorhombic system) photocatalyst nanomaterial was synthesized by hydrothermal method. The photocatalytic ozonation oxidation synergistic degradation on organic pollutants in coal chemical phenol-ammonia wastewater by Bi₂WO₆ was studied. The effects of ozone (O₃) concentration, catalyst dosage, pH and O₃ flow rate on the degradation efficiency of wastewater were investigated, respectively. The study found that the degradation processes of these four single factors were fitted kinetically and aligned with the pseudo second order kinetics model, and the maximum chemical oxygen demand (COD) removal rate of the coal chemical phenol-ammonia wastewater was 56.34%, 79.03%, 78.63%, and 79.66%, respectively. The COD removal rate reached 80.37% under the optimum reaction conditions. Additionally, the degradation process was optimized, which conformed to the pseudo second order kinetics model. Density functional theory (DFT) calculations showed that the adsorption energies of O₃ at the Bi, W, and O atomic sites were -0.477 eV, -2.604 eV, and -0.421 eV, respectively, on the exposed crystalline surface of (131), indicating that O₃ had a stronger interaction force with W, which was easy to be activated by the surface-transferred electrons to form reactive oxygen species and mineralize the organic pollutants. The catalytic mechanism indicates that the photocatalytic ozonation oxidation is primarily accomplished by producing •OH, ¹O₂, and \(\bullet O_2^-\), which results in the degradation on organic pollutants in coal chemical phenol-ammonia wastewater. The analysis of water quality and GC–MS indicated that most pollutants present in coal chemical phenol-ammonia wastewater had degraded upon treatment. Furthermore, the BOD/COD ratio of coal chemical phenol-ammonia wastewater was increased from 0.25 to 0.32. Moreover, the COD removal rate only decreased to 70.25% after five cycles of the experiment, which demonstrated that the Bi₂WO₆ catalysts had a high stability and reusability, implying that it has great potential for application in coal chemical phenol-ammonia wastewater treatment.