Catalytic ozonation of chemical oxygen demaud in high-salt coal chemical waste water by fly ash doped with MnO2

In order to realize the effective treatment of high-salt wastewater from coal chemical industry，various advanced oxidation technologies have been studied in depth. Heterogeneous catalytic oxidation technology is an effective and promising technology，which is essential for the development of high-efficiency catalysts. Therefore，the heterogeneous oxidation technology for ozonation has been developed by leaps and bounds. The active component manganese dioxide was prepared by hydrothermal synthesis，and the granular solid catalyst was prepared by JP3doping molding technology. The catalyst was analyzed by X-ray fluorescence spectroscopy(XRF)，Scanning electron microscopy-X-ray microanalysis(SEM-EDS)，X-ray photoelectron spectroscopy(XPS)，Zeta potential analysis and other characterization techniques. The results show that the catalyst is a mixed multi-layer catalyst with silicon，aluminum，and calcium oxides as the main body and manganese dioxide as the main active component. And the surface of the catalyst has good morphology and has a good pore structure. Catalytic ozonation of organics in high salt water degradation experiments discussed factors such as ozone dosage，catalyst dosage，initial pH and other factors. The results showed that the reaction was carried out for 60 minutes under the conditions JP4of ozone dosage of 10 mg/L and catalyst dosage of 100 g. Afterwards，the COD (chemical oxygen demand) removal rate of high brine is about 60%，and the optimal initial pH of the reaction system is near the isoelectric point of the catalyst. In the study of the reaction mechanism，the addition of PO3- 4proved that the acidic sites on the surface are the active sites for organic degradation; the COD degradation rate of the p-benzoquinone system is only about 45%，while the addition of tert-butanol reaction system can achieve 55% COD degradation rate，so it is proved by adding different kinds of free radical inhibitors that ·O2-2 contributes far more to the degradation of COD than ·OH，and the effect of the addition of inorganic anions on the reaction effect is inconsistent. The concentration of Cl- and HCO-3 When it is 1 000 mg/L，the catalytic effect will decrease by more than 5%，indicating that the anions of free radical trapping agents will significantly reduce the degradation rate of COD.