Optimization of catalytic sono-praxone hybrid process in the presence of iron oxide-zinc oxide catalyst for the treatment of petroleum wastewater by central composite design

Based on its unique characteristics, oil industry wastewater must be treated before discharging into the environment. The study aimed to optimize the catalytic sonopraxone process in the treatment of petroleum wastewater using a statistical method.

The synthesis of Iron Oxide-Zinc Oxide was carried out by air oxidation and layer-by-layer self-assembly method. XRD, SEM, EDAX, FT-IR, BET, DRS, VSM and TGA techniques were used to investigate the structure. In this study, applied CCD method optimization of pH parameters, reaction time, ozone gas concentration, hydrogen peroxide concentration and catalyst amount in the process. In optimal conditions, BOD5 and TPH removal values, reaction kinetics and synergistic effect of mechanisms were studied. COD, TPH and BOD5 were measured by spectrophotometer (DR6000), GC-FID and incubator, respectively.

The results indicated that the Fe3O4@ZnO structure is well formed. A quadratic model was proposed to model the process based on the correlation coefficient. Based on ANOVA analysis and p and f indices, the proposed model was reported to be significant. Optimum conditions include pH 6.4, ozone concentration 1.3 mg/L.min, hydrogen peroxide concentration 2.5 mL/L, reaction time 51 min and catalyst amount equal to 0.64 g/L. In these conditions, the amount of COD reduction was 82.3 and 70% theoretically and experimentally, respectively. Also, in optimal conditions, BOD5 and TPH removal rates were 90.5% and 85.8%, respectively. The kinetics of the process follows the kinetics of the first order (R2=0.98) and the presence of different mechanisms together causes a synergistic effect and increases the efficiency of the process.

This process can improve the quality of oil effluent based on COD, BOD5, and TPH removal.