Modelling and optimisation of catalytic ozonation process assisted by ZrO2-pumice/H2O2 in the degradation of Rhodamine B dye from aqueous environment

Abstract

ABSTRACT This study investigated the performance of ZrO2-pumice/H2O2-catalysed ozonation (O3/H2O2/Zr-pumice) system in the decolourisation of Rhodamine B (RhB) dye from aqueous solutions. Fourier-transform infrared spectroscopy, Scanning Electronic Microscope, X-ray fluorescence, X-ray diffraction, Brunauer-Emmett-Teller surface area, and Barrett-Joyner-Halenda pore size and volume analyses were employed to characterise the Zr-pumice. Central composite design-response surface methodology (CCD-RSM) and artificial neural network (ANN) approaches were employed to model the association between operating variables and RhB removal. CCD-RSM method suggested a reduced second-order polynomial model with R2 = 0.9998, and ANN method developed an ANN model with R2 = 0.9948. The levels of operating variables were displayed to be optimum at pH = 9.31, reaction time = 20 min, Zr-pumice = 0.9 g/L, RhB = 100 mg/L and H2O2 = 4.6 mmol/L, according to CCD-RSM and genetic algorithm approaches. Synergistic effect assessment revealed about 51.9% increase of removal efficiency in the hybrid system of O3/H2O2/Zr-pumice. The findings related to HO• radical-scavenging test illustrated that the major contribution of removal occurs through radical mechanism. Maximum TOC removal was determined to be 64.4% for RhB solution, and the BOD5/COD ratio increased from 0.08 to 0.56 after 150 min reaction time for a textile industry wastewater sample. Reusability test demonstrated that the Zr-pumice has a reasonable recyclability capacity even after five cycles of reuse. In conclusion, the O3/H2O2/Zr-pumice hybrid system can be suggested as a potential process in the treatment of dyeing wastewaters.