Optimization of reaction parameters for the sonophotocatalytic degradation of hydroquinone

Abstract

In the present work, the degradation of hydroquinone in synthetic wastewater under sonocatalytic, photocatalytic, and sonophotocatalytic conditions was investigated. The degradation of hydroquinone was investigated in terms of reduction in COD, and the effect of operational parameters including temperature, aeration, frequency, initial hydroquinone concentration, pH, and the TiO₂ dose on the sonophotocatalytic process was examined. We focused on items such as the model formation of H₂O₂ using the sonocatalytic process which was extracted to systemize the operational process and enhance the degradation of hydroquinone. The role and amount of various sizes of the produced bubbles and synergy effect can be detected by our strategy and the integrated system created by the hybrid advanced oxidation process. The degradation values achieved for sonocatalytic, photocatalytic and sonophotocatalytic conditions were approximately 22.3, 76.3, and 100 %, respectively. We found that the maximum hydroquinone degradation in the sonophotocatalysis process was achieved when at a temperature of 25 °C, an aeration of 2 cm³/s, a frequency of 20, 40 and 100 kHZ, a hydroquinone concentration of 100 mg/L, a pH of 7, a TiO₂ dose of 20 g/m², and a fixed radiation intensity of 22.5 µw/cm². Therefore, the sonophotocatalysis process was selected as the optimal process due to a synergy effect equal to 63.5 %. The highest concentration of H₂O₂ was observed at the time of the 12th pass equal to 0.136 g/L. The size of the bubbles and the cavitation hole had a significant effect on the H₂O₂ formation efficiency. The results of this study showed that the sonophotocatalytic hybrid system was able to efficiently degrade hydroquinone compound.