Reaction kinetics studies for phenol degradation under the impact of different gas bubbles and pH using gas–liquid discharge plasma

Abstract

A gas–liquid discharge plasma (GLDP) reactor is used to degrade organic pollutants such as phenol. GLDP contains a 7-pin plate system used to enhance phenol degradation in the presence of various pH, and gas bubbles produced from air, O2, O3, CO2, and Ar gases. Experimental outcomes show the impact of solution pH, as phenol degradation efficiencies of 85%, 90%, 96%, and 98% were obtained for pH of 12, 9, 3, and 1, respectively, after 60 min of treatment. This shows that the optimum pH for phenol degradation lies between 1 and 3. Moreover, we explored the influence of gas bubbles generated using various gases, such as air, O2, O3, CO2, and Ar, on phenol degradation. In the presence of O3 gas bubbles, the rate and degree of phenol degradation were significantly increased compared to gas bubbles produced from other gases (O2, CO2, Ar, and air). The degradation competence of phenol by added oxygen remained higher than argon. The performance of the GLDP system at various pH values and gas bubbles was evaluated using kinetic models. Pseudo-zero, first and second reaction kinetics models were used to examine the degradation of phenol. The rate of degradation at different pH and in the presence of gas bubbles follows pseudo-zero-order kinetics. Our GLDP reactor consumed energy of 127.5 J l−1 for phenol degradation under the influence of air bubbles and pH 5. The outcome of this research can help in the design of new reactors for industrial wastewater treatment.