Ozonation treatment of 2-nitrophenolic wastewater using a new gas-inducing reactor

Abstract

Ozonation is a potential chemical process for the treatment of nitrophenolic wastewater. However, due to the low solubility and utilization rate of ozone, a conventional gas-inducing reactor for ozonation treatment has limited app-lication for treating phenolic wastewater. In this study, 2-nitrophenol wastewater ozonation was conducted in a new gas-inducing reactor that has been investigated in our laboratory over the past few years. The ozonation conducted in this reactor can be operated with a higher ozone utilization rate and lower power consumption than a conventional gas-liquid reactor. The ozone utilization rate increases with increasing pH value and can be maintained at over 95%. Kinetic studies show that a pseudo first-order reaction model derived from a two-film theory can describe the ozonation of 2-nitrophenol. Kinetic study of 2-nitrophenol ozonation shows that there are two stages in 2-nitrophenol ozonation. The observed rate constant in the second stage of 2-nitrophenol ozonation is higher than the first stage. A change in the 2-nitrophenol concentration is responsible for the change in the observed rate constant. Below pH 7, the oxidation rate of 2-nitrophenol increases with increasing pH and increasing ozone inlet concentration. This new gas-inducing reactor can improve the ozone utilization rate. The ozonation of 2-nitrophenol can be effectively conducted in this reactor.