Effect of Gas Flow Rate on Degradation of 2,4-D with O<sub>3</sub> and O<sub>3</sub>/H<sub>2</sub>O<sub>2</sub>

Abstract

The effect of gas flow rate on degradation of chlorinated phenoxy acetic acids herbicide 2,4-D(2,4-dichlorophenoxyacetic acid) in aqueous solution with O3 or O 3/H 2O2 process was investigated in a bubbling semi-batch reactor. The experiments were conducted to study the degradation rate constant, mass transfer condition, ozone consumption and formation of byproduct hydrogen peroxide at different gas flow rates. The results show that gas flow rate is a complicated parameter in the process. The contact time of gas and liquid phase varies with different gas flow rate, consequently ozone mass transfer condition changes with different gas flow rates. The production rate of ozone, amount of ozone in the end gas and ozone consumption during the degradation with ozonation and O 3/H2O2 process vary with different of gas flow rates. Hydrogen peroxide is a byproduct during the ozonation or O3/H2O2 process of 2,4-D. The production rate of hydrogen peroxide is also affected by the gas flow rate. In general gas flow rate has both positive and negative effect on the 2,4-D degradation.