Effect of gas flow rate on degradation of 2,4-D with O_3 and O_3/H_2O_2

摘要

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 O_3 or O_3/H_2O_2 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/H_2O_2 process vary with different of gas flow rates. Hydrogen peroxide is a byproduct during the ozonation or O_3/H_2O_2 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.