2，4-二氯苯氧乙酸臭氧化过程中过氧化氢的生成

引言2,4-二氯苯氧乙酸(2,4-D,又名2,4-滴)是一种广泛使用的除草剂[1],应用历史较长,是我国主要的除草剂品种之一,用量也比较大。2,4-D属于苯氧羧酸类除草剂的一种,可有效去除阔叶杂草,目前仍广泛用于农作物除草和草坪养护[2]。2,4-D的水溶性较高,挥发性较低,在自然界中难以生物

Formation of hydrogen peroxide during ozonation of 2,4-dichlorophenoxyacetic acid in aqueous solution

The method of degradation of 2,4-dichlorophenoxyacetic acid by ozonation in a cylindrical bubbling tower reactor was proposed.It was revealed that hydrogen peroxide was detected during the ozonation of 2,4-dichlorophenoxyacetic acid.Hydrogen peroxide is useful to decompose ozone in aqueous solution to form hydroxyl radicals.Therefore,hydrogen peroxide has an effect on the 2,4-dichlorophenoxyacetic acid degradation.In order to understand the formation of hydrogen peroxide during ozonation of 2,4-dichlorophenoxyacetic acid,the effect of various experimental parameters on the concentration of hydrogen peroxide was investigated.The experimental results showed that the formation of hydrogen peroxide depended on 2,4-dichlorophenoxyacetic acid in aqueous solution.The yield of hydrogen peroxide produced by ozone decomposition was relatively small and could be neglected.The reaction of H2O2 decay simultaneously took place in reaction solution with the reaction of H2O2 formation.The change of concentration of hydrogen peroxide in aqueous solution indicated an accumulation phase and a consumption phase.As the pH level decreased,the formation rate of hydrogen peroxide also decreased.On the other hand,with the increase of pH level,the decay rate of hydrogen peroxide increased.It is shown that hydrogen peroxide was mainly formed by the direct oxidation of ozone molecule with 2,4-dichlorophenoxyacetic acid.The decay of hydrogen peroxide was induced by the excess hydroxyl radical in aqueous solution.