共存物质对O_3/H_2O_2工艺降解2,4-D的影响(Ⅱ)氯和过氧化氢动力学分析

Effect of coexisting substances on degradation of 2,4-D in O_3/H_2O_2 process(Ⅱ)

为了模拟实际水体中复杂的水质环境,在去离子水配制的溶液里加入少量无机盐、有机物,以及用自来水、地表水配制2,4-D溶液,采用O3/H2O2工艺处理水溶液中2,4-D污染物,通过跟踪反应液内氯离子和过氧化氢的浓度变化,考察共存物质对脱氯和过氧化氢产生分解的影响。实验结果表明,脱氯量小于2,4-D去除量,2,4-D降解过程中的脱氯主要是由羟基自由基反应所导致的,抑制羟基自由基间接反应的共存物质能抑制脱氯过程;促进羟基自由基间接反应的共存物质能促进脱氯过程,2,4-D全部降解的同时,能达到接近全部脱氯。共存物质对过氧化氢分解速率常数影响较大,多数共存物质对过氧化氢分解速率常数具有促进作用;共存物质对过氧化氢产生速率常数影响较小,多数共存物质对过氧化氢产生速率常数具有抑制作用。

To simulate the complicated surroundings of water quality in actual system, the effect of different coexisting substances such as chlorine and H202 on 2,4-D degradation in O3/H202 process was investigated. Different inorganic salts and organics were added to 2,4-D solution prepared with deionized water, and tap water and surface water were also used to prepare 2, 4-D solution but without other additives. By monitoring concentrations change of chlorine and H202 in aqueous solution, the effect of different coexisting substances on dechlorination and H202 formation and decomposition was studied, The and enhanced by these that improve 2,4-D degradation. At the time when 2,4-D are completely degraded, dechlorination is also closely accomplished. This is favorable for decrease of toxicity in reaction solution. The effect of coexisting substances on rate constants of H2O2 decomposition is larger, and the majority ofthem can increase rate of H202 decomposition. On the contrary, effect of coexisting substances on rate constants of H2O2 formation is less, and the majority of them inhibit H202 formation.