【摘要】 采用纳秒级脉冲辐解技术研究了偶氮染料甲基橙在水溶液中与羟基 (·OH)、水合电子 (e-aq)、氢原子 (·H)的反应 .对反应产生的瞬态图谱作了归属 ,提出了相应的反应机理 ,并通过准一级动力学模拟 ,首次求得了甲基橙与这三个瞬态粒子的反应速率常数 .研究表明 :·OH ,e-aq和·H均能破坏甲基橙中的偶氮～苯环的共轭基团 ,导致其脱色 .·OH主要加成到甲基橙的偶氮键和带甲氨基的苯环上 ,形成相应的加成物 ;e-aq则主要进攻与磺酸根相连的苯环 ,生成的阴离子自由基迅速质子化成偕腙肼自由基 ;·H进攻甲基橙形成含肼撑结构的自由基 .甲基橙与·OH ,e-aq和·H的反应速率常数分别为 5 7× 10 9,7 2× 10 9和 1 2× 10 10 dm3 ·mol-1·s-1.这些结果将有助于人们进一步了解偶氮染料降解的本质 ,从而为该类染料废水的降解处理提供理论基础 .更多还原

【Abstract】 The kinetics and mechanisms of the reaction of azo dye methyl orange with ·OH, e- aq and ·H in dilute aqueous solutions have been studied using pulse radiolysis. It is shown that the three radicals can all destroy the conjugative system made up of azo group and aryl rings, resulting in the decoloration of methyl orange. ·OH radicals mainly attack the azo group and the aryl ring bearing methylamino group, forming corresponding OH-adducts. Under the attack of e- aq, methyl orange undergoes H+ catalyzed reduction, leading to the formation of hydrazyl radicals. ·H radicals mainly induce the reductive addition to methyl orange, producing hydrazo type radicals. The rate constants for the reaction of methyl orange with ·OH, e- aq and ·H are 5.7×109, 7.2×109 and 1.2×10 10 dm3·mol -1·s -1 respectively. These results shed light on the degradation mechanism of hydrosoluble azo-dyes in aqueous solution and hence provide the theoretical foundation for the treatment of the water contaminated with this class of compounds.更多还原