水溶液中活性染料的紫外光降解脱色

Degradation of reactive dyes by UV-light in aqueous solution

以低压紫外汞灯为光源,在无光催化剂及促进剂条件下,探讨紫外光对通氧水溶液中活性染料的光降解脱色特性和主要影响因素,以及不同结构类型活性染料的紫外光脱色降解性能。结果表明,溶液pH值、染料浓度、光照时间及母体结构类型对活性黄X-R染料溶液的脱色率有较大影响;染料的光降解脱色率随溶液pH值增大而降低,酸性条件有助于染料母体结构的降解消色;活性黄X-R染料的光降解脱色率随其质量浓度增加(50 mg/L增大到120 mg/L),呈线性降低;染料的光降解脱色速率在起始阶段较快,并随一定范围内处理时间的延长,其脱色率增大;染料结构类型中,以偶氮芳环类和偶氮杂环类为母体的染料容易被紫外光直接降解脱色,但偶氮类母体中引入中心金属离子Cu(Ⅱ)后,其降解脱色率显著降低。染料重氮组分及/或偶合组分中取代基越复杂,基团越多,其光降解脱色性越差,而染料活性基则对光降解脱色影响较小。

Taking a low-pressure mercury violet lamp as light source, the photodegradation characteristics and parameters of re- active dyes in oxygenated aqueous solution without any photocatalyst and promoters is discussed. The degradation of reactive dyes with different molecular structures is investigated. The results show that the pH value, dye concentration and parent structure, and the light radiation time has significantly effect on decolorization rate of Reactive Yellow X-R. The decolorization rate decreases with the increase of pH value and concentration （50 -12.0 mg/L）, and the acidic medium is more helpful. High decoloration rate is observed in initial degradation stage, and the efficiency of color degradation increases with time. The decol- orization rate is fast at the beginning, and getting higher with reaction time. The azo reactive dyes with aromatic group and het- erocyclic rings in the parent structure degrade readily by UV-light, but their decolorization rate decreases significantly after the introduction of coordination metal ion Cu（ Ⅱ）into the parent structure. The more complex and more substitutes the diazo com- ponent and/or coupling component has, the lower the decolorization rate is, but the reactive groups have little effect on the decolorization rate.