低温等离子体对直接染料废水的脱色研究

Research on Decolorization of Direct Dyes by Low Temperature Plasma

染料废水色度高,且其存在复杂的环状结构,一般处理方法很难获得理想的处理效果.采用直接草绿和直接橘黄配制模拟染料废水,将介质阻挡放电低温等离子体技术应用于直接染料废水脱色研究.研究结果表明:介质阻挡放电低温等离子体处理直接染料可获得的脱色率与染料结构的复杂程度呈负相关.放电功率的增高、介质间距的降低、溶液浓度的减小均有利于获得较高的脱色率.当放电功率为8.5kW,介质间距为5mm,溶液浓度为100mg·L-1时,直接橘黄和直接草绿获得98%脱色率所需时间分别为8min和18min.延长放电时间可以部分补偿因放电功率不足或介质间距过高带来的脱色率降低,但无法补偿因浓度增高带来的脱色率下降.在研究测试的400mg·L-1溶液浓度范围内,直接染料的脱色反应符合假一级反应动力学方程.低温等离子体技术处理直接染料所获得的脱色效果可以满足深度处理技术要求.

Dyeing wastewater is of deep color, and it is hard to treat for the occurrence of cyclic auxochrome groups. Decolorization of direct dyes was studied by dielectric barrier discharge plasma. Chlorantine fast green 5GLL and direct yellow G were chosen to simulate the wastewater. The results showed：The complexity of the molecular structure had negative correlation to the decolorization rate. The decolorization rate rose with the rise of discharge power, decrease of air gaps and concentration of dye in the initial stage of the reaction. The decolotization rates of direct dyes achieved 980/00, when the discharge power was 8.5 kW,air gaps were 5 mm,the concentration of direct dyes were 100 mg L-1 , and the discharge time cumulated to 8 rain and 18 min. The difference decolorization rate caused by reducing discharge power and increasing air gaps was partially compensated by extension the reaction time, but the difference caused by increasing concentration could not be compensated at all. The decolorization reaction followed pseudo first order kinetics equation when the concentration of direct dyes was under 400 mg L-1. The result meets the requirements of deep processing.