电解法处理罗丹明B生产废水的工艺及机制研究

Treatment and degradation mechanism of the wastewater from rhodamine B production

随着染料工业的不断发展,其生产过程中产生的废水已成为主要的工业水体污染源。采用电解法处理罗丹明B生产废水,首先研究了极板材料和电流密度对废水处理效果的影响,结果表明:分别以镍板和RuO2-IrO2-TiO2/Ti钛网为阴、阳极,控制极间距3cm,电流密度2.0A/dm^2,电解时间40min,废水COD去除率可达44.3%,脱色率高达94.7%。然后通过H型电解槽实验和红外光谱对电解法处理罗丹明B生产废水的机制进行了探究,初步推断:阳极表面生成的氯气溶于水生成次氯酸,次氯酸氧化破坏废水中有机物分子的发色基团并促使其发生分解,生成的小分子有机物由于水溶性较差,被阳极表面生成的氯气以及阴极表面生成的氢气浮选出来,从而最终实现废水COD的降解和色度的去除。

With the development of dye industry,the resulting wastewater has become the main source of industrial water pollution.In this work,an electrolytic method was employed to treat the wastewater produced during the production of rhodamine B.Firstly,the influence of varying the electrode materials and current density on the wastewater treatment were studied in detail.The COD reduction ratio and decolorization ratio of the wastewater were 44.3% and 94.7% respectively,after electrolyzing for 40 min at a current density of 2.0 A/dm^2 when using RuO2-IrO2-TiO2/Ti and a nickel plate as the anode and cathode respectively.The distance between the anode and cathode was kept at 3 cm,and the current density was controlled at 2.0 A/dm^2.The degradation mechanism was investigated by H-type cell experiment and infrared spectroscopy,from which it was concluded that hypochlorous acid was formed after the chlorine produced on the anode surface dissolved in water.The chromophores in rhodamine B molecules can be destroyed by the oxidative effect of the hypochlorite species,and rhodamine B molecule can be decomposed into organic species with lower molecular weight.Due to their poor solubility in water,the resulting organic species with lower molecular weight can be separated from the wastewater by the air flotation effect resulting from the production of chlorine and hydrogen at the anode and cathode respectively,which contributes to the reduction in COD and decolorization of the wastewater.