采用气体扩散电极降解酸性红B研究

STUDY ON DEGRADATION OF ACID RED B USING GAS DIFFUSION ELECTRODE

采用Pt/C气体扩散电极(GDE)为阴极,对酸性红B溶液进行单室电解和双室电解.单室电解中,以GDE为阴极,效果远优于石墨阴极,H2O2生成量为石墨阴极的10倍,在pH=1时,具有最好的处理效果,电解40min,脱色率为78.3%.通过分室电解,对酸性红B的降解机理进行了分析,阳极区为阳极的直接氧化,受pH值、Fe2+和O2的影响较小;气体扩散阴极为通过还原O2生成H2O2,然后分解为羟基自由基,氧化有机物,受pH值,Fe2+,O2的影响较大.当pH=3,Fe2+浓度为50mmol·l-1,空气流量为180L·h-1时,电解80min,阴极区的脱色率为94.2%,COD去除率为66.8%,而阳极区的脱色率为73.3%,COD去除率为56.2%,电流在阳极区和阴极区的利用效率加起来计算的“表观电流效率”达到145.3%.

Acid red B (ARB) solution was electrolyzed in a single-chamber cell and a two-chamber cell using Pt/C gas diffusion electrode (GDE) as cathode. In the single-chamber electrolysis, the treatment effect of gas (diffusion) cathode was much better than that of graphite cathode;and the H_(2)O_(2) yield of gas diffusion (cathode) was 10 times than that of graphite cathode; when the pH was 1 and electrolysis time was 40min, there was best treatment effect, the color removal was 78.3%. The degradation mechanism of ARB was analyzed through the two-chamber electrolysis. The mechanism in the anodic region was the direct oxidation, which was slightly (affected) by pH variation, Fe(II)existence and aeration. In the GDE, O_(2) was reduced to H_(2)O_(2), then (decomposed) to hydroxyl radical that had strong ability to oxidize organic compounds. Meanwhile, indirect (oxidation) in cathodic region was strongly affected by pH variation, Fe(II)existence and aeration. After ARB solution was treated in that condition: pH was 3, \ was 50mmol ·l^(-1), air flow was 180L·h^(-1), for 80min, the color removal and COD removal in the cathodic region, which were 94.2% and 66.8% respectively, was higher than the removal in the anodic region, which were 73.3% and 56.2%. The apparent current efficiency that was the sum of current efficiency in the anodic and cathodic region reached to 145.3%.