辉光放电电解等离子体降解水体中的亚甲基蓝

Degradation of methylene blue in aqueous solution by glow discharge electrolysis plasma

用辉光放电电解等离子体(GDEP)技术对模拟染料废水亚甲基蓝(MB)的降解过程进行了研究.通过紫外光谱(UV)分析了放电电压、催化剂对其脱色率的影响,用电导率仪和酸度计测定了降解液的电导率和pH值的变化.结果表明,在最佳电压为600V和放电120min时,可使200mL 20mg·L-1的MB的脱色率达到95.40%,脱色降解过程符合动力学一级反应的特征;降解过程中溶液的最大吸收波长发生蓝移,溶液的电导率先迅速增大后逐渐减小,溶液的pH值先减小后存在增大的趋势,说明在放电过程中产生了大量带电离子及酸性中间产物;Fe2+和Fe3+对MB的降解有催化作用,5min时可使MB的脱色率分别达到95.61%和93.16%;羟基自由基(·OH)对MB的降解起关键作用.

Degradation of methylene blue（MB）solutions has been investigated by glow discharge electrolysis plasma（GDEP）.The effects of applied voltage and catalyst on the discoloration rate are detected using ultraviolet（UV）absorption spectra.The conductivity and pH of MB solution in the degradation process are also recorded by conductivity meter and acidity meter.The results show that the discoloration rate of 20 mg·L-1 MB is up to 95.4% after treating 120 min in 600 V.The degradation process follows the pseudo-first order kinetics.The maximum absorption wavelength of MB solution in664 nm is produced blue shift in the process of degradation.The conductivity of degradation solution increases first and then reduces;however,the pH of the solution reduces first and then increases.All these indicate that a large number of charged ions and acidic substance are produced during the discharge process.Fe2＋and Fe3＋have certain catalytic effect for the degradation of MB.In the presence of Fe2＋and Fe3＋,the decolorization rate of MB within 5min can reach 95.61%and 93.16%,respectively.Hydroxyl radical（·OH）may play a major role for the degradation of MB in the discharge process.