辉光放电电解等离子体降解水体中的罗丹明B

用辉光放电电解等离子体(GDEP)对模拟染料废水罗丹明B(RhB)的降解过程进行了研究.通过发射光谱法测定了GDEP产生的活性粒子,采用紫外光谱分析了放电电压、溶液浓度、pH、Fe~(2+)等对RhB脱色率的影响,并用电导率仪和酸度计测定了降解过程中溶液的电导率和pH的变化,同时结合红外光谱粗略探讨了降解机理.结果表明,在最佳电压为600 V和放电60 min时,200 m L 20 mg·L~(-1)RhB的脱色率可达95.4%,降解过程符合动力学准一级反应;降解过程中溶液的电导率先增大后减小,溶液的pH呈现先减小后增大的趋势,说明在放电过程中产生了大量带电离子及酸性中间产物;加入0.03 mmol的Fe~(2+)对RhB的降解有催化作用,在pH=3.19条件下,放电5 min可使RhB的脱色率达到98.3%;羟基自由基(·OH)对RhB的降解起关键作用.

Degradation of Rhodamine B in aqueous solution by glow discharge electrolysis plasma

Degradation of Rhodamine B (RhB) solutions was carried out by using glow discharge electrolysis plasma (GDEP). The active species such as ·OH, ·H and ·O was detected by emission spectrum of GDEP. The effects of applied voltage, solution concentration, pH and Fe²⁺ on the discoloration rate were investigated using ultraviolet spectra. The conductivity and pH of RhB solution in the degradation process were also recorded by conductivity meter and acidity meter. In addition, the preliminary degradation mechanism of RhB was discussed by FT-IR. The results show that the discoloration ratio of RhB is up to 95.4% after treating 60 min in 600 V. The degradation process follows the pseudo-first order kinetics. The conductivity of degradation solution increases first and then decreases, however, the pH of the solution decreases first and then increases. All these indicate that a large number of charged ions and acidic substance are produced during the discharge process. Fe²⁺ has promising catalytic effect for the degradation of RhB. In the presence of Fe²⁺, the decolorization ratio of RhB within 5 min at pH=3.19 can reach 98.3%. Hydroxyl radical (·OH) plays a major role for the degradation of RhB.