滑动弧等离子体处理酸性橙Ⅱ废水

Degradation of Acid Orange Ⅱ solution by gas-liquid gliding arc discharge

采用气液两相滑动弧等离子体降解酸性橙Ⅱ,研究了酸性橙Ⅱ的降解动力学及降解机理。结果表明:当电压为10 kV,载气为O2,气体流速为0.4 m3.h-1,废水流量为20 ml.min-1,电极间最窄处距离为3.5 mm,溶液浓度在300 mg.L-1以下时,滑动弧等离子体对酸性橙Ⅱ的降解符合一级动力学规律。检测了纯水放电时H2O2、O3生成量以及OH.的相对量。运用紫外光谱(UV-Vis)、离子色谱(IC)、色谱-质谱联用(GC-MS)等方法,测定出酸性橙Ⅱ的主要降解产物有乙酸、乙二酸、丙二酸、苯酚、3-羟基苯乙酮、萘、苯磺酸、邻苯二甲酸(酐)、β-萘酚等,并依此推测酸性橙Ⅱ的降解机理,即羟基自由基攻击酸性橙Ⅱ分子上与萘环相连的C—N键,导致C—N键的断裂,进而染料脱色矿化。

Acid Orange Ⅱ solution was degraded by gas-liquid gliding arc discharge, and its degradation kinetics and degradation mechanism were studied. The results showed that, when applied voltage was 10 kV, carrier gas was O2, gas flow rate was fixed at 0.4 m^3 · h^-1 , wastewater flow rate was 20 ml · min^-1 , shortest electrode distance was 3.5 mm, solution concentration was not more than 300 mg · L^-1 , the degradation reaction of Acid Orange Ⅱ by gliding arc discharge followed the first-order law. The absolute quantities of H2O2, Oa and the relative quantity of OH · produced by gliding arc discharge in distilled water were measured. The main intermediates were detected during decomposition, such as acetic acid, oxalic acid, malonic acid, phenol, 3-hydroxyhypnone, naphthalene, benzene sulfonic acid, phthalic acid （anhydride）, β-naphthalene etc. by ultraviolet-visible （UV-Vis） spectroscopy, ion chromatograph （IC） and gas chromatograph coupled with mass spectrophotometer （GC-MS） techniques. The possible degradation pathway of Acid Orange Ⅱ was also speculated, that was, hydroxyl radical reacted with the azo linkage-bearing carbon of naphthol-ring, and the C--N cleaved, the azo-dye decolored and mineralized.