二氧化钛光解与滑动弧等离子联合降解偶氮染料研究

DEGRADATION OF ACID ORANGEⅡSOLUTION BY GAS-LIQUID PHASE GLIDING ARC DISCHARGE WITH TiO_2 PHOTOCATALYSIS

采用气液两相滑动弧等离子和二氧化钛光降解技术联合处理酸性橙Ⅱ,研究了二氧化钛浓度、气体类型和溶液初始pH值对酸性橙Ⅱ降解率的影响。结果表明:在电压为10kV,频率为50Hz,电极间最窄距离处为3.5mm条件下,对于浓度是300mg/L的酸性橙Ⅱ溶液,二氧化钛浓度为1.0g/L,初始pH值为酸性或碱性,载体为氧气,协同效应明显,更有利于酸性橙Ⅱ降解率的提高。同时检测了纯水放电条件下,二氧化钛的加入对活性粒子H_O_2、O_3和OH·生成量的影响,酸性橙Ⅱ降解率的提高是更多活性粒子作用的结果。用红外光谱和GC-MS对降解产物测试分析,推测酸性橙Ⅱ的可能降解途径,即羟基自由基攻击酸性橙Ⅱ分子上的C-N键,导致C-N键的断裂,染料脱色矿化降解。

The influences of mass concentration of TiO2, carrier gas source and the initial pH value on the degradation efficiency of Acid Orange Ⅱ in the combined application of gas-liquid gliding arc discharge with TiO2 photocatalysis were studied. Experimental results showed that in the fixed applied voltage （ 10 kV）, power frequency （50Hz） and the shortest electrode distance （3.5mm） condition, the optimum degradation rate for 500mg·L^-1 Acid Orange Ⅱ solution could be achieved at the TiO2 concentration of 1.0 g·L^-1 with using oxygen as the carrier gas, and the initial pH value was acidic or basic. The effect of TiO2 concentration on the production of H2O2, O3 and OH· active species was also investigated. The enhancement of Acid Orange Ⅱ degradation rate could be mainly attributed to the increasing amount of the active species. Finally, The possible degradation channel of Acid Orange Ⅱ was proposed through the analysis of the main in- termediates detected by gas chromatograph coupled with mass spectrophotometer （GC-MS） and fourier transform infrared spectroscopy（FTIR） techniques. We concluded that the hydroxyl radicals could react with the azo linkage-bearing carbon of a hydroxy, which led to the cleavage of C-N and the discoloration of azo-dye.