阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）对磷钨酸(PW12)光催化还原降解偶氮染料直接耐晒黑G的影响

以磷钨酸H3PW12O4（PW12）为光催化剂,异丙醇（IS）作为电子给体,研究阳离子表面活性剂十六烷基三甲基溴化铵（CTAB）对PW12光催化还原降解直接耐晒黑G（DB19）的影响.考察了CTAB浓度、pH值、DB19初始浓度等因素对反应的影响,并采用一级反应动力学对反应过程进行分析.结果表明CTAB增强了PW12对直接耐晒黑G的还原脱色作用,CTAB浓度增加,DB19的光催化脱色速率提高.PW12用量对DB19还原脱色的影响程度和趋势与溶液中CTAB浓度有关,当CTAB浓度为0.10 mmol.L-1时,DB19的脱色速率随PW12用量的增加而增加;CTAB浓度为0.05 mmol.L-1,PW12用量为200 mg.L-1时DB19的脱色速率最快,继续增加反而降低.DB19还原脱色速率随其初始浓度升高而降低.另外,通过循环伏安法和暗反应明确还原态杂多蓝对染料的还原脱色作用,并借助UV-Vis光谱研究DB19、PW12、CTAB之间的相互作用,探索CTAB对PW12/IS光催化还原降解DB19的作用机理.该研究结果表明阳离子表面活性剂CTAB能够增强偶氮染料废水的PW12催化还原脱色处理.

Effect of cationic surfactant CTAB on the photocatalytic reductive degradation of DB19 by phosphatotungstic acid

Effect of cationic surfactant cetyltrimethylammonium bromide(CTAB) on the photoreductive degradation of azo-dye Direct Black 19(DB19) by phosphatotungstic acid(PW12) in the presence of isopropanol as an electron donor was studied.The parameters such as CTAB concentration,solution pH,PW12 dosage,and dye concentration which may influence the photocatalytic degradation were investigated through the kinetic analyses.The obtained results indicated that CTAB accelerated photoreductive decolorization of DB19 by PW12 in the presence of isopropanol.The degradation evidently presented a two-phase kinetics,slow and fast.And first-order rate equation fitted the data reasonably well.The decolorization rate of DB19 was found to increase with CTAB concentration.However,effect of PW12 concentration on decolorization depended on the concentration of CTAB used.The decolorization rate increased successively with the increase of PW12 concentration at 0.10 mmol · L-1 CTAB,while it showed a decrease with the increase of PW12 concentration at 0.05 mmol · L-1 CTAB,which suggested the interactions between PW12 and CTAB.The concentration of DB19 displayed a negative effect on its photocatalytic degradation.In addition,cyclic voltammetry and dark reaction were used to confirm the reductive degradation of DB19 by PW12.UV-Vis spectrum analysis was also employed to study the interaction among catalyst,dye,surfactant,and elucidated the degradation mechanism of DB19.This study imply that the cationic surfactant CTAB can enhance the reductive decolorization of azo-dye wastewater when phosphatotungstic acid is used as photocatalyst with the aid of electron donors.