m-4-m型Gemini表面活性剂对铂电极上亚甲蓝吸附溶出伏安行为的影响

在0.050 mol·L-1磷酸盐缓冲溶液(PBS)中(pH=6.4), 亚甲蓝(MB)在铂电极上于-0.2 V产生一对不明显的伏安峰. 当向溶液中加入阳离子型Gemini表面活性剂Br-C16H33N+(CH3)2-C4H8-N+(CH3)2C16H33Br-, Br-C12H25N+(CH3)2-C4H8-N+(CH3)2C12H25Br-或Br-C8H17N+(CH3)2-C4H8-N+(CH3)2C8H17Br-后, 亚甲蓝的氧化峰显著增高, 还原峰降低, 氧化还原峰峰电位均正移, 这和表面活性剂与MB在电极表面的协同吸附有关. 联接基团相同的Gemini表面活性剂, 其影响程度随烷基链的增长而逐渐增强. 增大表面活性剂的浓度, MB的氧化峰先升高后缓慢降低. 如当Br-C16H33N+(CH3)2-C4H8-N+(CH3)2C16H33Br-的浓度为15 μmol·L-1 时, 5 μmol·L-1 MB的氧化峰峰电流达到最大值. 此外,溶液pH值和富集电位等对MB及表面活性剂的吸附亦有影响.

Influence of m-4-m Structured Gemini Surfactants on the Adsorption-Stripping Voltammetric Behavior of Methylene Blue on a Platinum Electrode

In 0.050 mol·L-1 phosphate buffer solution (pH=6.4), methylene blue (MB) exhibited a pair of small peaks at about -0.2 V on a platinum electrode. In the presence of m-4-m structured Gemini surfactants, such as Br-C16H33N+-(CH3)2-C4H8-N+(CH3)2C16H33Br-, Br -C12H25N+(CH3)2-C4H8-N+(CH3)2C12H25Br-, and Br -C8H17N+(CH3)2-C4H8-N+-(CH3)2C8H17Br-, the anodic peak of MB grewrapidly but the cathodic peak decreased, and the peak potentials moved in positive direction due to the associated adsorption of Gemini surfactants and MB on the electrode surface. The influence of Gemini surfactants increased with their length of alkyl chain growing. When their concentrations were enhanced, the anodic peak increased firstly and then lowered. For Br-C16H33N+(CH3)2-C4H8-N+(CH3)2C16H33Br- the anodic peak of 5 μmol·L-1 MB achieved the maximum when its concentration was 15 μmol·L-1. In addition, solution pH and accumulation potential also showed effect on their adsorption behavior.