AOT/Triton X-100混合反胶束体系的导电性能

采用聚乙二醇辛基苯基醚(TritonX-100)和二(2-乙基己基)琥珀酸磺酸钠(AOT)双表面活性剂,与正己烷、正己醇和水构成混合反胶束体系;研究了表面活性剂质量比、助表面活性剂含量、水油体积比和温度等因素对反胶束体系导电性能的影响,同时采用循环伏安法研究了K3Fe(CN)6/K4Fe(CN)6在该体系中的电化学行为.结果表明:由两种表面活性剂构成的反胶束体系电导率σ明显大于单一表面活性剂反胶束体系电导率;体系电导率随AOT与TritonX-100的质量比w(w=mAOT∶mTritonX-100)的变化而变化,w为0-0.4时,电导率随w增大而线性增大,之后增加趋势变缓;w=0.96时,σ达到稳定值576μS·cm-1.混合体系电导率随溶水量的增大及温度的上升而提高;而增加助表面活性剂可显著降低体系的电导率.在所研究体系中,Fe(CN)36-/Fe(CN)46-电化学反应对的氧化还原峰电位几乎不随扫描速率变化,峰电位差约为75mV,峰电流的比值约为1,氧化峰电流与扫描速率的平方根成正比,说明K3Fe(CN)6/K4Fe(CN)6在混合反胶束体系中显示出良好的氧化还原可逆性,反应由扩散步骤控制.

Conductivity of AOT/Triton X-100 Mixed Reverse Micelles

Surfactants p-octyl polyethylene glycol phenyl ether (Triton X-100) and bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) were mixed to prepare reverse micelles with n-hexane, n-hexanol, and water. The effects of surfactant mass ratio, concentration of co-surfactant, volume ratio of water to oil, and temperature on the conductivity of the reverse micelles were studied. The electrochemical behavior of potassium ferricyanide (K₃Fe(CN)₆)/potassium ferrocyanide (K₄Fe(CN)₆) in the mixed reverse micelles was investigated by cyclic voltammetry. The results indicate that the conductivity of the mixed reverse micelles is much higher than that of the single surfactant reverse micelles and it changes with the surfactant mass ratio w (w=m_AOT∶m_{Triton X-100}). When w changed from 0 to 0.4, the conductivity σ increased linearly. The conductivity then increased slowly and stabilized at 576 μS·cm^-1 when w was 0.96. Simultaneously, the increase in water content and temperature enhanced the conductivity while the addition of co-surfactant decreased the conductivity obviously. In the mixed micelle system, the redox peak potentials of Fe(CN)^3-₆ /Fe(CN)^4-₆ were almost constant with a change in scan rate, and the redox potential gaps were about 75 mV. Furthermore, the ratio of the redox peak current for all scan rates was close to 1. The oxidation peak current increased linearly with the square root of scan rate. The results indicate that the Fe(CN)^3-₆ /Fe(CN)^4-₆ electrochemical reaction is reversible and is controlled by diffusion in the mixed reverse micelle system.