苄基十四烷基二甲基氯化铵在汞电极上界面吸附的电化学张力

Interfacial Tension of Electrode/Solution of Tetradecyl Dimethyl Benzyl Ammonium Chloride Adsorbed on Mercury Electrode

采用电化学界面张力测量的方法研究了表面活性剂苄基十四烷基二甲基氯化铵(TDMBA)在Hg电极上的吸附行为.在低浓度范围(0～0.07mmol/L)内,TDMBA在Hg电极上的吸附为单层吸附;而在较高浓度范围(0.10～2.00mmol/L)内,能够形成多层吸附.TDMBA在Hg电极上形成单层吸附时与形成多层吸附时的界面张力随施加电位变化有明显的区别,其临界胶束浓度分别为0.04,0.90mmol/L.在-0.7V电位下,TDMBA分子在其饱和吸附单层上的界面超量的最大值为1.452×10-6mol/m2,并据此计算出TDMBA分子的横截面积(1.143×10-18m2)和分子直径(1.207nm).

The adsorption behavior of tetradecyldimethylbenzylammonium chloride（TDMBA）on a drop of mercury electrode was studied.In the concentrations of 0-0.07mmol/L,TDMBA showed a monolayer adsorption on the mercury electrode,and a multi-layer adsorption was presented in the range of 0.102.00mmol/L.The experimental results showed that there were obvious differences in the interfacial tension-potential curves between the monolayer and multi-layer adsorption processes.The critical micelle concentrations（CMC）of TDMBA for monolayer and multi-layer adsorption are 0.04mmol/L and 0.90mmol/L,respectively.When the potential of working electrode was at-0.7V（vs.Ag/AgCl）,the maximum interface excess of TDMBA adsorbed on its monolayer was 1.452×10-6 mol/m2,and the cross section area and the diameter of TDMBA were calculated to be 1.143×10-18 m2 and 1.207nm,respectively.