蓖麻油酸甲酯乙氧基化物水溶液的动态表面张力

用最大气泡压力法分别测定了不同环氧乙烷(EO)加合数(10、12、14、16、20)的蓖麻油酸甲酯乙氧基化物(ECAME)水溶液的动态表面张力(DST)。考察了浓度、温度和无机电解质对DST的影响,探讨了不同浓度时DST参数(动态表面张力特性参数n,平衡时间t^*,曲线最大斜率R_1/2)的变化规律。结果表明,随着EO数由10增加到20,DST不断增大;随着浓度由0.5×10^-5 mol/L增加到10×10^-5 mol/L,n由3.02减小到1.05,t^*值由14.45减小到2.29,R_1/2由0.43增大到6.44,则动态表面活性增大,DST降低;随着温度由25 ℃升高至45 ℃,DST降低;吸附初期DST曲线随无机电解质浓度的增大而升高,吸附后期DST曲线随无机电解质浓度的增大而降低。和常规的脂肪酸甲酯乙氧基化物(FMEE)相比,ECAME的动态表面活性更加优异,这为开拓ECAME的应用指明了新的方向。

Dynamic Surface Tensions of Castor Oil Acid Methyl Ester Ethoxylate Aqueous Solutions

The dynamic surface tensions of different average ethylene oxide(EO) adduct number(10, 12, 14, 16, and 20) of ethoxylated castor oil acid methyl esters(ECAME) were measured by maximum bubble pressure method(MBP). The effect of dynamic surface tension at different concentration, temperature and the presence of inorganic electrolyte were investigated. The dynamic surface tension parameters(EO adduct number n, equilibrium time t^*, maximum slope of curve R_1/2) of different concentration were discussed. The results show that dynamic surface tension increases with the average n increasing from 10 to 20, n decreases from 3.02 to 1.05, t^* decreases from 14.45 to 2.29, and R_1/2 increases from 0.43 to 6.44, while the concentration of ECAME ranges from 0.5×10^-5 to 10×10^-5 mol/L. Therefore, the dynamic surface activity increases and the dynamic surface tension decreases. The dynamic surface tension decreases with the temperature increasing from 25 ℃ to 45 ℃. The initial adsorption dynamic surface tension increases with the increasing of inorganic electrolyte concentration and the late adsorption dynamic surface tension decreases with the increasing of inorganic electrolyte concentration. Comparing with conventional fatty acid methyl ester ethoxylate(FMEE), ECAME has an excellent dynamic surface activity. This indicates a new direction for the application of ECAME.