Surface Chemical Properties and Micellization of Disodium Hexadecyl Diphenyl Ether Disulfonate in Aqueous Solution

摘要

The surface tension of disodium hexadecyl diphenyl ether disulfonate (C-16-MADS) was measured at different NaCl concentrations (0.00-0.50 mol L-1) and temperatures (298.0-318.0 K) using the drop-volume method. The results show that, with increasing temperature, the critical micelle concentration (CMC) of C-16-MADS increases slightly, but the maximum surface adsorption capacity (I" (max)) at the air-water interface decreases. When the concentration of NaCl was increased from 0.00 to 0.50 mol L-1, the CMC of C-16-MADS decreased from 1.45 x 10(-4) to 4.10 x 10(-5) mol L-1, but the surface tension at the CMC (gamma (cmc)) was not affected. When the concentration of NaCl was increased at 298.0 and 303.0 K, the I" (max) of C-16-MADS increased. When the temperature was increased from 308.0 to 318.0 K, the surface excess concentration (I" (max)) of C-16-MADS abnormally decreased from 2.26 to 1.41 mu mol m(-2) with increasing NaCl concentration. The micellization free energy () decreased from -63.98 to -76.20 kJ mol(-1) with increase of temperature and NaCl concentration. The micellar aggregation number (N (m)) of disodium hexadecyl diphenyl ether disulfonate (C-16-MADS) was determined using the molecule fluorescence probe method with pyrene as probe and benzophenone as quencher. The results show that an appropriate N (m) could be measured only at surfactant concentration above the CMC. The N (m) increased with an increase in C-16-MADS concentration, but the micropolarity in the micelle nucleus decreased. The temperature had little effect on N (m). Compared with typical single hydrophilic headgroup surfactants, aggregates of C-16-MADS exhibit different properties.