Studies on Dynamic Surface Tension of an Outstanding Microemulsifier in Supercritical CO₂ and Its Wetting Performance

Abstract

Dodecyl polyoxyethylene(4) polyoxypropylene(5) ether (LS45) is an outstanding microemulsifier in supercritical CO₂. The dynamic surface tension (DST) of this nonionic surfactant was investigated by using the maximum bubble pressure instrument. The effects of concentration and temperature on DST parameters (n, t_i, t*, t_m, and R_1/2) and its adsorption mechanism were discussed by Rosen's empirical equation and the asymptotic Ward and Tordai equation for the LS45 solution system. Finally, the parameters at 1 s related to Draves's wetting performance, pC_20(1s), C_1s (i)*, and C_1s*, analyzed. The results showed that were with increase of bulk concentration and temperature, dynamic surface activity increased. Parameters at 1 s indicated that LS45 is of high surface activity and a very good wetting agent. One‐second related parameters, C_1s (i)* and C_1s*, are valuable in the treatment of practical applications of surfactants. Optimum wetting can be expected at the concentration of 4.8×10⁻⁴ mol/dm³ for LS45 solution.

Keywords:

• Dynamic surface tension
• wetting parameters
• maximum bubble pressure

Acknowledgment

The authors wish to thank the financial support of the Natural Science Foundation of China (Grant No 30370945) and the Fund Foundation of Guizhou Provincial Governor (Qian No 2001‐6).