2007 Volume 50 Issue 3 Pages 173-181
The detergency of the mixture of dodecyl sulfate (SDS) and hexadecyl trimethylammonium bromide (HTAB) was studied using cotton and polyester fabrics. The critical micelle concentration (cmc) of the mixture of mixing ratio 1 : 1 determined by surface tension method was 1×10-4 mol/dm3. Removal of polystyrene latex particles and sterilization of staphylococcus were examined through SEM observation and culture testing. The effect of the mixing ratio of the surfactants on the detergency was investigated. At mixing ratio of about 1 : 1, the removal efficiency of particles had the maximum, and the minimum surface tension of the solution was achieved. This removal efficiency was lager than that at cmc of SDS and HTAB considerably. Sterilization increased with HTAB mixing ratio in the range of the mixing ratio below 0.5 and it was 100% at HTAB mixing ratio more than 0.6. These results suggested the existence of free HTAB molecules in the mixture. The cmc of the mixture was 1/160 and 1/20 of the one for SDS and HTAB respectively.