Effect of surfactant on evaporation of water

Abstract

The effect of surfactants on the evaporation of water was studied. Two different surfactants, cationic cetyltrimethylammonium Bromide (CTAB) and anionic Sodium Lauryl Sulphate (SLS) were used for this study. Experiments were carried out for different concentrations of CTAB and
SLS. Water loss was found to decrease in presence of surfactants and with increasing the concentration of surfactant. Water loss was comparatively less in the presence of the cationic surfactant CTAB than in case of the anionic surfactant SLS. The effect of electrolyte (NaCl) on evaporation in the presence of both surfactants was also studied and the results show in the presence of electrolytes the evaporation increases compare to the pure surfactant solution. The evaporation of the water is totally depends on the packing of the monomer surfactant molecules at the air-water interface, so the evaporation is decreases in the surfactant solution as monomer
surfactant molecules adsorbed in the air-water interface which creates an extra resistance to evaporation.
Key words: Evaporation, surfactant, electrolyte, critical micellar concentration (CMC)