Clouding of Triton X-114: The effect of added electrolytes on the cloud point of Triton X-114 in the presence of ionic surfactants

Abstract

Abstract The cloud point-concentration curve of Triton X-114 (TX114) aqueous solutions has been measured and a lower consolute temperature of 11°C at about 0.03 wt.% is obtained. The cloud point-composition curve of mixed surfactants TX114 and TX100 solution (total concentration of 2%) shows a negative deviation from ideal additivity. The cloud point of 1 wt.% TX114 solution is also measured in the presence of the ionic surfactants with or without added electrolytes. The presence of small amounts (1.25 mM) of sodium dodecyl sulfate (SDS) or cetyltrimethylammonium bromide (CTAB) in the system leads to a substantial increase (about 50°C) in the cloud point of TX114 solution. The inorganic electrolytes ( 3 > MgCl 2 > NaCl; while for CTAB-TX114 mixed micellar solution, the polyvalent anions of the added electrolytes are more effective than the univalent anion, the order of decreasing effect is K 3 Fe(CN) 6 > K 2 SO 4 > KNO 3 . In addition, the results indicate that the secondary effect of the electrolytes, i.e. the salting-out effect, should also be considered.