Phase Behavior of Some Nonionics: Interfacial Tension and HLB at Optimum Conditions

At optimum phase behavior, the hydrophile-lipophile balance (HLBOPB) values were determined for different nonionics and nonionic binary mixtures. The molar concentration of surfactant, in all the investigated systems, was kept constant at 0.04 M/L aqueous phase in presence of 0.5 wt% tetraethylene glycol as co-surfactant and 1.0 wt% NaCl. n-Alkanes, from hexane to hexadecane, were used as oil phases. All experiments were carried out at 25C using water oil ratio, 4:1. The study reveals that the IFTOPB is in inverse proportion to HLBOPB, the lower the IFTOPB, the higher the HLBOPB values for each set of the investigated nonionics. When IFTOPB was plotted against the molecular weight of the investigated nonionic mixtures at a different oil phase alkane carbon number, two linear relations had been developed: the first for the monoalkylated and the second for the dialkylated phenol ethoxylate binary mixtures.