The Influence of Type of Surfactant on Physicochemical Properties of Liquid Soap
In this paper, two different groups of liquid soaps were prepared. The first group of samples consisted of anionic surfactant (SLES), amphoteric surfactant (BETAIN) and nonionic surfactant (DEA). The second set of samples consisted of anionic surfactant and two nonionic surfactants. The aim of this work is to investigate the influence of the type of surfactant as well as the mass fraction of surfactants on the physicochemical properties of liquid soap. The surface tension, electrical conductivity and density for different concentrations of all examined type of surfactants have been determined as well as the critical micelle concentration (CMC). Moreover, the studies have shown that by increasing concentrations of zwitterionic (amphoteric) surfactant, and by decreasing concentration of nonionic surfactant, a mild decrease in pH value and viscosity increase occurred. In contrast, with increasing polyglycoside concentrations and decreasing concentration of DEA, a mild increase in pH but a decrease in viscosity was observed. In order to monitor the stability of the liquid soaps obtained, the appearance, color and odor were observed at three different temperatures at +4°C, room temperature and at + 40°C, in the dark and under UV light during the three months.