The interaction of sodium dodecyl sulfonate and petroleum sulfonate with nonionic surfactants (Triton X-100, Triton X-114)

We have investigated the synergistic interaction between sodium dodecyl sulfonate (AS) and two nonionic surfactants [Triton X-100 (TX-100), Triton X-114 (TX-114)] in 0.1 M NaCl. Surface tension results show that a synergism exists in mixed micelle formation and surface excess concentration increases as at the specific α1 values (the net mole fraction of component 1) for these binary systems as compared with the single surfactant system. The strength of the interaction of AS with the nonionic surfactant in two systems obeys the following order: AS–TX-100>As–TX-114. As a practical consideration, we try to apply RST (regular solution theory) to treating sodium petroleum sulfonate (SPS)–TX-100 systems. The experimental results indicate that the interaction of SPS with nonionic surfactants is much stronger than that of AS with nonionic surfactants. In addition, electron spin resonance (ESR) results are very consistent with predictions made by RST, and reveal the formation of mixed micelles in As–TX-100 and As–TX-114 systems.