Interaction between anionic dye ECAB, Micelle of Triton X-100 in aqueous solution and hemimicelle at solid/liquid interface

Interaction between dye (ECAB), nonionic surfactant (TX-100) micelle in aqu eous solution and TX-100 hemimicelle at solid (SiO2)/liquid interface has b een investigated quantitatively. There are linear relationships between con centrations of free ECAB(C-a), ECAB bound with TX-100 micelles in solution( C-m) and ECAB bound with TX-100 hemimicelles at interface of solid/liquid(C -hm). The slopes of the three straight lines are 0.32 for C(hm)similar to C -a, -1.32 for C(m)similar to C-a and -1.00 for (C-m+C-hm)similar to C-a, re spectively. The linear relationships can be described by three linear equat ions as follows: C-hm=0.32 (C-a-0.88x10(-5)), C-m=4.0x10(-5)-1.33 C-a and C -hm + C-m=3.742x10(-5)-C-a. It is inferred that the interaction between ECA B, TX-100 micelles and TX-100 hemimicelles is essentially partition of ECAB molecules in solution, TX-100 micelles and hemimicelles. The concentration of ECAB bound with TX-100 micelles increased with increasing TX-100 micell ar concentration and TX-100 hemimicelles concentration, but the concentrati on of ECAB bound with TX-100 hemimicelles at solid/liquid interface decreas ed with increasing TX-100 micelles and hemimicelles concentrations. Additio nally, a quantitative method to determine adsorbance of surfactant TX-100 o n silica gel by spectroscopy in coadsorption conditions of dye(ECAB) and TX -100 was proposed.