Influences of the concentration and the molar ratio of mixed surfactants on the performance of vesicle pseudostationary phase

Abstract

In our previous work, it was found that the vesicles were formed spontaneously by mixing octyltriethylammonium bromide (C NE Br) with sodium dodecyl benzene sulfonate (SDBS), and the vesicles have been developed as a pseudostationary phase (PSP) in EKC. In the present work, the effects of the concentration and the molar ratio of cationic to anionic surfactant on the vesicle properties and the performances of vesicle PSP in EKC have been investigated. The aggregates at all mixing ratio were negatively charged regardless of which surfactant surplus. As C NE Br proportion increased, the microviscosity of the vesicle became larger. With the increase in the total surfactant concentration, the migration time window broadened at the molar ratio of C NE Br to SDBS of 3:7. Unexpectedly, the window became narrowed at molar ratio of 5:5 and 6:4. However, the methylene selectivity of vesicle PSP at all above-mentioned molar ratios enhanced as the total surfactant concentration increased, no matter whether the migration time window enlarged or narrowed. It implied that the vesicle PSP at molar ratio of 5:5 and 6:4 made it possible to obtain a better separation in a shorter time. When the total surfactant concentration was fixed at 20 mM, the methylene selectivity of the vesicle PSP of molar ratio of 5:5 was comparable to that of 3:7, but the migration time shortened by a half.

Adsorption Characteristics of Ionic Surfactants on Anthracite Surface: A Combined Experimental and Modeling Study

“…At room temperature, the critical micelle concentrations (CMC) of SDBS are about 2.30 mmol/L, and the STAC is about 3.20 mmol/L [31][32][33]. To ensure the sufficient adsorption of surfactants on the surface of anthracite [34][35][36][37], the concentrations of the two surfactants selected in this experiment were both 2000 mg/L, the molar concentration of SDBS was 5.7394 mmol/L, and the molar concentration of STAC was 5.7463 mmol/L, which were higher than their respective CMC.…”