Study on Adsorption and Antirinsing Performances of Alcohol Ether Sulfate/Dodecyl Trimethylammonium Chloride Mixtures on Silica

This study investigated the adsorption and antirinsing performances of sodium alcohol ether sulfate (AEnS), dodecyl trimethylammonium chloride (DTAC), and mixtures of AEnS/DTAC with an equal molar ratio on silica. The adsorption process for individual surfactants was characterized by an initial slow stage, followed by a sharp increase with longer threshold times. In contrast, AEnS/DTAC exhibited a shorter threshold time. Molecular simulation results indicate that the AEnS/DTAC formed a structure wherein positively charged DTAC was close to the silica surface, while negatively charged AEnS resided close to the cation layer of DTAC. This assembly effectively reduced the electrostatic repulsion between AEnS and silica, as well as among DTAC molecules, thereby achieving the highest adsorption rate and adsorption amount. For antirinsing performances, AEnS was quickly washed off, whereas DTAC shows the lowest desorption rate due to their substantial electrostatic attraction toward silica. Notably, the AEnS/DTAC exhibits enhanced antirinsing, confirmed by atomic force microscopy (AFM) results. This research enhances our understanding of surfactant-silica interactions and offers valuable insights for practical applications in oil displacement, mineral flotation, and surface coatings.