Desalination and Water Treatment, cilt.259, ss.170-185, 2022 (SCI-Expanded)
© 2022 Desalination Publications. All rights reserved.In this study, monomeric and micellar adsorption of cetyltrimethylammonium bromide (CTAB) and tetradecyltrimethylammonium bromide (TTAB) quaternary ammonium salts were investigated. Parameters that influence the monomeric adsorption process such as pH, adsorbent dosage, contact time, monomeric surfactant concentration and temperature were systematically studied. It was seen that these parameters have been affected the adsorption capacity of clay for CTAB and TTAB. The fit of the adsorption data to the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin isotherm models was also examined. The results reveal that the Langmuir isotherm model was more suitable the equilibrium of adsorption on the clay surface. The monolayer adsorption capacities for both adsorbate were found to be 312.50 and 285.71 mg/g, respectively. Thermodynamic parameters showed that the adsorption process was spontaneous and exothermic. Adsorption enthalpy and entropy changes for both adsorbates were calculated as –10.6 and –6.6 kJ/mol and 18.0 and 14.9 J/mol K, respectively. The kinetic results can be represented by pseudo-second-or-der model implying the stronger interactions between clay surface and surfactant ions. The vari-ation of the micellar adsorption capacity with temperature and initial surfactant concentration revealed the changing in micellar forms. The different behaviors of CTAB and TTAB, which may occur depending on the temperature, show that the chain transfer energy, which varies with the tail length, has a dominant effect on the micellar adsorption.