Kinetic and Thermodynamic Study of Triton X-100 Removal from Aqueous Solution of Functionalized Mesoporous Silica

In this work, batch adsorption experiments were carried out for the removal of Triton X-100 as a pollute surfactant from aqueous solutions on mesoporous silica as adsorbents. These silica functionalized with organic groups (methyl and amine) were produced from two different silica precursor (sodium silicate and tetraethoxysilane) using sol-gel method. The effects of major variables governing the efficiency of the process such as dosage of mesoporous silica (25-125 mg), temperature (288-318 K), and initial surfactant concentration (15-120 mg/l), were investigated. Equilibrium data were fitted to the Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherm models and isotherm constants were determined. The equilibrium data were best represented by the Langmuir isotherm model. The adsorption kinetic data were analyzed using pseudo-first-order, pseudo-second-order and intra particles diffusion models. It was found that the pseudo-second order kinetic model was the most appropriate model, describing the adsorption kinetics and the intra-particle diffusion is not the only rate limiting mechanism and that some other mechanisms also play an important role. Thermodynamic parameters such as changes in the free energy of adsorption (?