A glassy polyvinyl alcohol/silica gel hybrid composite for safranin removal: Adsorption, kinetic and thermodynamic studies

The potency of the prepared glassy polyvinyl alcohol/silica gel hybrid composite to remove safranin from aqueous solutions has been explored. The obtained hybrid composite was firstly characterized by FTIR, XRD, SEM, EDX and TGA. Factors affecting the safranin removal process like pH, adsorption time, initial concentration of dye, adsorbent amount and temperature, were fully investigated. The obtained data were treated using four kinetically models and two adsorption isotherm models. Results of kinetic study revealed that the pseudo first order was good in agreement with experimental results rather than pseudo second order, Weber and Morris Intra- particle model and Elovich model. The equilibrium adsorption isotherms revealed that Langmuir model was suitable and well compatible with experimental results than Freundlich one. The maximum adsorption capacities at 293, 303 and 318 K were 9.5, 11 and 12.5 mg g−1, respectively. Thermodynamic studies surmised that the removal process was spontaneous, endothermic and physisorption controlled (ΔHo = 17.48 kJ mol−1).