A thermodynamic and kinetic approach to adsorption of methyl orange from aqueous solution using a low cost activated carbon prepared from Vitis vinifera L.

In this paper, thermodynamic and kinetic parameters of the Methyl Orange adsorption process on active carbon prepared from endemic Vitis vinifera L. grape seeds (AC-VVL) grown in the Tunceli-Elazığ region and % removal of dye from aqueous solutions were evaluated by using a batch system. Experiments were performed as a function of pH (2, 5, 8 and 11), temperature (15 °C, 30 °C and 45 °C) and initial concentration (100, 150, 300 and 1000 mg L−1). The mechanism and characterization of adsorption of dye was analyzed pre-adsorption (AC-VVL) and post-adsorption (AC-VVL+dye) using FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscope) and Brauner Emmet and Teller (BET) analyzer. The activation energy (Ea) was determined as 24.80, 39.15, −22.40 and 61.73 kJ/mol for 100, 150, 300 and 1000 mg L−1, respectively. The Langmuir, Freundlich, Temkin and Harkins Jura isotherms were used to describe the adsorption equilibrium studies at different temperatures. The Freundlich isotherm shows better fit than other isotherms in the temperature range studied. Maximum adsorption occurred at pH 2 and was approximately 79.7 mg/g. The % Recycling Yield was found to be 20% and 9 mg/g with acetone. Thermodynamic parameters like the change in enthalpy (ΔH o), entropy (ΔS o) and Gibbs free energy (ΔG o) were evaluated and the adsorption process was found to be endothermic and spontaneous. The results show that this AC-VVL biomass is an appropriate biosorbent and has specific affinity for removal of Methyl Orange from aqueous solutions.