Modeling of experimental data for the adsorption of methyl orange from aqueous solution using a low cost activated carbon prepared from Prosopis juliflora

Abstract

This paper presents the feasibility for the removal of methyl orange (MO) dye from aqueous solution using an activated carbon prepared from Prosopis juliflora bark. Batch adsorption experiments were carried out as a function of pH, contact time, adsorbate concentration, adsorbent dosage and temperature. The commonly applicable isotherms namely Freundlich and Langmuir equations are used for the prediction of isotherm parameters. A comparison of linear least-square method and a trial-and-error non-linear method are examined in Freundlich and Langmuir (Four forms) isotherms. The nature of adsorption isotherm feasibility was evaluated with dimensionless separation factors (RL). The dynamics of adsorption process was analyzed with Lagergren’s Pseudo-first order and Pseudo-second order kinetic equations. Thermodynamic parameters like the change in enthalpy (ΔHo), change in entropy (ΔSo) and change in Gibbs free energy (ΔGo) were evaluated and ΔGo shows a negative value whereas ΔHo shows the positive value indicating that the adsorption process was spontaneous and endothermic in nature. The functional group characterization of the adsorbent was done using Fourier transform infrared spectroscopy (FTIR). The thermal stability of activated carbon was analyzed using Thermo gravimetric analysis (TGA) and Differential thermal analysis (DTA).