Thermodynamics and Adsorption Study of Methyl Orange onto Fired Bricks

In this study, fired bricks (FB) was used as an adsorbent to remove an anionic dye, methyl orange (MO), from an aqueous solution by the batch adsorption technique. Various conditions were evaluated, including initial dye concentration, adsorbent dosage, contact time, solution pH, agitation speed and temperature. The adsorption isotherms of the FB were studied using the Freundlich, Tekman and Langmuir models. The experimental data obtained with FB fits best to the Langmuir isotherm model and exhibited a maximum adsorption capacity (qmax) of 2.3mg/g. The intraparticle diffusion studies revealed that the adsorption rates were not controlled only by the diffusion step. The thermodynamic parameters, such as the changes in enthalpy (H), entropy (S), and Gibbs free energy (G), showed that the adsorption is endothermic, random and nonspontaneous at high temperature. The results indicate that FB adsorbs MO efficiently and could be utilized as a low-cost alternative adsorbent for the removal of anionic dyes in wastewater treatment.