| Abstract: | Abstract The present study has been undertaken to observe the relative efficiency of removal of metanil yellow from its aqueous solution by using different adsorbents like fly ash and activated carbon produced from different sources i.e. coconut shell, mehagani saw dust, and rice husk. It has also been observed that the rate of adsorption is highly dependent on contact time, adsorbent dose, pH, and initial concentration of the dyestuff. Rate of removal has been observed to increase with increasing contact time and adsorbent dose but with decreasing initial concentration. Higher removal has been observed generally in acidic range. Adsorptions by the adsorbents under investigation follow the Freundlich and Langmuir isotherm models where Freundlich and Langmuir constants have also been determined at different temperatures. Isotherms have been used to obtain the thermodynamic parameters like free energy, enthalpy and entropy of adsorption. Kinetic studies showed that all the adsorbents follow first order adsorption rate model with respect to the dye solution concentration. Various kinetic parameters such as first order adsorption rate constant, mass‐transfer co‐efficient, pore‐diffusion constant, and activation energy of adsorption were evaluated to establish the mechanism. Adsorption processes were found to be endothermic, spontaneous, and pore‐diffusion controlled for all the adsorbents. Among the adsorbents used in this study, activated carbon produced from mehagani saw dust has been found to be the most effective, which remove almost 100% metanil yellow from its 1000 ppm aqueous solution. |
