Adsorption of Eosin Dye from Aqueous Solution Using Groundnut Hull–Based Activated Carbon:Kinetic, Equilibrium, and Thermodynamic Studies

摘要

This article reports the use of activated carbon prepared from groundnut hulls (GHAC) in the adsorption ofneosin dye from aqueous solution in batch process. The prepared GHAC was characterized using Brunauer,nEmmett and Teller (BET), Fourier transform infrared, and scanning electron microscopy. Operational parametersnsuch as agitation time, initial dye concentration, pH, and effect of temperature were studied. Equilibrium timenfor the adsorption process was attained in 6 h. Adsorption isotherms used to test the adsorption data werenLangmuir, Freundlich, Temkin, and Dubinin-Radushkevich (D-R) isotherms. Adsorption equilibrium data werenbest described by these isotherms in the following order: Temkin > Langmuir > Freundlich > D-R. Kinetic datanwere fit using pseudo-first- and second-order kinetic models. Adsorption of eosin dye onto GHAC was bestndescribed by the pseudo-second-order kinetic model. Thermodynamic parameters such as DG0, DH0, and DS0 ofnthe adsorption process were determined; the adsorption process was feasible, endothermic, and spontaneousnwith increased randomness at the solid–solution interface. The mean energy of adsorption ( < 8 kJ/mol) obtainednfrom D-R isotherm showed that the reaction followed a physisorption mechanism. Regeneration and reusabilitynof GHAC were assessed for four successive adsorption–desorption cycles and was found to retain its adsorptivencapacity as high as 98%. This study has shown that GHAC is a good adsorbent in the treatment of eosin dyenfrom aqueous solution.