Determination of equilibrium, kinetic and thermodynamic parameters for the adsorption of Brilliant Green dye from aqueous solutions onto eggshell powder
26-31The removal of the Brilliant Green (BG) dye using hen eggshell powder (abundantly
available and a total waste material) has been explored. Adsorption studies for
the dye removal by eggshell powder has been carried out under varying
experimental conditions of adsorbent dose, temperature, contact time, initial dye
concentration and pH. The equilibrium
data has been studied using the Langmuir isotherm equation. Monolayer
adsorption capacity of hen eggshell powder for BG dye is found to be 44.7 mg/g,
34.23 mg/g and 30.23 mg/g at temperatures 303, 313 and 323 K respectively. The
kinetic study on BG suggests that the adsorption follows the pseudo-second order
kinetics. Adsorption follows both surface adsorption and intra-particle
diffusion mechanisms. The Arrhenius energy of activation observed from the
experimental data is found to
be -15.88 kJ/mol which suggests that the energy barriers are absent
in the adsorption process and the reaction is exothermic. The thermodynamic
study on BG reveals that the reaction is spontaneous, exothermic and proceeds
with decreased randomness at the solid-solution interface as the entropy change
(-19.08 J/mol/K) is negative