Kinetics, Isotherm and Thermodynamic studies of Adsorption of Congo red from aqueous solution onto COCOA Shell Activated Carbon

The adsorption of Congo red (CR) by Cocoa Shell Activated Carbon (CSAC) was investigated by varying the parameters such as agitation time, concentration, adsorbent dosage, pH and temperature. The results showed that as the amount of the adsorbent increased, the percentage of dye removal increased accordingly. Optimum pH value for dye adsorption was determined as similar to 6.0. The adsorption of CSAC was found to be increasing with increase in temperature. Adsorption kinetics was determined by pseudo first order and-pseudo second order models to the experimental data. The results indicated that the pseudo second- order model proving the best description of CR onto CSAC. The experimental adsorption equilibrium data was analyzed by Langmuir, Freundlich and Dubinin-Radushkevich (D-R) adsorption models. Based on correlation coefficient (r(2)) values, equilibrium data found fitted well to the Langmuir isotherm. The thermodynamic parameters like Delta H-o, Delta S degrees and Delta G degrees were measured based on Van 't Hoff's Plot. The thermodynamics of CR-CSAC system indicates endothermic nature of process. The structure and morphological of activated carbon was characterized by SEM analysis.