| dc.description.abstract | The adsorption of reactive green 19 (RG19) on chitosan beads was studied in batch system. Various experimental parameters were studied, including initial dye concentration (50 - 500 mg/L), contact time, pH of solution (2 - 13) and temperature (25 - 50 °C). The experimental data were analyzed using Langmuir and Freundlich isotherm model. The result showed a better fit to the Langmuir isotherm model, claiming a homogeneous surface of chitosan beads produced. Pseudo-first-order, pseudo-second-order kinetic were used to analyze the kinetic data. It was found that the kinetic data fitted well with the pseudo-second-order kinetic model, which suggest that the adsorption is controlled by the chemisorptions process. Thermodynamic studies were carried out and various thermodynamic parameters, such as Gibbs energy (ΔG°), entalphy change (ΔH°), entrophy change (ΔS°) and activation energy (Ea) were calculated. The results reveal that RG19 has a good affinity towards chitosan beads and the adsorption process was spontaneous and endothermic. Since the low value of Ea and ∆G° indicates that process is more towards physisorption mechanism, it is concluded that the adsorption of RG19 onto chitosan beads are taking the combination route of physical and chemisorptions. | en_US |
