ISOTHERM, KINETICS AND THERMODYNAMICS OF SYNTHETIC DYES ADSORPTION ONTO ACTIVATED CHARCOAL MADE FROM OIL PALM MIDRIB

In this report, we prepared activated charcoal from oil palm midrib and used it as an adsorbent to decolorizeReactive Red and Direct Green as synthetic dyes in the sample solution. The response of various experiments conditions, such as contact time, solution pH, temperature, the weight of adsorbent, and concentration of dyes, on adsorption of synthetic dyes, were evaluated along with the analysis of isotherms, kinetics, and thermodynamics adsorption parameters. At equilibrium, adsorption of dyes onto activated charcoal fitted well to Freundlich model giving coefficients of correlation R ≥ 0.9. At optimum conditions, capacities of adsorption for Reactive Red 120 and Direct Green 26 were 151 and 116 mg/g, respectively. The kinetics study suggested that dyes adsorption onto activated charcoal followed the model of pseudo-second-order with thermodynamic parameters of ∆G°, ∆H°, and ∆S° were -0.21 to -3.93 kJ/mol, -30.15 to -36.12 kJ/mol, and 0.003 J/mol.K, respectively. Based on the experiments, we conclude that dyes adsorption was exothermic, spontaneous and an increase in the system entropy. The results of FT-IR analysis indicated the involvement of various functional groups, including hydroxyl and amine groups. This study emphasizes the potential of oil palm waste as an alternative low-cost adsorbent for the removal of dyes.