Evaluation of Thermodynamic Parameters of 2, 4-Dichlorophenoxyacetic Acid (2, 4-D) Adsorption

Thermodynamic parameters of 2, 4-Dichlorophenoxyacetic acid (2, 4-D) adsorption were evaluated by studying the adsorption equilibrium and kinetics of 2, 4-D at different temperatures. Uptake capacity of activated carbon increases with temperature. Langmuir isotherm models were applied to experimental data of 2, 4-D adsorption. Equilibrium data fitted very well to the Langmuir equilibrium model. Adsorbent monolayer capacity Q(0), Langmuir constant a and adsorption rate constant k(a) were evaluated at different temperatures for activated carbon adsorption. The activation energy of adsorption (E-a) was determined using the Arrhenius equation. Using the thermodynamic equilibrium coefficients obtained at different temperatures, the thermodynamic constants of adsorption (Delta G(0), Delta H-0, and Delta S-0) were evaluated. The obtained values of thermodynamic parameters show that the adsorption of 2, 4-D is an endothermic process.