ADSORPTION OF FLUORIDE FROM AQUEOUS SOLUTION BY EUCALYPTUS BARK ACTIVATED CARBON: THERMODYNAMIC ANALYSIS

In this experimental study, batch adsorption experiments were implemented to survey the potential of eucalyptus bark activated carbon (EBAC) in the adsorption of fluoride (F-). The studied adsorbent was synthesized using the chemical activation method in the presence of phosphoric acid. The effect of several parameters, e.g., the contact time, the initial F- concentration, and the temperature on the F- adsorption onto the EBAC was investigated under constant values for the pH (6.5) and the adsorbent dosage (2 g/L). The calculation of the standard free energy changes (Delta G(0)), the standard enthalpy change (Delta H-0), and the standard entropy change (Delta S-0) were carried out at different temperatures and initial F- concentrations. The Delta G(0) values were negative and the Delta H-0 values and the Delta S-0 values were positive at all temperatures and concentrations which suggests that the F- adsorption onto the EBAC was a spontaneous and endothermic process.