Evaluation of thermodynamic parameters for the activated charcoal-phenobarbitone adsorption system.

Poisoning with phenobarbitone is common occurrence all over the world. The removal efficiency of this drug by activated charcoal has been investigated. In vitro experiments were performed to determine the extent and duration of adsorption of phenobarbitone onto activated charcoal in solutions of various pH and at different temperatures. The results of studies supported the evidence of the effectiveness of charcoal as an adsorbent for phenobarbitone. With increasing the amount of activated charcoal, adsorption increases and was almost complete with 60 minutes. The adsorption of phenobarbitone onto activated charcoal was almost independent of pH. Thermodynamic parameters like change of enthalpy (delta H) and free energy (delta G) of the process were evaluated. The adsorption process follows the Langmuir isotherm model where b and n, Langmuir constants were also determined at different temperature and pH. A mathematical model has been established based on experimental data for adsorption of drug onto activated charcoal.