THERMODYNAMIC STUDY OF ADSORPTION OF PHENOLIC COMPOUNDS ON A PHENOL HYDROXYL MODIFIED POLYSTYRENE

Equilibrium data for the adsorption of phenolic compounds, phenol, p-cresol, p-chlorophenol and p-nitrophenol, from aqueous solutions by Amberlite XAD-4 polymeric adsorbent and a water-compatible phenolic hydroxyl modified polystyrene adsorbent (AM-1) within temperature range of 283-323K had been obtained and were correlated with a Freundlich-type of isotherm equation. The equilibrium constants KF and n were obtained. The capacities of equilibrium adsorption of AM-1for all four phenolic compounds increased around 20% over that of Amberlite XAD-4, which may be contributed to phenol hydroxyl group on the surface and the unusual pore distribution. At their dilute solution, the equilibrium adsorption capacities of AM-1for phenol increased about 62% over that of Amberlite XAD-4, suggesting an advantage of AM-1 over Amberlite XAD-4 in the collection of phenol. Estimations of the isosteric enthalpy of adsorption, free energy, and entropy of adsorption are reported and, the adsorption behaviors are reasonably interpreted.