Adsorption of phenol on polymeric resins: Heat of adsorption

Adsorption equilibrium data was obtained from three polymeric resin adsorbents, Amberlite XAD-4, IRA-96, and Lewatit MP-64, and activated charcoal at operating temperatures of 30°C, 40°C, 50°C, 60°C, and 70°C. The residual liquid phase concentration of phenol was obtained for each of the adsorbents at each operating temperature. The equilibrium data showed activated charcoal to be most effective at adsorption of phenol, followed polymeric resins XAD-4, MP-64, and lastly IRA-96, confirming the results obtained by S. Lyric and Z. Ahmed in 1994. The data also showed that with the exception of activated charcoal, increasing the operating temperature increased the equilibrium liquid phase concentration of phenol, indicating that adsorption effectiveness was reduced.; The Surface Adsorption Potential model, which was mathematically similar to the Freundlich isotherm model; was used to calculate the isosteric heat of adsorption of each of the adsorbents for the adsorption of phenol. The Freundlich isotherm was necessarily used to fit the equilibrium data and the Freundlich parameters obtained from the isotherms, kF and l/n, were used to calculate the adsorption potential parameters. The adsorption potential parameters were used to calculate the heat of adsorption.; According to the adsorption potential model, the isosteric heat of adsorption decreases as the adsorbent surfaces are occupied. This suggests that the adsorption surface is not uniform and that the sites with the highest potential are occupied first, resulting in a decrease of the overall heat of adsorption as the sites become occupied.; At 5 mg/g of adsorbed phenol to amount of adsorbent, the isosteric heats of adsorption for activated charcoal, XAD-4, MP-64, and IRA-96 were 63.71, 36.66, 49.84, and 30.11 kJ/mol respectively. The results show that since the heats of adsorption of polymeric resins are generally less than that of activated charcoal, less energy is required to liberate the phenol from the resins than it does from activated charcoal. As XAD-4 has shown to be effective adsorbent for phenol, it may be a suitable alternative to activated carbon for phenol removal with a thermal regeneration being potentially economically viable.