The adsorption behavior of benzoic acid onto a water-compatible hypercrosslinked polymeric adsorbent NJ-8 was compared with that onto macroporous Amberlite XAD-4.This paper focuses on the static ...equilibrium adsorption behaviors,the adsorption thermodynamics and the column dynamic adsorption profiles.Five isotherm models are used to fit the results.This shows that the Freundlich equation can give a perfect fit.The specific surface area of NJ-8 is about as high as that of Amberlite XAD-4,but the adsorbing capacity for benzoic acid on NJ-8 is about 14.9%-64.8% higher than that on Amberlite XAD-4,which is attributed to its microporous mechanism and partial polarity.The negative values of the adsorption enthalpy are indicative of an exothermic process.Both enthalpy and free energy changes of adsorption manifest a physical sorption process.The negative values of the adsorption entropy indicate that adsorption is well consistent with the restricted mobilities and the configurations of the adsorbed molecules on the surface of the studied adsorbents with superficial heterogeneity.Both adsorbents were used in mini-column experiments to demonstrate the higher breakthrough adsorbing capacity of the hypercrosslinked polymeric adsorbent NJ-8 to benzoic acid,as compared with that of Amberlite XAD-4.
PDF
