Thermodynamics aspect of tannin sorption on polymeric adsorbents

Hypercrosslinked polydivinylbenzene and gel type poly(styrene- co-divinylbenzene) post-crosslinked with isocyanuric acid and macroporous crosslinked poly ( N-vinyl acetamide) adsorbent were prepared for adsorbing tannin from aqueous. The sorption isotherms were measured and the isosteric enthalpy was quantitatively correlated with the fractional loading for the tannin sorption onto the three polymeric adsorbents. Surface energetic heterogeneity was observed for the three adsorbents and described with the functions of isosteric enthalpy. The causative factors of the surface heterogeneity of the adsorbents and the mechanism of tannin sorption onto the adsorbents from aqueous were discussed. It was suggested that multiply hydrogen bonding, π–π interaction and hydrophobic interaction were involved in tannin adsorption onto the polymeric adsorbents.