SORPTION OF PHENOL BY SELECTED BIOPOLYMERS - ISOTHERMS, ENERGETICS, AND POLARITY

The behavior of phenol in the terrestrial environment is strongly regulated by its reaction with soil components. We report here on the uptake of phenol by soil minerals (goethite, kaolinite, and montmorillonite) and by organics that may occur naturally in or be added to soil (two lignins, chitin, cellulose, collagen, and activated carbon). Our objectives were to determine the energetics and capacity for their uptake of phenol using batch equilibration, calorimetry, and CPMAS C-13 NMR and to evaluate the relation of organic carbon referenced sorption coefficient (K(oc)) with the polarity of biopolymers. The biopolymers sorbed 2-45-fold more phenol than did the minerals. The K(d) for phenol uptake by lignins with high aromaticity and low polarity were 4-6.5-fold higher than that for chitin and 13-22-fold higher than that for cellulose. Energy released during the formation of a putative donor-acceptor complex on activated carbon was about 30 kJ/mol. Energy released for sorption of phenol by biopolymers ranged from 5 to 20 kJ/mol. The K(oc) of phenol decreased with increasing polarity: (N + O)/C of the biopolymers. We infer that the K(oc) of organic compounds may not be adequately predicted from their K(ow) without considering the nature of organic matter.