Soil-catalyzed polymerization of phenolics in polluted waters.

Some biotic and abiotic soil components are able to catalyze phenol oxidation, producing water-insoluble polymers. In phenol-polluted water bodies, this phenomenon could be exploited to prevent phenol dispersion. The reaction kinetics of phenol polymerization catalyzed by soil samples drawn from unsaturated and aquifer layers was measured in slurry, aerated batch reactors. Catechol was used as a model phenol. The observed catalytic activity is essentially abiotic and can be attributed to inorganic soil components. The rate of phenol removal is first-order with respect to both catechol and soil concentration. Soil activity towards other phenolic compounds was tested, as well. Diphenols show the highest reactivity. Comparisons were performed with the enzymatic activity of phenol oxidases-containing mushroom tissues whose use has been envisaged in the treatment of phenol-polluted waters. The use of phenol oxidases can complement the intrinsic activity of soil for the removal of recalcitrant phenols.