KINETICS OF HALOGENATED ORGANIC-COMPOUND DEGRADATION BY IRON METAL

A combination of new and previously reported data on the kinetics of d ehalogenation by zero-valent iron (Fe-0) has been subjected to an anal ysis of factors effecting contaminant degradation rates. First-order r ate constants (k(obs)) from both batch and column studies vary widely and without meaningful correlation. However, normalization of these da ta to iron surface area concentration yields a specific rate constant (k(SA))that varies by only 1 order of magnitude for individual halocar bons. Correlation analysis using k(SA) reveals that dechlorination is generally more rapid at saturated carbon centers than unsaturated carb ons and that high degrees of halogenation favor rapid reduction. Howev er, new data and additional analysis will be necessary to obtain relia ble quantitative structure-activity relationships. Further generalizat ion of our kinetic model has been obtained by accounting for the conce ntration and saturation of reactive surface sites, but k(SA) is still the most appropriate starting point for design calculations. Represent ative values of k(SA) have been provided for the common chlorinated so lvents.