Transformation of Chlorinated Persistent Organic Pollutants in Groundwater Using Sol-Gel Immobilized Metalloporphyrins

We demonstrate the ability of metalloporphyrins, immobilized in sol-gel matrices, to catalytically reduce chlorinated persistent organic pollutants (CPOP) under conditions pertinent to groundwater systems. A large body of information accumulated over the last two decades indicates that chlorinated organic compounds released to the environment have caused considerable damage to ecosystems and to humans. A particularly major concern is contamination of groundwater sources. An important approach to detoxification of CPOP is based on utilization of metalloporphyrins as electron transfer mediators in dechlorination reduction processes under anaerobic conditions. Previous studies have shown that immobilized transition metal macrocycles, formed by intercalation in layered minerals, have in some cases catalyzed electron-transfer-mediated reactions. Such processes provide insight into reactions that can be expected in natural biogeochemical systems. Preliminary results indicate the existence of a reduction process in such systems. Several pollutants, such as PCE and TCE, were transformed into less toxic, nonchlorinated compounds after their exposure to immobilized metalloporphyrins under reducing conditions.