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A promising photolysis based technology to dechlorinate polychlorinated biphenyls (PCBs), extracted from soils, in alkaline isopropanol (IPA) as reaction medium has been proposed. To be marketable the impact of co-contaminants extracted along with the PCBs, on the photodechiorination process needs investigation. In this paper the effectiveness of the photodeclorination process on PCBs extracted from samples of a representative soil containing co-contaminants is reported. The pholodechl ori nation or PCBs extracted from weathered soils showed promising results of more than 76% dechlorination within the first hour of UV irradiation. Nearly complete dechlorination (96%) was achieved after 2 h of UV irradiation. To provide quantitative controlled appraisal of the effect of co-contaminants and explanation of the effects, dechlorination of neat Aroclor 1254 in the presence of the common co-contaminant, transformer oil, was evaluated. Further, the effect of transformer oil on some of the individual PCB congeners in the Aroclor mixture was also studied. The difference in the maximum percentage dechlorination of PCBs with and without transformer oil is 15%. Key words: PCBs, extraction, dechlorination, 2-propanol, transformer oil, co-contaminants. Une technologie prometteuse basee sur la photolyse est proposee pour dechlorer les BPC extraits des sols dans un milieu de reaction compose d'alcool isopropylique alcalin. Afin d'etre commercialisable, il faut examiner l'impact des co-contaminants extraits avec les BPC lors du processus de photo-dechloration. Dans eel article, l'efficacite du processus de photo-dechloralion sur les BPC extraits d'echantillons d'un sol representatif contenant des co-contaminants est presentee. La photo-chloration des BPC extrails de sols alleres a monlre des resultals de dechloraiion prometteurs de plus de 76% dans la premiere heure de rayonnement UV. Une dechloration presque complete (96 %) a ete realisee apres 2 heures de rayonnement UV. Pour fournir une evaluation quantitative controlee de l'effet des co-contaminants et I'explication des effets. la dechloration d'Aroclor 1254 pur en presence du co-contaminant commun, de l'huile de transformateur, a ete evaluee. De plus, l'effet de l'huile de transformateur sur certains des congeneres individuels des BPC dans le melange d'Aroclor a egalement ete etudie. La difference dans le pourcentage maximum de dechloration des BPC avec et sans huile de transformateur est de 15%. Mots-cles: BPC. extraction, dechloration. alcool isopropylique. huile de transformateur, co-contaminants. [Traduit par la Redaction], Introduction Recent successes on the dechlorination of polychlorinated biphenyls (PCBs) using UV, has opened possibilities of applying this technique to remediate PCB contaminated soils and sediments. The dechlorination of PCBs [...]

In this study, a sulfoxide residue bonded silica stationary phase was prepared for the separation of polychlorinated biphenyls (PCBs) from mineral oils, and its properties were investigated. Organic sulfide was attached to a silica surface by an amide bond, and the bonded sulfide residues were oxidized to sulfoxide with hydrogen peroxide to afford sulfoxide and sulfone residues bonded to the stationary phases (0.84 and 0.63 mmol of sulfur bonded per gram, respectively). The oxidation states of sulfur atoms bonded on the stationary phases could be determined using high-resolution X-ray fluorescence spectra. The modified stationary phases, especially sulfoxide-bonded one, separated PCBs from mineral oils (paraffin-based transformer oils) more efficiently than aminopropyl silica or other polar stationary phases that have been used for the cleanup of PCBs. The chromatographic parameters for an aliphatic hydrocarbon (eicosane) and some PCB congeners indicated strong retention of highly chlorinated biphenyls by the sulfoxide-bonded silica compared with the aminopropyl silica. A cleanup procedure was established for simple determination of PCBs in mineral oil samples using the sulfoxide-bonded silica packed column fractonation. The analytical method was validated using a certified reference material and a PCB-fortified transformer oil sample.

A novel pilot-scale flow through photoreactor has been designed with the intent to apply it in the field. The photoreactor uses a new plastic coil, instead of the conventional quartz tube. The photoreactor consists of six ultraviolet (UV) lamps with five around the coil and one at the center. Laboratory investigations were conducted using the photoreactor to treat neat Aroclor 1254 in alkaline isopropanol (IPA). The photoreaction is fast and efficient, even though the UV transmittances of the three plastic tubes investigated were lower than that of quartz. The reaction kinetics of the practical mixtures are explored. An analysis of five different constituent congeners of Aroclor 1254 indicated that higher congeners dechlorinate producing some of the lower ones, which are subsequently dechlorinated. The dechlorination of Aroclor 1254 was faster when water was added to the alkaline IPA-Aroclor solution. DOI: 10.1061/(ASCE)0733-9372(2007)133:6(646) CE Database subject headings: PCB; Ultraviolet radiation; Degradation; Reactors.

The complete genome sequence of Rhodococcus sp. strain RHA1 is analyzed in the biphenyl pathway (BPH) and a microarray with probe for 8,313 genes is developed and employed. The analysis suggests that up to 22 enzymes, including 8 newly identified ones, may function in the BPH pathway of RHA1.

Assays for both quantitative and qualitative analyses are developed to assess sediment microcosm enrichments that reductively dechlorinated polychlorinated biphenyls (PCBs). The results indicate that individual species within Chloroflexi displays a limited range of congener specificities and that a relatively diverse community of species within a deeply branching group of Chloroflexi with complementary congener specificities is likely required for the reductive dechlorination of different PCBs congeners in the environment.

Polychlorethylene radicals, anions, and radical anions are potential intermediates in the reduction of polychlorinated ethylenes. Ab initio electronic structure methods are used to calculate the thermochemical properties of 37 different polychloroethylenyl radicals, anions, and radical anion complexes for characterizing reduction mechanisms of polychlorinated ethylenes.

The hypothesis of global fractionation predicts changes in the composition of persistent organic pollutant mixtures with latitude. Polychlorinated biphenyls (PCBs) have played an important role in the derivation of this hypothesis.

Global reactivity and local selectivity profiles of 2,2',5,5'-tetrachlorobiphenyl was calculated using the B3LYP/6-31G method in gas and solution phases. It is seen that both global and local electrophilicity helps in understanding the overall toxic nature of the system.

Mechanical and dielectric spectroscopies were carried out on PCB54 and PS590, two glass-forming liquids with nearly identical glass temperatures. Several anomalies were observed in the dynamics of both the neat materials and their blend.

The isolation from sediment of an ultramicrobacterium, strain DF-1, that is capable of dechlorinating polychlorinated biphenyls (PCBs) is reported.

The positive and practical changes taking place in bacterial communities of a polychlorinated biphenyl (PCB)-contaminated soil after introducing host plant for rhizoremediation is studied. Results conclude that bacterial community was different from its parental community during the development of the Salix viminalis sp. root system.

A sequence-based approach is developed for the fast isolation and characterization of class II aryl-hydroxylating dioxygenase activities. The results have shown that this approach can be applied to obtain novel dioxygenase specificities that complement or supplement known ones.

Anaerobic bacteria of the Dehalococcoides group derived from sediment of the Housatonic River have simultaneously dechlorinated 64 polychlorinated biphenyl (PCB) congeners carrying four to nine chlorines in Aroclor 1260 in the sediment-free JN cultures. The identification of Dehalococcoides organisms as catalysts of extensive Aroclor 1260 dechlorination has provided opportunities for studying the organisms' ecophysiology and design molecular tools required for bioremediation applications.

Burkholderia xenovarans strain LB400, which possesses the biphenyl pathway, was engineered to contain the oxygenolytic ortho dehalogenation operon, allowing it to grow on 2-chlorobenzoate and to completely mineralize 2-chlorobiphenyl. Inoculation at different cell densities did not affect the extent of polychlorinated biphenyl biodegradation.

A sediment-free anaerobic enrichment cultures that dechorinate a broad spectrum of highly chlorinated polychlorinated biphenyls (PCBs) was developed. The development of highly enriched, robust, stable, sediment-free cultures that extensively dechlorinate a highly chlorinated PCB mixture is a major and unprecedented breakthrough in the field.

The abundance, identities, and degradation abilities of indigenous polychlorinated biphenyl (PCB)-degrading bacteria associated with five species of mature trees growing naturally in a contaminated site were investigated to identify plants that enhance the microbial PCB degradation potential in soil. The apparent association of certain plant species with increased abundance of indigenous PCB degraders including with organisms with outstanding degradation abilities, through the root zone supports the notion that biostimulation through rhizomediation is a promising strategy for enhancing PCB degradation.

The hypothesis of global fractionation predicts changes in the composition of persistent organic pollutant mixtures with latitude. Polychlorinated biphenyls (PCBs) have played an important role in the derivation of this hypothesis.

Polychlorinated dibenzo-p-dioxins (PCDDs) are one of the most intensively studied chemical pollutants. The intramolecular chlorine repulsion effects in PCDDs are systematically analyzed by using isodesmic reactions.