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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 [...]

Conventional gas chromatography (GC) analysis of hydrocarbons displaying one broad peak provides limited information. Two GC analytical protocols using two-peak and three-peak approaches were developed to investigate transformer oil components and their degradation in soil by hydrogen peroxide. The two-peak method revealed transformer oil to be composed of 27 wt.% F2 fraction and 73 wt.% F3 fraction hydrocarbons. The three-peak method segregated the transformer oil into 40 wt.% light, 40 wt.% medium, and 20 wt.% heavy hydrocarbon fractions. In contrast to reports of success with several classes of lighter hydrocarbons, only limited degradations of transformer oil in soils by 15% and 30% hydrogen peroxide treatment was indicated by conventional one-peak analysis; two-peak analysis showed varying F2 and F3 fraction degradations with F2 fraction degradation being higher; three-peak analysis offered a richer understanding of the relative degradations of light, medium, and heavy fractions. The effect of a low pH environment on the degradation of transformer oil by hydrogen peroxide was evaluated using the three-peak method. It emerged that the degradation of the medium and heavier fractions of transformer oil was higher at pH 2.0. Key words: transformer oil, soil remediation, hydrogen peroxide, gas chromatography. L'analyse conventionnelle par chromatographie gazeuse (CG) des hydrocarbures montrant un large pic chromatographique ne donne que de l'information limitee. Deux protocoles d'analyse par CG utilisant des methodes a deux et a trois pics chromatographiques ont ete mis sur pied afin d'examiner les composantes de l'huile des transformateurs et leur degradation dans le sol en utilisant le peroxyde d'hydrogene. La methode a deux pics chromatographiques a indique que l'huile de transformateur etait composee de 27 % en poids de fraction d'hydrocarbures F2 et de 73 % en poids de fraction F3. La methode a trois pics chromatographiques a divise l'huile de transformateur en 40 % en poids de fraction legere d'hydrocarbures, 40 % en poids de fraction moyenne et 20 % de fraction lourde. Par rapport aux rapports relatant la reussite de l'utilisation de plusieurs classes d'hydrocarbures plus legers, des degradations limitees de l'huile des transformateurs dans les sols par traitement avec 15 et 30 % d'hydroxyde d'hydrogene ont ete determinees par l'analyse a un pic chromatographique. L'analyse a deux pics chromatographiques montrait des degradations variables des fractions F2 et F3, la fraction F2 se degradant mieux. L'analyse a trois pics chromatographiques permettait de mieux comprendre les degradations relatives des fractions legeres, moyennes et lourdes. L'effet d'un environnement a faible pH sur la degradation de l'huile de transformateur par le peroxyde d'hydrogene a ete evalue en utilisant la methode a trois pics chromatographiques. Il a ete decouvert que la degradation des fractions moyennes et lourdes de l'huile de transformateur etait meilleure a un pH de 2.0. Mots-cles : huile de transformateur, restauration des sols, peroxyde d'hydrogene, chromatographie gazeuse. [Traduit par la Redaction], Introduction The effectiveness of a particular remediation technology can be evaluated by the extent of mineralization and the compositional changes that occur during the treatment. With increasing popularity of chemical [...]

Spectrum induced polarisation (SIP) is a frequency-domain method commonly used in electrical geophysical exploration. However, SIP is very sensitive to the signal-to-noise ratio of the signal, so noise reduction is very important. Independent component analysis can be used to reduce the noise of geophysical exploration data, but it cannot be used when the observed signal has only one dimension. In this paper, an empirical wavelet transform-independent component analysis method is proposed, which can be used for noise reduction in spectrum induced polarisation data. Firstly, the original measurement data are adaptively decomposed into a finite number of intrinsic modal functions by empirical wavelet transform, and then the intrinsic modal functions are selected to construct a virtual noise channel according to their correlation with the induced polarisation signal. Finally, the induced polarisation signal in the multi-dimensional mixed data is extracted by independent component analysis. Our experiment shows results show that this method can effectively remove noise signals and improve the signal-to-noise ratio of induced polarisation data. [ABSTRACT FROM AUTHOR]