Abstract
Polychlorinated biphenyls (PCBs) are a class of synthetic organic chemicals consisting of from one to ten chlorine atoms bonded totwo phenyl rings that create up 209 possible variations referred to as congeners. PCBs were commercially produced world-wide on a large scale between the 1930s and 1980sthat had been used widely in variety of commercial equipment like transformers, capacitors and other electrical equipment because of their useful quality as being a fire retardant. But due to their persistence and ubiquitous distribution in the environment, PCBs were banned from the U.S in the 1970s and internationally through the Stockholm Convention on Persistent Organic Pollutants. Although banned by law and punished heavily, large numbers of PCB-contaminated transformers are still in service. Thus, there remains a huge reservoir of PCBs with the potential to serve as sources of contamination to the environment. In this study, using EN 12766 test method: “Petroleum products and used oils-Determination of PCBs and related products”, PCBs were analyzed in the random samples collected from different regions of Turkey. The samples also used for screening for the presence of total halogens and chlorine. Test results of the study showed that PCBs were present in certain transformers but concentrations in the most of samples did not exceed the limit value of 50 ppm.However, there was a significant relationship between the PCB concentrationsand the halogens.Finally, the contaminated transformer oils were evaluated according to Regulation on Control ofWaste Oils.
Highlights
Introduction chlorinated biphenyl is shownFigure 1.POLYCHLORINATED biphenyls (PCBs) have been recognized as an environmental pollutant in 1966 when they were catalogued as hazardous waste [1]
Test results of the study showed that Polychlorinated biphenyls (PCBs) were present in certain transformers but concentrations in the most of samples did not exceed the limit value of 50 ppm.there was a significant relationship between the PCB concentrationsand the halogens.the contaminated transformer oils were evaluated according to Regulation on Control ofWaste Oils
PCB (CAS number 1336-36-3), C12H10nCln, are manmade organic aromatic hydrocarbons that have 1 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings each containing six carbon atoms [2]
Summary
Introduction chlorinated biphenyl is shownFigure 1.POLYCHLORINATED biphenyls (PCBs) have been recognized as an environmental pollutant in 1966 when they were catalogued as hazardous waste [1]. PCB (CAS number 1336-36-3), C12H10nCln, are manmade organic aromatic hydrocarbons that have 1 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings each containing six carbon atoms [2]. The variable molecular composition of PCB allows different structural configurations due to possibility of different arrangements of chlorine atoms on the benzene rings of the PCB molecule. 209 different congeners (isomers), depending upon the number and positions of the chlorine atoms, are possible comprising the entire set of homologues and isomers, but only about 130 of these are likely to occur in commercial products [3]. All congeners of PCBs are lipophilic but different congeners sometimes act differently from one another and water solubility decreases as the degree of chlorination increases [4]
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