Improving transformer oil decontamination: A synergistic approach integrating adsorption and radiative treatment for polychlorinated biphenyls

Addressing the challenge of removing polychlorinated biphenyls (PCBs) from transformer fluids is crucial for environmental protection in the energy sector due to the widespread use of transformers in various industries. However, current methods lack efficiency in enabling fluid reuse, creating a significant research gap. In this study, we focus on the recycling of oils from power transformers contaminated with polychlorinated biphenyls while preserving the chemical and physical attributes of the original transformer oil. To this end, we employ a combination of UV-visible radiation exposure and an adsorption treatment using activated bauxite Fuller's earth (BFE) (containing 92% Al2O3). The effects on fluid remediation are systematically assessed using various analytical methods, including nuclear magnetic resonance spectroscopy (NMR), breakdown voltage testing, acidity titration, and gas chromatography coupled with mass spectroscopy (GC/MS). The experiments in static mode showed that the concentration of PCBs was reduced to a value lower than 50 ppm after 8 h of irradiation while the formed chlorinated acid compounds can be removed using BFE sorbent. The results of our treatment demonstrated the performance of the combination of UV-visible radiation and the adsorptive treatment of transformer oils while improving their physicochemical characteristics.