An Approach to Reuse of PCB-Contaminated Transformer Oil Using Gamma Radiolysis

Abstract

The radiolytic decompositions of low-concentration polychlorinated biphenyls (PCB) and 1,2,4trichlorobenzene (TCBz) in a transformer oil have been studied using a 60 Co gamma ray irradiation facility. Significant decompositions of PCB and TCBz were observed in the oil at tens of kGy absorbed dose without any additive. We derived the required dose for KC500 decomposition in transformer oil using a power function, which indicates that oil with lower PCB concentration needs less dose to treat PCB wastes. We also observed that the gamma radiolyses of PCB and TCBz did not affect each other; the decompositions of PCB and TCBz proceed independently. Both PCB concentration analysis and total chlorine mass concentration analysis indicated that most dechlorinated chlorine atoms react to generate other chlorine compounds in the oil. We found that the gamma radiolysis without additional compounds in the oil can be a useful way of reusing PCB-contaminated transformer oil.

A Comparative Study of the Radiolysis of Used Transformer Oil and Oil Containing 1, 2, 4-Trichlorbenzene Under the Influence Of Gamma-Radiation

“…Under normal conditions, transformer oil can dissolve a fairly large amount of air (10% of the oil volume). The oxygen content in air dissolved in transformer oil is 30.2% [5,7].…”

“…The high radiation resistance of 1, 2, 3, 4tetrachlorbenzene was observed in [4], where it was irradiated in insulating oil at 114 kGy adsorbed dose. The γ-radiolysis of TCB in transformer oil was provided in [5] at 0,9 kGy/h dose rate and range of dose 13…108 kGy. It was shown that the main products of γ radiolysis of 1, 2, 4-trioclorbenzene in transformer oil are 1, 3-dichlorbenzene, 1, 4-dichlorbenzene and monochlorbenzene.…”

“…Decomposition degree of TCB (200 mg/kg) is 65% at 108 kGy. Dose constant is equal to 8.5•10 -3 kGy -1 [5].…”

Radiolytic degradation of 1,2,4-trichlorobenzene (TCB) in some organic solvents by gamma rays: The kinetic properties of complete dechlorination of TCB and its pathway

“…In the published patent No: CN1277755C in China, HCB utilization and technical scheme have been shown. Some scientific studies have been conducted on the degradation of CBs through γ-irradiation [ 20 , 21 , 22 , 23 ]. In the study of [ 23 ] TCB has been irradiated in the transformer oil without any additive and >99 % conversion of TCB has been achieved.…”