Polybrominated diphenyl ethers (PBDEs) spread widely in the environment are mainly removed by photochemical and anaerobic microbial degradation. In this paper, the decomposition of 4-bromodiphenyl ether (BDE -3), the PBDEs homologues, is investigated by electron beam irradiation of its ethanol/water solution (reduction system) and acetonitrile/water solution (oxidation system). The radiolytic products were determined by GC coupled with electron capture detector, and the reaction rate constant of esol– in the reduction system was measured at 2.7×1010 L·mol–1·s–1 by pulsed radiolysis. The results show that the BDE-3 concentration affects strongly the decomposition ratio in the alkali solution, and the reduction system has a higher BDE-3 decomposition rate than the oxidation system. This indicates that the BDE-3 was reduced by effectively capturing esol– in radiolytic process.
TANG Liang XU Gang WU Wenjing SHI Wenyan LIU Ning BAI Yulei WU Minghong
A Fricke-PVA-xylenol orange (FPX) hydrogel dosimeter, in good transparency, was prepared by physical crosslinking for three-dimensional dose measurements. The process of mixing the chemical dosimeter with the PVA solution was carried out at room temperature, which reduced the influence of auto-oxidation rate. Gradation in color was obviously observed with different distance from the radiation source after 6 MeV electron beam irradiation for radiotherapy. The effects of irradiation dose and three components of the FPX gel dosimeter, i.e. ferrous ions, xylenol orange (XO) and sulphuric acid on sensitivity and stability of dose response were investigated by UV-vis spectropho-tometric measurement. The dose response of the FPX gel dosimeter was linear in the range 0~2.0 Gy. The orthogonal test was employed to find the optimal composition of the gel dosimeter with a sensitivity of about 0.095 cm-1·Gy-1. It was found that XO concentration greatly affected the sensitivity of dose response and lower concentrations of the ferrous ion and XO gave higher sensitivity within the range 0~2.0 Gy.
CAO FangqiYANG LimingCHEN JieLIN HanFAN JinchenRONG LiangLUO WenyunZHA YuanziWU Guohua
