The Degradation Of Tetrabromobisphenol-A In Soil Under Sludge-lysate And CaO₂ Nanoparticles System

Now TBBPA is most widely used brominated flame retardants. But the study showed that it was toxic. If it was not treated by appropriate methods, it would be harmful to our health and the environment. TBBPA was slightly soluble in water. So it was very easy to gather in the soil and pollute it. The reports about the degradation of TBBPA in soil are less. The major methods of the degradation of TBBPA included chemical degradation, photochemical degradation and biological degradation. This paper first applied the CaO2 nanoparticles and sludge-lysate to degrade the TBBPA in soil and had made some progress.First, CaO2 nanoparticles were prepared by the calcium chloride anhydrous, hydrogen peroxide and different dispersants. The dispersants were the normal polyethylene glycol 1000 and the sludge-lysate which was prepared by the residual sludge broken by the sodium hydroxide. It showed that when the polyethylene glycol 1000 was added into the preparation. The yield and purity of CaO2 nanoparticles reached to 68.46% and 65.55%, respectively. The size of the CaO2 nanoparticles was between 100 and 250 nm. When the sludge-lysate was applied for the preparation, the yield and purity of CaO2 nanoparticles reached to 66.91% and 65.51%, respectively. The size of the CaO2 nanoparticles was between 100 and 200 nm. It was seen that the sludge-lysate could be used as the dispersant and had good dispersion effect. It was a new way for the disposal of residual sludge.Besides, this study explored the detection of TBBPA in the soil under different systems. First,50? was determined as the drying temperature. When the TBBPA in the contaminated soil, contaminated soil with water or contaminated soil with the water and CaO2 nanoparticles was extracted by the sodium hydroxide, the absolute error of them was 2.38%,2.08% and 17.36%, respectively. And the appropriate pH of the test soil of them was 9.0. And the method of ethyl acetate to extract TBBPA from the contaminated soil with sludge-lysate's system was more accurate than the sodium hydroxide. The absolute error of later was 30.94%. But the absolute error of former was only 6.02%.The degradation of TBBPA in soil was studied under different systems on the basis of the explicit test method and condition. Sludge-lysate, CaO2 nanoparticles and water were added into the contamintaed soil at the same time or separately to establish different systems. Results showed that the optimized system to degrade the TBBPA in the soil was sludge-lysate with the addition of CaO2 nanoparticles. The degradation of TBBPA (50 mg/kg) reached to 71.85% under the following optimum conditions:the amount of CaO2 nanoparticles 0.2 g, the degradation time 20 days.Based on the above studies, the degradation mechanism of TBBPA in soil was explored in the paper. The effect of the dehydrogenase activity and microorganism in the soil on the degradation of TBBPA was studied It was supposed that TBBPA was degraded by the biological and chemical processes. According to the identified intermediates by the LC-MS, the possible pathway for the degradation of TBBPA in the contaminated soil under the sludge-lysate with CaO2 nanoparticles might include three ways:debromination, beta scission and methylation.