Study On Degradation Of DCP And BDE-209 By UV Assisted Chemical Method

Halogenated organics has chemical stability and are easy to accumulate in the living body. They also have strong toxicity and higher three?carcinogenic, mutagenic and mutagenic?, which has a large part of the environmental priority control pollutants.In the paper, we choose dichlorophenol and decabromodiphenyl as examples of halogenated organics. Dichlorophenol is one of the main pollutants in natural water and drinking water in China. While decabromodiphenyl can be released into the environment in the process of using, they both can cause pollution to water, atmosphere, soil and biosphere. UV assisted chemical method is consist of UV catalytic wet oxidation process and UV advanced reduction process.We tried to choose the optimal conditions for degradation. Then, the detection of the halogen ions and the intermediate products were carried out.We used UV catalytic wet oxidation process to degradate DCP. And found the degradation effect of DCP was remarkable. When the concentration of DCP solution was 50 mg/L, the best conditions were:p H was 3, H₂O₂ concentration was 50 ?mol/L, Cu SO₄ concentration was 1 g/L, UV intensity was 3.5 W/m2. After 40 min reaction, the removal rate of DCP was 88.74%. Then the chloride ions and TOC were analyzed, it was found that the removal effect were both obvious. So this method not only has the function of removing chlorine, but also can turn DCP into CO2 and water.We used UV advanced reduction process to degradate DCP. We chose Na₂SO₃ and Na BH₄ as the reductant, and found out the effect of Na BH₄ was slightly stronger than that of Na₂SO₃. When the concentration of DCP solution was 50 mg/L, the best conditions were:p H was 12, concentration of Na BH₄ was 2 mmol/L, UV intensity was 3.5 W/m2. After 60 min reaction, the removal rate of DCP was 83.79%. Then chloride ions and TOC were determined, it was found that the degradation of the dichlorophenol was only dechloridation.After a significant effect of the UV advanced reduction method, we chose BDE-209 as the target, which is more difficult to degrade. We also selected Na₂SO₃ and Na BH₄ as the reductant, and found out the effect of Na BH₄ was slightly stronger than that of Na₂SO₃. When the concentration of BDE-209 solution was 40 mg/L, the best conditions were:p H was 12, concentration of Na BH₄ was 2 mmol/L, UV intensity was 3.5 W/m2. After 60 min reaction, the removal rate of BDE-209 was 89.25%. Then we used GC-MS to text intermediate product, and found debromination is the mean process. The nine and eight brominated diphenyl ether are the main intermediate products. The degradation of BDE-209 was mainly debromination and will take off bromine atoms one by one.