摘要
Deca-BDEs(十溴联苯醚)可在光照、微生物作用、高温下通过降解脱溴转变为毒性更强的低溴系联苯醚.BDE209是DecaBDEs的主要成分,研究BDE209的环境降解行为对确定环境中低溴系联苯醚的来源进而消除其对环境的污染具有重要意义.已有研究从BDE209降解机理向分析不同光源、不同降解阶段的降解产物推进,并以探求快速、有效的处置技术为出发点,对影响BDE209降解行为的辐照光强、有机溶剂的种类、固相介质等相关因素进行实验室模拟和对比分析,研究结果表明,太阳光照下BDE209的降解速率小于紫外光源,降解程度也低于紫外光源,二者的降解产物也有所不同.光降解是Deca-BDEs在环境中转化的最主要途径,现有研究揭示了BDE209的光降解反应遵循准一级反应,表明其主要是一个逐级脱溴的过程,最终降解产物中含有大量的低溴系同系物,但鲜见对光解反应过程中潜在的一系列降解步骤及全面的光降解机理的研究,未来对相关机理、影响因素及降解途径的阐述仍需完善.对微生物降解的研究主要集中在细菌、淀粉酶等特定微生物种类的降解特性(包括降解速率、降解效果)方面,对Deca-BDEs降解途径、转化及降解产物的鉴定尚不完全清楚.此外,对高温下Deca-BDEs转化为溴代二英的机理研究比较缺乏.由于BDE209具有极高的疏水性,并且其在大气中主要以固相形式存在于颗粒物中,因此今后的研究应更注重BDE209的气相和固相的光降解行为,注重微生物降解法在Deca-BDEs污染土壤修复技术的应用以及电子废物拆解过程中Deca-BDEs的降解途径和影响因素等方面.
At high temperatures or under sunlight, Deea-BDEs can be transformed and depredatcd by microbial action into low brominated diphenyl ethers, which are more toxic. Since BDE209 is the main component of Deca-BDEs, it is very important to study the environmental degradation behaviors of BDE209 to determine the source of lower brominated diphenyl ethers and thus eliminate the environmental pollution. This study moves forward from the degradation mechanism to analyzing the degradation products in different lights and at different degradation stages. Moreover, in order to explore faster and more effective disposal technology, the present study carried out laboratory simulation tests and comparative analysis tests for related factors such as irradiation intensity, different organic solvents and solid medias that influence the degradation behaviors of BDE209. The results showed that, the degradation rate as well as the degradation degree of solar are slower than that of UV light; the degradation products are also different for the solar and UV lights. In the environment, photodegradation, among the aforementioned mechanisms, is the primary pathway for Deca-BDEs to be degraded. This study revealed that the photodegradation reaction is a first order reaction, and debromination occures step-by-step with the final degradation productions containing much low bromine generation homologue. However, a series of potential degradation steps during the photolysis reaction and whole photodegradation mechanism remain to be investigated. Meanwhile, the study of Deca-BDEs calls for a clear description of photodegradation mechanisms, the influencing factors, and the degradation pathway. The studies on microbial degradation mainly focus on the degradation characteristics of specific microorganism categories such as bacteria and amylase (including degradation rate and degradation effect), but the degradation pathway and transformation of Deca-BDEs as well as the degradation product identification are not entirely clear. In addition, the mechanism of Deca-BDEs transformation into brominated dioxins (PBDD/Fs) at high temperature is not thoroughly analyzed. Due to the high hydrophobicity of BDE209, it mainly exists in the solid particles in the atmosphere. Therefore, future research should focus more on the photodegradation behavior of BDE209 in gas eous and solid phases. More attention should also be paid to microdegradation as the remediation technology for sites contaminated with Deca-BDEs, as well as the degradation path and influencing factors of Deca-BDEs during the process of dismantling electronic waste.
出处
《环境科学研究》
EI
CAS
CSSCI
CSCD
北大核心
2014年第5期554-559,共6页
Research of Environmental Sciences
基金
国家环境保护公益性行业科研专项项目(201009026)
关键词
十溴联苯醚
光降解
微生物降解
高温分解
Deca-BDEs
photodegradation
microbial degradation
thermal decomposition