基于水合电子的新型亚硫酸盐/UV体系对多溴联苯醚的还原降解及脱溴机理

Polybrominated diphenyl ethers (PBDEs) are typical persistent organic pollutants (POPs), and their debromination is a feasible and affordable remediation and detoxification method. However, it is still a challenge that the current heterogeneous remediation technologies like zerovalent metals and photocatalysis are restricted by the requirements of certain solvents and relatively low efficiency of debromination due to the heterogeneous reactions. The project proposes a hydrated electron-based homogeneous sulfite/UV system and is aimed to provide an efficient alternative to reductive debromination of PBDEs. With decabromodiphenyl ether (BDE-209) selected as the target compound, the research is intended to (i) study the degradation kinetics and debromination efficiency of BDE-209, (ii) elucidate the degradation pathways and debromination mechanisms of BDE-209 by quantitatively determining the formation and transformation of main reactive species, by investigating the effects of bromine substitution position and substitution degree on the debromination kinetics of PBDEs, and by exploring the formation of the intermediate products, (iii) clarify the roles of water parameters and operation conditions, (iv) and set up degradation and debromination modeling of BDE-209 in the system, which is subsequently validated and optimized in the realistic water matrix. The study will provide a feasible and promising approach to the efficient debromination of PBDEs.

多溴联苯醚（PBDEs）是一类高稳定持久性有机污染物，脱溴是其降解脱毒的可行途径之一。目前常用的零价铁、光催化等异相脱溴技术因受限于界面吸附与界面反应等过程,对溶剂环境要求较高，脱溴效率偏低。本项目拟以十溴联苯醚(BDE-209)为目标物，提出基于水合电子的亚硫酸盐/UV均相还原体系用于PBDEs的还原脱溴。研究体系中BDE-209的降解动力学及脱溴效率；从水合电子的生成与转化规律、溴取代位置和取代程度对PBDEs脱溴动力学的影响以及降解产物的生成等角度，阐明由水合电子引发的BDE-209降解路径与脱溴机理；解析水质参数及体系条件对其降解与脱溴效能的影响；建立BDE-209降解及脱溴的数学模型，并针对水质本底验证模型和优化参数，为发展高效的PBDEs均相脱溴技术提供理论依据及技术参考。

以多溴联苯醚（PBDEs）为代表的持久性有机污染物对生态环境及公共安全造成了越来越大的风险。为了解决目前绝大多数技术对PBDEs降解及脱溴效率偏低的问题，本项目利用水合电子（eaq-）极强的还原活性，提出并发展了新型的亚硫酸盐/紫外高级还原体系。以一氯乙酸为模型化合物，利用动力学分析的方法，研究了典型影响因素（亚硫酸盐浓度、pH、温度、紫外光强度、天然有机物、碱度、亚铁离子、实际水质本底等）对该体系还原效能的影响；通过对体系中活性物种的定型鉴定与定量分析，揭示了该体系中主要活性物种是eaq-，探讨了由eaq-引发的还原脱卤机理；在此基础上，从体系中活性物种生成与相互转化动力学的角度，建立了该体系中还原脱卤的稳态模型及具有更强适应性的复合模型，优化了体系参数，从而构建了亚硫酸盐/紫外高级还原体系。以BDE-3、BDE-209以及典型溴代芳香和链式有机化合物为目标物，解析了典型影响因素（亚硫酸盐浓度、pH、温度、溶解氧、有机溶剂等）对该体系降解与脱溴效能的影响规律；鉴定分析了该体系中实现还原脱溴的主要活性物种，并证实了eaq-的主要脱溴作用；从体系中活性物种生成与转化规律、溴取代位置和溴代程度对脱溴效能影响规律以及降解产物生成等角度，探讨了在该体系中PBDEs可能的降解路径与脱溴机理。本项目所建立与发展的亚硫酸盐/紫外高级还原体系将为高稳定毒性卤代有机污染物的高效降解与有效脱毒提供理论依据与技术参考。