【作者】 刘慧；

【导师】 全燮；

【作者基本信息】 大连理工大学 ， 环境工程， 2011， 博士

【摘要】 卤代有机物对人体健康和生态环境安全构成严重威胁,日益受到人们重视。随着工业文明的发展,人为生产排放的卤代有机物逐渐增加,但这并不是环境中卤代有机物的唯一来源,许多天然过程也能产生卤代有机物。在自然水体中,光化学过程是有机物转化的重要过程之一,而水体中的多种成分将导致有机物经历不同的光转化途径。本论文研究了酚类物质在含盐水体中光化学转化形成卤代酚类物质以及卤代酚类物质光转化形成毒性更大的持久性有机卤代物的过程,取得了以下结果：(1)双酚A(BPA)在氯离子溶液中能发生光致氯代反应。汞灯照射下(λ>290nm),在含0.66 mM Fe(Ⅲ)的氯离子溶液中(pH=3.0),检测到BPA (C0,BPA=87.7μM)光反应过程产生的2-(3-氯-4-羟基苯基)-2-(4-羟基苯基)丙烷(3-ClBPA) (328 nM)和2,2-二(3-氯-4-羟基苯基)丙烷(3,3-diClBPA) (1.1nM)两种氯代衍生物。3-ClBPA和3,3’-diClBPA的形成量随着Fe(Ⅲ)浓度增加而增加,随着pH升高而减少。激光闪光光解(LFP)和电子顺磁共振(EPR)表明Cl2·-是主要的活性氯物种,Fe(Ⅲ)光照产生的·OH是形成Cl2·-的重要因素；随着pH升高Cl2·-和·OH的数量均减少,氯代反应减弱。(2)地表水中的富里酸(FA)显著影响BPA的光致氯代反应。FA和Fe(Ⅲ)通过形成Fe(Ⅲ)-FA络合物而增加Cl2·-的形成量,进而增强BPA的氯代反应。氙灯照射下(λ>290nm),87.7μM BPA在0.13mMFe(Ⅲ)和3.2mg/L FA共存的盐溶液中(pH=6.3)光反应形成16.7nM 3-ClBPA。FA对BPA的光致氯代反应表现出双重作用,当[FA]<3.2mg/L,随着[FA]增大,3-ClBPA的形成量增加；当[FA]增大至10 mg/L,3-ClBPA的形成量降低至5 nM。天然海水中的实验表明,87.7μM BPA在海水中发生光致氯代反应形成～2nM 3-ClBPA。(3)酚类化合物在Fe(Ⅲ)和Cl-共存的酸性溶液中发生了显著的光聚合反应。汞灯照射下(λ>290nm), BPA在Fe(Ⅲ)和Cl-共存的酸性溶液中(pH=2.5～3.5)形成了大量的二聚体和三聚体;苯酚,2-氯酚,2,4-二氯酚在Fe(Ⅲ)和Cl-共存的溶液中(pH=3.0)均发生聚合反应形成(氯代)羟基联苯醚和(氯代)羟基联苯结构；在含Fe(Ⅲ)的溶液中(pH=3.0),五氯酚在光照条件下形成八氯代二苯并二噁英(OCDD)的量随着Cl-浓度增加而显著增加。(4)苯酚在溴离子溶液中发生光致溴代反应形成溴代苯酚,而溴代苯酚进一步光聚合形成羟基多溴联苯醚(OH-PBDE).氙灯照射下(λ>290nm),苯酚在含有溴离子的水溶液中形成了2-溴苯酚和4-溴苯酚,而共存的氯离子可以提高溴代苯酚的形成量。2,4-二溴苯酚(2,4-diBP)在水溶液中通过光反应形成了2’-OH-BDE68,而且随着光强和2,4-diBP初始浓度增加,2’-OH-BDE68的形成量逐渐增大；而pH升高,2’-OH-BDE68的形成量降低。分别检测了模拟海水和天然海水中由2,4-diBP光反应形成2’-OH-BDE68的量。结果表明在λ>370nm的光照射下,在pH=8.0的模拟海水中,Fe(Ⅲ)浓度的增加显著提高了2’-OH-BDE68的形成量；天然海水中,2,4-diBP(C0,diBP=10～100μg/L)的光转化反应形成了1.38～28.6 ng/L 2’-OH-BDE68,而2,4-diBP(C0,diBP=100μg/L)和苯酚(C0,P=37.5,124μg/L)的光转化反应形成了0.16～0.88 ng/L 2’-OH-BDE7。以上结果表明,在含有卤素离子的水溶液中,非卤代酚能发生光致卤代反应形成卤代酚,而卤代酚能通过进一步光化学转化过程形成OH-PBDE和二噁英等毒性和生态风险性更大的卤代有机物,这说明在自然环境中,尤其是海洋环境,有机物能通过光转化反应形成毒性更大的卤代有机污染物,这对人们认识和了解部分有机卤代物的天然来源和归宿具有重要的价值。更多还原

【Abstract】 Halogenated organic pollutants have received extensive attention due to their complex damage effects on the human health and the ecological environment. Their sources were once considered to be predominantly anthropogenic due to their large scale production, widespread use and improper handling. However, many uncertainties exist regarding the origination of halogenated organic pollutants in environment. Photochemical process is one of the most important transformation pathways for organic compounds in natural environment, and many components of natural water could impact the phototransformation pathway of the organic pollutants. Investigation of the photochemical formation of the halogenated organic compounds from the non-halogenated compounds in saline water, and the subsequent formation of the more toxic and persistent pollutants will be more helpful for better understanding the natural sources of halogenated organic compounds in environment. In this dissertation, the following works have been done:(1) The photochemical formation of chlorinated organic compounds was investigated in saline water, using bisphenol A (BPA) (C0, BPA=87.7μM) as a model molecule. The chlorinated derivatives 2-(3-chloro-4-hydroxyphenyl)-2-(4-hydroxyphenyl) propane (3-ClBPA) (328 nM) and 2,2-bis(3-chloro-4- hydroxyphenyl) propane (3,3’-diClBPA) (1.1 nM) were determined during the phototransformation of BPA in saline solution with Fe(III) at pH3.0 under Hg lamp irradiation (λ>290 nm). The amounts of 3-ClBPA and 3,3’-diClBPA increased with the increase of Fe(Ⅲ) concentration, but decreased with the increase of pH. Laser flash photolysis (LFP) and electron paramagnetic resonance (EPR) results indicated that the chlorination of BPA was most likely due to the formation of Cl2·- radical as a consequence of Fe(Ⅲ) irradiation, yielding Cl·and·OH radical species and finally forming Cl2·- radical upon further reaction with chloride. Moreover, the amount of Cl2·- and·OH decreased with the increase of pH, thereby weakened the photochlorination reaction.(2) The effects of Fe(Ⅲ) and fulvic acid (FA) on the photochlorination of BPA were investigated under Xe lamp irradiation(λ>290 nm). Formation of Fe(Ⅲ)-FA complex promoted the BPA chlorination through producing more Cl2·- radical. FA presented two opposite effects:BPA chlorination was enhanced with the increase of FA concentration ([FA]) when [FA]<3.2mg/L; the amount of 3-ClBPA was as high as 16.7 nM when [FA]=3.2 mg/L; however, it reduced to 5 nM when [FA]=10 mg/L. Phototransformation of 87.7μM BPA in the natural seawater resulted in～2 nM 3-ClBPA.(3) Phototransformation of BPA in saline solution with Fe(Ⅲ) under acidic conditions (pH=2.5～3.5) resulted in the formation of BPA dimers and trimers. Photopolymerization of phenol,2-chlorophenol and 2,4-dichlorophenol resulted the structures of (chlorinated) hydroxydiphenyl ether and (chlorinated) hydroxydiphenyl in the coexistence of Fe(Ⅲ) and chloride at pH3.0. Phototransformation of pentachlorophenol resulted in larger amount of octachloro-dibenzodioxin (OCDD) in acidic saline solution (pH=3.0) than in fresh water.(4) Phototransformation of phenol in water containing bromide resulted in bromophenols, and the photopolymerization of bromophenols led to the production of hydroxylated polybrominated diphenyl ethers (OH-PBDEs). Phototranformation of phenol in the bromide solution resulted in 2-bromophenol and 4-bromophenol, and chloride promoted the bomination reaction. When 2,4-dibromophenol was irradiated in aquatic solutions under Xe lamp irradiation (λ>290 nm), significant amounts of 2’-hydroxy-2,3’,4,5’-tetrabromodipheyl ether (2’-OH-BDE68) were rapidly formed as the dimeric product of 2,4-diBP. The formation of 2’-OH-BDE68 intensified with the increase of light intensity and with the initial concentration increase of 2,4-diBP, whereas it weakened with an increase in pH. Moreover, Fe(Ⅲ) and fulvic acid played important roles in the formation of 2’-OH-BDE68. The amount of 2’-OH-BDE68 from the phototransformation of 2,4-diBP was determined in the simulated seawater and natural seawater, respectively. Fe(Ⅲ) significantly promoted the formation of 2’-OH-BDE68 in the simulated seawater at pH=8.0 under light ofλ>370 nm. Phototransformation of 2,4-diBP (C0, diBP=10～100μg/L) in natural seawater resulted in 1.38～28.6 ng/L 2’-OH-BDE68, and phototransformation of 2,4-diBP (C0,diBP=100μg/L) and phenol (C0,P=37.5,124μg/L) in natural seawater resulted in 0.16-0.88 ng/L 2’-OH-BDE7.The results of the experiments in this dissertation demonstrated that phototransformation of phenolic compounds in the saline water could result in halogenated phenols. Moreover, phototransformation of these halogenated phenols could lead to some more toxic pollutants, such as, OH-PBDEs and dioxins. These findings provide an important insight into the possible source of halogenated organic pollutants in natural aquatic systems through photochemical approaches, and are significant for better understanding the natural sources of halogenated compounds in the environment.更多还原