卤代芳烃在环境友好高级氧化过程中产生内源性化学发光的分子机制及应用研究

Intrinsic Chemiluminescence Production during Environmentally-friendly Advanced Oxidation of Halogenated Aromatics and Its Applications

卤代芳烃类有机物是一类在环境中分布极其广泛,且对生物体具有强致癌性的一类物质.近年来,这类物质因其可能导致对人体健康以及生态系统的潜在环境风险而被公众日益关注.高级氧化过程(AOPs)作为一种"环境友好"的技术被越来越多地用于对这类高毒性且难降解有机物污染的土壤或水体进行修复.在最近的研究中,我们发现由高级氧化介导的持久性有机污染物如五氯酚以及其它卤代芳烃的降解过程中会产生内源性的化学发光,并且这种内源性的化学发光直接依赖于该过程中产生的极具活性的羟基自由基(·OH).我们认为该反应过程中生成了某种依赖于·OH形成的醌中间体以及激发态多羰基产物,正是它们导致了这种不同寻常的化学发光.在上述研究基础上,进一步开发出一种快速灵敏且简单有效的化学发光分析手段用于定量检测痕量的卤代芳烃,并将其成功应用于这些持久性有机污染物降解动力学的实时监测.

Haloaromatics （XAr） have been widely used as pesticides, personal care agents, pharmaceuticals and flame retardants, which are now ubiquitously present in our environment. The carcinogenicity coupled with their ubiquitous occurrence have raised public concerns on the potential risks to both human health and the ecosystem posed by XAr. Advanced oxidation processes （AOPs） have been increasingly employed as an ＂environmentally-friendly＂ technology for remediating such highly toxic and recalcitrant XAr. During these AOPs systems, the most reactive radical intermediate formed at near-ambient temperature and pressure is the hydroxyl radical （·OH）. Recently, we found that an intrinsic chemiluminescence can be generated during the advanced oxidation of the priority pollutant pentachlorophenol and all other XAr. Furtherly, by the complementary application of electron spin resonance （ESR） with 5,5-dimethyl-l-pyrroline-N-oxide （DMPO） as the spin-trapping agent, fluorescence method with terephthalic acid （TPA） as the ·OH probe, chemiluminescence analysis in the presence of classic ·OH scavengers and several typical ·OH-generating systems, the chemiluminescence was confm-ned to be directly dependent on the production of the extremely reactive ·OH. Further studies showed that halogenated quinoid intermediates were produced during the degradation of XAr by ·OH-generating system, which could produce weak chemiluminescence that was greatly enhanced by addition of extra ·OH. We proposed that this unusual chemiluminescence generation was due to hydroxyl radical-dependent production of halogenated quinoid intermediates and electronically excited carbonyl species. In addition, the time course of chemiluminescence emission correlated well with the degradation of XAr： when the degradation level of XAr reached the maximum, no further chemiluminescence emission could be observed. Based on these findings, we developed a rapid, sensitive, simple, and effective chemiluminescence method to not only measure trace amount of XAr, but also monitor their real-time degradation kinetics. These new findings may have broad chemical, pharmaceutical, toxicological and environmental implications for future studies on remediation of these halogenated persistent organic pollutants by AOPs.