水体系中3种常见邻苯二甲酸酯的光化学降解研究

Study on photochemical degradation of three kinds of phthalicacidesters in aqueous solution

采用固相微萃取-气相色谱-质谱联用(GC-MS)技术,研究了不同介质、光源、起始浓度、H2O2浓度等对3种常见邻苯二甲酸酯(PAEs)光化学降解过程的影响,并对邻苯二甲酸二(2-乙基己基)酯(DEHP)光降解的中间产物进行了检测,提出了可能发生的降解路径.结果表明:在不同介质中,邻苯二甲酸二甲酯(DMP)和邻苯二甲酸二乙酯(DEP)在Millipore-Q水中降解速度最快,而DEHP在天然海水中降解速度最快;3种PAEs在紫外灯照射下比模拟日光下降解速度快;相同紫外光照条件下,不同初始浓度的DMP、DEP和DEHP在研究浓度范围内(0.5~10μg·L-1)的光降解率随着浓度的增加呈现减小趋势;此外,体系中H2O2的存在会明显加快PAEs的降解速率;通过GC-MS分析,检测出了DEHP在UV/H2O2条件下降解产生的中间产物,并且发现DEHP是从侧链开始降解的.

The photodegradation processes of three kinds of common phthalate esters（ PAEs） under different media,light source,initial concentration and concentration of H2O2 were studied by solid phase microextraction-gas chromatography-mass spectrometry（ GC-MS）. The photodegradation intermediates of di-（ 2-ethylhexyl） phthalate（ DEHP） were detected and the possible degradation pathways were proposed. The results showed that the photoreaction rates of dimethyl phthalate（ DMP） and diethyl phthalate（ DEP） were the highest in Millipore-Q water,whereas that of DEHP was the highest in natural seawater. The photodegradation rates of three kinds of PAEs under UV irradiation were much faster than those under simulated sunlight.Exposed to the same UV lamp,the photodegradation rates of DMP,DEP and DEHP decreased along with the increase of initial concentrations（ 0.5 - 10μg·L-1）. In addition,H2O2 could significantly accelerate the degradation rates of PAEs. Based on GC-MS analysis,the intermediate products of DEHP degradation in the UV/H2O2 system were detected. We could infer that the degradation occurred on the side chains of DEHP.