Detection And Direct Photolysis Of Endocrine Disrupting Chemicals In Water

Environmental endocrine disrupting chemicals (EDCs), or named as environmental hormones, are defined as exogenous substances that interfere with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body that are responsible for the maintenance of homeostasis, reproduction, development, and/or behavior. Under some circumstances, they may induce hypertrophy and tumor of tissues and/or organs.Environmental EDCs is a pop research topic of environmental chemistry. Environmental chemistry will play extremely essential role in the screen, identification, monitoring, environmental behavior (including transport, transform and fate) and ecological effects researches and pollution control of EDCs.Now, GC and GC/MS exert important action in detect of environmental endocrine disrupting chemicals, which already are one of the most effective means in detect of environmental endocrine disrupting chemicals, this thesis detect the content of EDCs in habitation water by GC/MS in Luojiashan of Wuhan; This thesis is focused on the photolysis of diethylstilbestrol (DES) and bisphenol-A (BPA) in water induced by UV-light. The many factors, such as pH value, light source and the initial concentration affected on the degradation were evaluated. Furthermore, the intermediate products of DES and BPA during the UV-light process have been identified by gas chromatography-mass spectrometry (GC/MS), the degradation pathway was proposed on the base of the evidence of the intermediate formation. This study will to find out direct photo degradation feasibility of DES and BPA in UV. The main results and conclusion are presented as below.1. We detect the content of some EDCs in residential sewage of Guangba road, Luojiashan of Wuhan, tap water and bottled water in campus of Wuhan University. Eight EDCs have been detected in residential sewage, its concentration ranges are ng/L level, however, the content of NP and DBP are up to μg/L level. Estriol was also detected in residential sewage. DBP, DEHP and alkylphenol were detected in tap water and bottled water. E1 was detected in tap water which concentration was 7.38ng/L; BPA was detectedin bottled water that the concentration was 32.85ng/L; this is higher than in tap water, the reason is maybe that BPA dissolves to water from plastic easily.2. DES and BPA have the similar photolysis act during the UV-light irradiation. At pH, values over the range of 3.0-10.0, the degradation rate of DES and BPA was continuously increasing with the increase of pH value. The degradation was fastest at pH 10.0; The irradiation of high-pressure mercury lamp was almost no action in the degradation of DES and BPA; The degradation of DES and BPA follow a pseudo first-order kinetic law at the range of 5.0-50.0 ng/L of the initial concentration; the first-order rate constant of DES and BPA equal to 0.1255mm~-1 and 0.01985 min~-1, respectively.3. The degradation mechanism of DES induced by UV-light has three pathways: 1) DES generates polymerization and produces dimeric DEC by dehydrogenation. 2) Under UV irradiation, DES produces DES-o-catechol, and then DES-o-catechol is changed into 4, 4'-hydroxyl-DES-3-semiquinone. 3) DES is oxidized to 2,2-dienestrol by dehydrogenation, and then the chain cleavage to produce l-(4-hydroxyphenyl)-propan-l-one.4. The degradation mechanism of BPA induced by UV-light is: 1) the hydroxyl radicals attack the BPA molecule in the 3-position, which makes BPA molecule cleavage to produce phenol and 4-isopropyl-phenol. Phenol is changed into 2-methyl-2, 3-dihydro-benzofuran; 4-isopropyl-phenol is further oxidized to form 4-vinyl-phenol under the action of hydroxyl radicals. 2) Under the action of hydroxyl radicals, BPA is oxidized to 3-(4-hydroxyphenyl)-3-methyl-2-oxobutanoic acid.