Mechanism Research And Removal Of17β-Estradiol In Aqueous Solution By Dielectric Barrier Discharge Over Water Process (DBD_OW)

The safety of drinking water is vital for the survival of mankind. Environmental estrogens are kinds of chemicals which can disrupt the balance of normal endocrine system, such as reproduction, growth and behavior. Seriously, they have been threaten to the safety of drinking water. Steroid estrogens are kinds of natural estrogens which can not only cause the diseases (carcinogenic, teratogenic and mutagenic), but also interfere with the reproductive genetic function of human and animals.17β-estradiol (E2) is one of the strongest with estrogenic activity steroid estrogens. For its stable chemical structure, it has low degradation rate with biological means. Dielectric Barrier Discharge over water process (DBDOW) is one of new advanced oxidation water treatment technologies. It has some advantages such as high removal efficiency and no secondary pollution. This paper studied the removal of E2by plasma induced from DBDOW reactor.The treatment objects of this experiment were simulation liquor of estrogens which were diluted by pure water. Solid phase extraction enrichment (SPE) and high performance liquid chromatographic(HPLC) were used as the analytical methods of estrogens in water.In order to investigate the removal of typical estrogens by conventional treatment process in Nanning water plant, E1, E2and E3were selected as the target compounds. The concentration of three estrogens in Nanning conventional water treatment plant was analyzed by SPE-HPLC. The concentration of E1, E2and E3in influent was9.46,19.20and21.78ng/L, respectively. After treatment, the content of E1, E2and E3were2.74,10.48and7.04ng/L in effluent. The removal rates were71.0,45.4and67.7%. And the content of this three typical environmental estrogens in water are still high.In addition, the degradation of E2using DBDOW was researched. The results show a decrease in the solution initial pH value, solution initial conductivity and E2initial concentration are beneficial to remove E2by DBDOW.An increase in the peak voltage can also improve the removal of E2. The effect of water properties on the removal of E2by DBDOW is also investigated by adding the standard solution of E2in tap water and landfill leachate. Solutions with higher impurities inhibit the removal of E2.The generation of organic acid and nitrate/nitrite ion in the reaction process leads to the decreasing of pH value in solution.Removal mechanism and reaction path of E2by DBDOW are also discussed. The comparison test by adding radical scavenger indicates that hydroxyl radical plays an important role in the removal of E2. The probable degradation path has been obtained using the six intermediate products of E2that were analized by LC-MS. By the ultraviolet full wavelength scanning and analysis of intermediate products, it can be seen that the hydroxyl phenolics in solution which can cause the estrogen activity were removed during the discharge process.