Removal Of Trace Endocrine Disrupting Chemicals From Drinking Water

Endocrine disrupting chemicals (EDCs), also called environmental hormone, areknown as a class of chemicals which have xenobiotic and exogenous origins whilemimicking or inhibiting the natural action of the endocrine system in animals andhuman. Various adverse health effects of EDCs may be carcinogenesis, teratogenesis,mutagenesis and so on. In recent years, hermaphrodite has been reported in river or lakein our country, and so as to the detection of EDCs in part of drinking water sources.Therefore, it’s urgent to control EDCs actively, which is meaningful to our citizens’health.Clay is a mineral consisting of hydrous silicate of aluminum iron and magnesium.Most clay minerals exhibit a layered structures, the inorganic layer containingexchangeable ions, part of the surface atoms are activated on account of theirunsaturated valence-electron configuration. Due to the unique molecular structure andirregular crystal defects, silicate minerals are used to be adsorption material on domesticsewage and industrial wastewater treatment.The paper firstly studied on the extraction/enrichment method and HPLC methodfor EDCs determination, and secondly LC-MS method for carbamazepine(CBZ)determination. Then we chose and modified ceramicite, zeolite and quartz sand asadsorption material on EDCs control. And ceramicites modified bycetyltrimethylammonium bromide (CTMAB) were finally chosen for the study of EDCscontrol.In the adsorption studies, cationic/anionic surfactant(CTMAB/SDS) and ferrichydroxide were used for modified ceramicites, zeolites and quartz preparation. Originalor modified ceramicites and quartz were characterized by X-ray diffraction, BET-N2adsorption, FE-SEM and isoelectric point analysis. By static adsorption tests, westudied the adsorption property, regeneration capacity and influencing factors of naturalceramicites, CTMAB modified ceramictes, and studied the adsorption mechanism ofadsorption above. Finally, we studied the application of the clay minerals on EDCstreatment in drinking water, launched dynamic test of CBZ adsorption by orginal andorganic modified ceramicites filter column.The main conclusions of this work are drawn:1）The solid phase extraction for extraction and enrichment of EDCs showed goodrecoveries. The high performance liquid chromatography (HPLC) method for EDCs determination was studied with two mobile phases of100%methanol and0.5%phosphoric. The proposed HPLC metod provides a simple, rapid, precise quantitativeanalysis of EDCs in aqueous phase.Using100%methanol and0.1%formic acid as two mobile phases, and10,11-Dihydrocarbamazepine (DCBZ) as internal standard, the liquid chromatograph–mass spectrometer (LC-MS) method showed good detection results.2）Cationic surfactant CTMAB, anionic surfactant SDS, and ferric hydroxide underdifferent pH values (5,7,9) were used for modified ceramicites, zeolites and quartzpreparation. CTMAB modified ceramicites were found to be best modified material forEDCs adsorption. Because CTMAB could enhance polarity of ceramicites’ surface, andthus initiate electrostatic interaction, which finally promote the adsorption capacity topolar compounds. Compared to zeolites and quartz, ceramicites are the best adsorbentsfor EDCs. On the other side, the modified quartz preparation turned out to be failed dueto the low specific surface area and little adsorption sites of quartz on which modifierand EDCs can hardly be adsorbed.3）The adsorption process of EDCs on natural ceramicites and organic ceramiciteswere fast, and the adsorption reached equilibrium within5min. The adsorption processof EDCs on natural ceramicites is mainly caused by a physical process on the surface ofthe adsorbent, and on organic ceramicites is mainly due to distribution function becauseof the increase in hydrophobicity of organic ceramicites. Natural ceramicites andorganic ceramicites can respectively be regenerated with NaCl solution on neutral pHand used repeatedly. Organic ceramicites have high removal ability on EDCs and can beused to removing trace EDCs from drinking water.4）Dynamic test results showed that: Under the condition of2μg/L influentconcentration, the removal rates of CBZ in ceramic or organic modified ceramic filtercolumn were decreased with the regeneration times increase. The breakthrough time ofCBZ in modified ceramic filter column was24h, twice of that in ceramic filter column.The removal rates of CBZ of modified ceramics were most higher than originalceramics, with higher breakthrough point capacity and lower ceramic usage rate. Usingthe Thomas and Yoon-Nelson model to describe adsorption kinetics was failed topredict the breakthrough behavior of the bed, but only can simulate the rate constant andadsorption capacity.