Study On The Models And Mechanisms Of The Enhanced Adsorption And Biodegradation Of Multiple Endocrine Disrupting Compounds In Soil

Endocrine disrupting compounds (EDCs) were a kind of compound, which disrupted wildlife’s reproductive system by imitating and blocking the activity of natural hormones. Estrone (E1), estradiol (E2), and estriol (E3) were mainly from the secretion of animals, and it reversed the sex of animals even at low concentrations (μg/L). Both of17a-ethinylestradiol (EE2) and bisphenol A (BPA) were the synthetic EDCs, which were applied in industry, livestock, medicine and pharmacy industry. EE2was commonly used in livestock’s feed, oral contraceptive and hormone drugs, which reduced animal’s reproductive capacity and progeny even at ng/L level. Bisphenol A (BPA) was used in chemical industry for the production of synthetic plasticiser and food package, and expressed estrogen effect on human and animal’s endocrinium at trace level. The residual EDCs will be found in water, soil, and sediment in different degree after enter environment. The previous studies mainly focused on the behaviour and transport of EDCs in water, but little in soil. The soil was an important place of EDCs’migration and accumulation. Therefore, the control and removal of EDCs in soil was the research point in the study.The E1, E2, EE2, E3and BPA were selected as target pollution, and soil was the research environment. The dispersive liquid-liquid microextraction-solidification of floating organic drop-high performance liquid chromatography (DLLME-SFO-HPLC) and ultrasonic assisted-surfactant enhanced emulsification microextraction-precolmn derivation-high performance liquid chromatography (UAE-SEEME-PD-HPLC) were estalished, respectively. The result indicated that UAE-SEEME-PD-HPLC was an environmental friendly method without dispersive agent (toxic solvent). Meanwhile, UAE-SEEME-PD-HPLC was more sensitive for determination of trace EDCs. The linear range of E3, BPA, EE2and E2were0.02～2.0mg/L, while NP was0.02-1.0mg/L, and the correlation coefficients were ranged of0.9950～0.9999. The limits of detection were1.06μg/L (E3),2.22μg/L (BPA),3.55μg/L (EE2),3.41μg/L (E2) and5.04μg/L (NP), respectively. The spiked recoveries of estrogens under different spiked levels (0.02,0.20and1.00mg/L) for estrogens were88.08～117.33%, with the relative standard deviation (RSD) were0.75～9.73%. Therefore, UAE-SEEME-PD-HPLC was chosen for analyzing the EDCs in water-soil system.Based on the adsorption behaviour of EDCs in soil, the quantitative structure-property relationship (QSPR) was employed for analyzing the mechanism of EDCs’ unitary and binary interference adsorption in soil. The differences of EDCs adsorption capacity and the selectivity of soil in multiple systems were investigated by angle calculation method and partition coefficient of soil, respectively. The results showed that the adsorption differences of EDCs were dominanted by Connolly solvent excluded volume (CSEV), polarisability, and some other topological structure parameters of EDCs molecular. The developed QSPR models were helpful to reveal the mechanism of multiple EDCs. EDCs in E2-EE2-BPA system presented a superior selectivity of sediment with the (3of43.48～87.86, which suggested the high selectivity of soil for EDCs. The order of sediment selectivity (E1>EE2>E2>E3>BPA) in binary system was agreed with EDCs’adsorption capacity, which suggested the adsorption was dominated by partition adsorption. The result sugguested the adsorption of EDCs in soil was not only depended on the physicochemical property of EDCs, but also the selectivity of soil.In the study of enhanced adsorption of multiple EDCs onto soil, a factorial design was employed for opitmizing the conditions of EDCs adsorption onto MnO2. soil. The liquid phase-mass spectrometry (LC-MS) were ultilized for the analyzing the adsorption mechanism and degradation products of EDCs onto MnO2; in the study of enchanced biodegradation of EDCs in soil, a BP neural network and factorial design were combined for condition optimization (amount of carbon source, amount of nitrogen source and ultrasonic time), and the mechanism of biodegradation differences were explained. The results showed that the optimized conditions of EDCs adsorption onto the soil doped with MnO2were:0.1g of soil quality,0of ionic strength, without control pH (pH=8.0for E2, pH=3.8for E3),5.0mg/L of EDCs concentration, and15%of MnO2doping ratio; the removal rate of E1, E2, EE2, E3and BPA were all above on90%, the adsorption progress of EDCs onto was the soil doped with MnO2was the dominated by physical absorption and chemical degradation, simultaneously. The correlation coefficient and Nash-Suttclife coefficient values (NSC) of BP neural network model were in the range of0.90-1, which indicated the accuracy prediction of models. The maximum degradation rates of E1, E2, EE2, E3and BPA were53.95%,65.43%,87.13%,20.47and69.27%, respectively. The optimum conditions for degradation were as follow:10%of carbon source,10%of nitrogen source,20mL of inoculum dose,1min of ultrasonic time, and168h of degradation time. The biodegradation differences analysis showed the degradation rate of E1, E2, EE2, E3and BPA were proportional to mobility of EDCs, while inversely proportional to the persistence of EDCs.Finally, the sodium alginate, calcium alginate and rhamnolipid were spiked into the soil to enhance the biodegradation with ultrasoni-assistant. Central composite design was ultilized for the optimizaiton of biodegradation conditions of EDCs in soil. The biodegradation differences mechanism of EDCs in soil was analyzed by experimental results and quantitative structure-biodegradability relationship (QSBR), which was from the perspective of external and internal reason. The results suggested that the addition of rhamnolipid with ultrasoni-assistant achieved the best removal of EDCs, and the biodegradation rate of E1, E3, BPA, EE2and E2was100%,94.56%,94.56%,94.90%and94.86%, respectively. The suitable ultrasonic time would promote the biodegadation rate of EDCs in soil; on the contrary, both of long or short ultrasonic time would inhibit the degradation efficiency of pseudomonas putida. The sodium alginate and calcium alginate could fix the free pseudomonas putida in an area, and which was benefit for the growth and stability of pseudomonas putida. Meanwhile, the degradation of EDCs dominanted by polar surface area (PSA). For the enhaced biodegradation by rhamnolipid with ultrasoni-assistant, the surface tension above on the critical micelle concentration (CMC) was obviously enhanced the degradation of EDCs, and the interaction of PSA*surface tension performed an antagonism effect on the degradation of EDCs.