Pretreatment And Determination Of Organic Micropollutants In Water By Magnetic Nanocomposite Adsorption Materials

At present,with the rapid development of chemical,electronic engineering and agriculture,plant of organic pollutants are discharged into the water environment.And these organic pollutants can not only cause water pollution,but also pose a potential threaten to aquatic organisms and human health through the food chain.So it is important to detect the residual of organic pollutants in environmental water.However,because of the low concentration of organic micro-pollutants in the environmental water and the complex matrices which will cause serious interference,the water sample usually needs pretreatment before chromatographic analysis.MSPE is a new pretreatment technology developed in recent years based on magnetic adsorbent.And it is widely used in environmental analysis by the advantage of simple operation,high efficiency and less usage of organic solvents.According to the research of MSPE,magnetic adsorbent material is the key to improve extraction efficiency.Therefore,the development and synthesis of magnetic adsorbent materials with high selectivity and high adsorption capacity have become the focus of MSPE research.Based on this,three magnetic nanocomposite materials were synthesized and used as adsorbent respectively.Combined with chromatography technology,methods were built to detect different organic contaminants?QNs,EDCs and phenyl-OPs?in water samples.The main work of this research is as follows:1.The magnetic spheroidal material Fe₃O₄/SiO₂/NH₂ was synthesized by solvothermal and sol-gel method.The Fe₃O₄/SiO₂/NH₂-MSPE-HPLC method was established for the determination of three QNs?Levofloxacin Lactate,Enrofloxacin and Sparfloxacin?in water samples with the Fe₃O₄/Si O₂/NH₂ as adsorbent material.The experimental conditions of affecting the extraction efficiency were studied and optimized.And the results showed that the limit of detection?LODs?of this method was in the range of 0.03-0.1?g/L with recovery values ranging from 85.0-92.0%under optimized condition when the usage of Fe₃O₄/SiO₂/NH₂ is 15 mg,the extraction time is5 min,the usage of NaCl is 10 mg,1.5 mL methanol was used for desorption and desorption time is 5 min.It is confirmed that this method can be applied in residual detection of QNs in environmental water samples.2.The magnetic carbon adsorbent?Fe₃O₄/N-HCSC?with hollow core-shell structure was prepared by solvothermal and chemical coprecipitation method using resorcinol,formaldehyde solution and melamine.Besides,the investigations of adsorption kinetics and isotherm of Fe₃O₄/N-HCSC material on bisphenol A adsorption demonstrated that the adsorption process followed the pseudo-two order kinetic model and the Freundlich adsorption isotherm,respectively.And the four EDCs?triclosan,triclocarbon,bisphenol A and 2,2'6,6'-tetrabromobisphenol Adiallyl ether?were extracted by UAE-MSPE technology,and evaluated by HPLC analysis.Under the optimal experimental conditions,the LODs of Fe₃O₄/N-HCSC-UAE-MSPE-HPLC method ranged from 0.02-0.08?g/L,and the recoveries was in the range of88.0-92.0%with relative standard deviation?RSD?lower than 5.5%.It is indicated that the Fe₃O₄/N-HCSC material can be used as MSPE adsorbent for the extraction and analysis of EDCs in water sample.3.g-C₃N₄ was obtained by calcining the raw material melamine,and Fe₃O₄nanoparticles were further loaded on it to prepare g-C₃N₄/Fe₃O₄ magnetic material by chemical coprecipitation method,and the synethsized conditions were optimized.The morphology and structure were characterized by SEM and XRD respectively.The g-C₃N₄/Fe₃O₄ material was used as MSPE adsorbent combined with the GC to extract and detect three phenyl-OPs?Fipronil,Tebufenozide and Myclobutanil?from water sample.Under the optimal extraction conditions,good recoveries?84.1-92.3%?and low LODs?0.02-0.12?g/L?were obtained.