| With the rapid development of our country,the pollution is becoming more and more serious,especially the polycyclic aromatic hydrocarbons(PAHs)in water.PAHs posses some ill effects for ecological environment and human health.Therefore,the prevention and detection of PAHs in environment is becoming the most important work in the environmental protection.Supporting ionic liquids on the solid materials combines the advantages of both materials and ionic liquids,and thus has been widely used in the fields of chemical industry and other fields in recent years.In this paper,three kinds of alkyl imidazole ionic liquids were synthesized,and three functional materials were prepared by modifying those ionic liquids to the surface of silica gel respectively.After that,those functional materials were prepared into solid phase extraction columns for the extraction of PAHs in water.The researching are as follows:(1)Two kinds of ionic liquids,1-hexadelyl-3-triethoxy propylsilyl-imidazolium bromide([HDTIm]Br)and 1-octadecyl-3-triethoxy propylsilyl-imidazolium bromide([ODTIm]Br),which possessed siloxy were synthesized via the "one step synthesis" method under the protection of nitrogen.Subsequently,we used[HDTIm]Br as material for the peparation of another ionic liquid,1-hexadecyl-3-triethoxy propylsilyl-imidazolium tetrafluoroborate([HDTIm]BF4),by anion exchange reaction.The structures of those ionic liquids were characterized by NMR,FTIR and EA,and the results showed that the target ionic liquids were successfully synthesized.(2)In this study,the three ionic liquids were successfully bonded to the surface of silica gel for the high reaction activity of siloxy group.Thus three novel functionalized materials,including[HDTIm]Br-SiO2,[ODTIm]Br-SiO2 and[HDTIm]BF4-SiO2 were prepared.The materials were characterized by FTIR,TG,BET and SEM.The results showed that those ionic liquids were successfully modified to the surface of the silica gel.(3)Those functionalized materials were prepared into solid phase extraction(SPE)columns for the adsorption of PAHs in water.In this work,an analysis method combining High Performance Liquid Chromatography and Fluorescence Detection technology(HPLC-FLD)was established for the determination of 15 PAHs.The parameters including types of eluent,the amount of eluent and the flow rate of elution were optimized.The results showed that the three SPE materials had good concentration effect for the extraction of PHAs except naphthalene,and the average recoveries were in the range of 60%to 120%.In general,to the material[HDTIm]Br-SiO2,the effect of acetonitrile elution was good,while ethyl acetate was better for the material of[ODTIm]Br-SiO2 and[HDTIm]BF4-SiO2.And all the materials showed good performance with the best dosage of 10 mL eluting agent,and the elution rate 1 mL/min.(4)The enrichment effect of the three kinds of materials for PAHs in Xihu and Muye water of Xinxiang was investigated under the optimal conditions.Low cyclic PAHs were detected.PAHs had satisfactory recoveries and relative standard deviations were less than 10%except naphthalene.In this study,the enrichment effects of those materials for PAHs were also compared.It was found that for the PAHs with high number of rings,the adsorption capacity of[ODTIm]Br-SiO2 with long carbon chain was better,while for PAHs with low number of rings,[HDTIm]Br-SiO2 showed better adsorption.At the same time,compared with the adsorption properties of[HDTIm]Br-SiO2 and[HDTIm]BF4-SiO2,the more lipophilic[HDTIm]BF4-SiO2 had better adsorption effect on the high ring number of PAHs. |
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