Preparation Of Bimetal MOF-derived Carbon Materials And Fluorine-containing MOF And Their Applications In Environmental Analysis

Bisphenol compounds and perfluorinated compounds are two kinds of organic pollutants widely existing in environmental samples,have biological toxicity that can badly affect people's health.Therefore,the monitoring and determination of these two kinds of pollutants have caused widespread concern,and it is extremely urgent to develop a sensitive and selective analysis and detection method.Due to the wide distribution and low abundance of these two substances in the environment,also the composition of the sample matrix is complex,which can disturb the detection of target,so it is necessary to pretreat the samples before the analysis and determination.This work aims to develop novel MOF and its derived carbon material with good adsorption capacity,and use them in the enrichment of bisphenol compounds and perfluorinated compounds.Based on pretreatment with these materials as absorbents,coupled with HPLC or GC-MS,the high sensitivity methods for the determination of trace target analytes in environmental samples were established.This article mainly includes the following four aspects:Chapter 1:Introduction.This chapter mainly introduced the content of four aspects.First,it introduces that sample pretreatment is an important step in environmental analysis,and several sample pretreatment methods are described.Secondly,the preparation and application of MOFs are introduced.Then the MOFs derived carbon materials and their applications are introduced.At last,the basis and content of this article have been briefly expounded.Chapter 2:Preparation and characterization of magnetic nanoporous carbon derived from Zn-Fe bimetallic-organic framework.The 2-methyl imidazole was used as ligand,Zn(II)and Fe(II)ions as the coordination center,three bimetallic ZIFs with different Zn-Fe ratios(Zn-Fe-ZIF-X,X-10,20,50)have been successful prepared.The prepared bimetallic ZIF was used as templates,at temperature of 900? under nitrogen atmosphere it was carbonized to in situ synthesis the magnetic nanoporous carbon.It is known from the comparison that the MNPC prepared from Zn-Fe-ZIF-20 has higher specific surface area and more uniform the pore diameter distribution.Thus Zn-Fe-ZIF-20 was used as the template to prepare subsequent Zn-Fe-ZIF-NPC after aggregation with furfuryl alcohol(FA)which was used as the secondary carbon source.The prepared Zn-Fe-ZIF-NPC have a certain crystal shape,with the specific surface area of 577.64 m2 g-1,which has a good application prospect in the field of adsorption and separation.Chapter 3:Enrichment and separation of BPs in environmental water samples by using magnetic nanoporous carbon derived from Zn-Fe bimetallic organic frameworkThe magnetic nanoporous carbon(Zn-Fe-ZIF-NPC)derived from Zn-Fe bimetallic ZIF was used for magnetic solid phase extraction of four bisphenol analogs(BPs)(bisphenol A,bisphenol AF,bisphenol S and tetrabromobisphenol A),combined with high performance liquid chromatography(HPLC)to detect the targets in environmental water samples.Under optimal experimental conditions,the Zn-Fe-ZIF-NPC exhibits excellent adsorption performance for BPs.The maximum adsorption capacity achieved 439.0 mg g"1 for bisphenol AF,423.7 mg g-1 for bisphenol S,330.4 mg g-1 for tetrabromobisphenol A and 252.5 mg g-1 for bisphenol A.A sensitive magnetic solid-phase extraction with magnetic Zn-Fe-ZIF-NPC as adsorbent coupled with HPLC-UV analytical method was developed for the detection of trace BPs.A good linearity was shown in the range of 0.25-10 ng mL-1 with the correlation coefficient R as 0.996-0.998.The LODs were 0.03-0.07 ng mL-1 and the LOQs were 0.11-0.24 ng mL-1.This method was applied to detection of four BPs in environmental water samples and the satisfactory results were obtained.The recoveries obtained were in range of 93.0-110.7% with the RSDs of less than 4.6%,suggesting that the developed method could effectively enrichment and sensitively detection of trace BPs in water samples.Chapter 4:Preparation of fluorinated metal-organic framework and enrichment of perfluorooctanoic acid in environmental water samples.A novel fluorinated metal-organic framework(F-MOF)was prepared by using solvent-thermal method with tetrafluoroterephthalic acid(H2tfbdc)as ligand and Zn(II)as the central metal ion.A variety of characterization methods were used to determine the structure,morphology and specific surface area of the material.It can be seen that the material presents lamellar shape and has a certain crystal shape,with specific surface area of 44 m2 g-1.The prepared F-MOF was used as adsorbent for dispersive solid-phase extraction of perfluorooctanoic acid(PFOA).Under optimal conditions,the maximum adsorption capacity of PFOA was 419.77 mg g-1.Coupled with the GC-MS analytical method to detect PFOA in environmental water samples,the linear range was 0.05-25 ?g L-1 with the correlation coefficient R as 0.9991,the LOD was 2.6 ng L-1 and LOQ was 8.7 ng L-1.The established method was applied to the detection of PFOA in three environmental water samples,and satisfactory results were obtained.The recoveries obtained were 82.1-107.8%with RSDs less than 6.6%,which could meet the requirement of detecting trace perfluorooctanoic acid in environmental samples.