Preparation Of Metal-organic Framework Composites And Their Application In Determination Of Tetrabromobisphenol A And Its Analogs

Tetrabromobisphenol A（TBBPA）and its analogs are widely used in products,such as plastics and electronics,and enter the human body through various exposure pathways such as dust and diet and show health hazards effects such as reproductive toxicity and developmental toxicity.In 2021,the European Union suggested that TBBPA should be adopted in the list of restricted substances in Annex II of Ro HS instruction,and be required to carry out routine monitoring.However,at present,the detection of TBBPA pollutants not only relies on expensive mass spectrometry instruments but also is cumbersome and time-consuming,making it difficult to popularize and use in grassroots laboratories.The development of high-specificity,high-sensitivity,and low-cost analytical methods for TBBPA and its analogs is of great practical significance for routine environmental monitoring and decreasing the exposure risk.For complex environmental samples,metal-organic frameworks（MOFs）exhibit excellent catalytic performance and adsorption capacity,which can enhance the sensitivity of analytical methods.Molecularly imprinted polymers（MIPs）can fix the spatial conformation of the interaction between template molecules and functional monomers through organic polymerization and exhibit a specific recognition ability comparable to that of the antibody for targets.Multifunctional materials with high catalytic activity,specific recognition,and high adsorption capacity can be prepared by incorporating MOFs and MIPs.Based on these multifunctional materials,highly specific and sensitive,and low-cost determination methods for TBBPA and its analogs can be developed to serve routine monitoring and on-site analysis in grassroots laboratories.Based on this,in this study,zeolitic imidazolate framework-8（ZIF-8）composite was prepared and used as the thin film microextraction adsorbent for the simultaneous determination of five TBBPA and its analogs in the crayfish-aquaculture water system.On this basis,the MOFs-MIPs composites that have high catalytic activity and specific recognition ability were prepared and achieved on-site determination for single-component to three-component TBBPA and its analogs utilizing the simple colorimetric and fluorescent method.This study provided technical support for environmental monitoring and human health hazards research for TBBPA and its analogs through dust and diet.The content of this study was divided into three parts as follows:Chapter Ⅰ Preparation of ZIF-8/N-rGO composite and its application for determination of tetrabromobisphenol A and its analogs in crayfish-aquaculture water systemsObjective:ZIF-8/nitrogen-doped reduced graphene oxide（N-rGO）composite was prepared and thin film microextraction（TFME）-high-performance liquid chromatography（HPLC）method was developed for the determination of five TBBPA and its analogs in crayfish-aquaculture water systems and investigating the tissue distribution and bioaccumulative ability of these pollutants in crayfish.Methods:N-rGO was prepared by a hydrothermal method,and then ZIF-8/N-rGO composite was synthesized on the surface of N-rGO using zinc nitrate hexahydrate and2-methylimidazole as precursors.ZIF-8/N-rGO composite was coated on the nylon syringe filter by suction filtration under negative pressure to fabricate a TFME device.Based on characterization technologies and adsorption experiments,the adsorption performance and extraction mechanism of the ZIF-8/N-rGO composite were investigated.The parameters related to extraction efficiency were optimized,and a TFME-HPLC method was developed and further applied for the determination and bioaccumulative ability evaluation of five TBBPA and its analogs in crayfish-aquaculture water systems.Results:The adsorption capacities of ZIF-8/N-rGO composite for TBBPA and its analogs ranged from 50.98 to 107.45 mg g^-1.The good extraction efficiency for these compounds was attributed toπ-π,hydrophobic,and hydrogen bonding interactions.This method can be applied for the determination of five TBBPA and its analogs in crayfish-aquaculture water systems.The linearities were in a range of 0.1-100 ng m L^-1 and LODs ranged from 0.030 to 0.063 ng m L^-1.The spiked recoveries ranged from 89.4%to106.2%.Moreover,TBBPA and its analogs were mainly distributed in the viscera and head shell of crayfish,and the bioconcentration factors ranged from 0.25 to 19.20 L kg^-1,indicating that these contaminants were non-bioaccumulative in crayfish through aquaculture water exposure.Conclusions:ZIF-8/N-rGO composite showed good extraction performance for TBBPA and its analogs and can achieve the simultaneous determination of five TBBPA and its analogs in the complex environmental matrix.These pollutants were primarily distributed in the viscera and head shell and were non-bioaccumulative in crayfish through aquaculture water exposure.Chapter Ⅱ Preparation of HKUST-1/imprinted composite and its application for determination of tetrabromobisphenol AObjective:MIP/HKUST-1 paper-based composite that possessed specific recognition and peroxidase-like catalytic activity was prepared and a colorimetric determination method for trace TBBPA in dust samples was developed for highly sensitive and on-site analysis.Methods:HKUST-1 possessing peroxidase-like activity was modified on the surface of filter paper.Then,a multifunctional MIP/HKUST-1 paper-based composite was synthesized using TBBPA as a template,（3-aminopropyl）triethoxysilane as a functional monomer,and tetraethyl orthosilicate as a cross-linker.MIP/HKUST-1 paper-based composite was characterized using such as multiple technologies scanning electron microscopy（SEM）,fourier transform infrared（FTIR）spectroscopy,and X-ray photoelectron spectroscopy（XPS）.The selective recognition and catalytic mechanism of this composite were investigated by adsorption experiments.Under the optimized experiment conditions,the colorimetric method was developed for the determination of trace TBBPA in dust samples.Results:The maximum adsorption capacity of the MIP/HKUST-1 composite was187.30 mg g^-1,and the imprinting factor was 7.63,showing specific recognition ability for target molecules.The selective recognition of MIP for TBBPA can decrease the residue imprinted cavities and further reduce the peroxidase-like catalytic activity of HKUST-1under the MIP layer.Moreover,the adsorbed TBBPA can also accelerate the consumption of hydrogen peroxide（H₂O₂）as a substrate.Thus,H₂O₂ and HKUST-1 synergistically reduced the generation of 3,3’,5,5’-tetramethylbenzidine oxidation products.and achieve a highly sensitive colorimetric analysis of TBBPA.Based on the above strategy,a highly sensitive colorimetric method was developed for TBBPA.This analytical method can achieve the rapid determination of TBBPA in dust samples.The linearity ranged from 0.01to 10 ng g^-1 and the limit of detection（LOD）was 3 pg g^-1.The spiked recoveries ranged from 94.4%to 106.6%.The gray intensities caused by TBBPA analogs were<1%of that caused by TBBPA at the same concentration,implying excellent anti-interference ability.Conclusions:MIP/HKUST-1 composite exhibited high selective recognition and peroxidase-like catalytic ability and can be applied for the determination of trace TBBPA in dust samples,and had the advantages of low cost,easy operation,and on-site monitoring.Chapter Ⅲ Preparation of UiO-66-NH₂/imprinted composite and its application for determination of tetrabromobisphenol A and its analogsObjective:MIP/UiO-66-NH₂composite with specific recognition and the photocatalytic property was prepared and a simultaneous determination method for TBBPA,bisphenol A（BPA）,and tetrachlorobisphenol A（TCBPA）in dust was established by utilizing paper chromatography separation,molecular recognition and photocatalysis.Methods:MIP/UiO-66-NH₂ composite was prepared on filter paper using TBBPA as template molecules.This composite was characterized by multiple technologies,such as SEM and FTIR.Adsorption experiments were used to investigate the specific recognition performance.Based on the selective recognition of MIP,paper chromatographic separation,and photocatalytic activity of UiO-66-NH₂,a simultaneous fluorescence method was proposed for the determination of multi-component pollutants and the corresponding mechanism of fluorescent detection was investigated in detail.After the important parameters were optimized,this fluorescent method was applied for the simultaneous determination of TBBPA and its analogs in dust samples.Results:The maximum adsorption capacity of the MIP/UiO-66-NH₂ composite for TBBPA and its analogs was 120.94 mg g^-1 and the imprinting factor was 4.07.Under ultraviolet light irradiation,UiO-66-NH₂ possessing photocatalytic activity can produce reactive oxygen species（ROS）.TBBPA,TCBPA,or BPA that was selectively absorbed on MIP can decrease the photocatalytic property of MOFs and consume a portion of ROS at the same time,thus weakening the signal of the corresponding fluorescent probe H₂DCFDA.Moreover,utilizing paper chromatography separation,the simultaneous determination of three TBBPA and its analogs in a complex matrix was achieved.The linear range of this method was 0.5-1000 ng g^-1 and LOD was in a range of 0.14-0.30 ng g^-1.The spiked recoveries of real dust samples ranged from 91.0%to 105.6%.Conclusions:The paper-based analytical device based on MIP/HKUST-1 composite integrated recognition,separation,and detection,and possessed many advantages such as environmentally-friendliness,high sensitivity,low cost,and easy-to-fabrication.This method can achieve the simultaneous fluorescence determination of three TBBPA and its analogs in dust samples.