Study On The Preparation Of The Functionalized Porous Materials And Their Application In The Rapid Detection And Removal Of Tetrabromobisphenol A

Tetrabromobisphenol A（TBBPA）,the highest output of brominated flame retardant in the world,is widely used in electronic and electrical products,construction materials,and textiles.These products release TBBPA into the environment during production,use and disposal.TBBPA is currently reported to be detected in a variety of environmental media,such as water,soil,river substrate,and indoor dust.TBBPA has endocrine disrupting effects,reproductive toxicity,immunotoxicity and carcinogenic effects,and has been classified as a Group 2A carcinogen by the International Agency for Research on Cancer.Therefore,it is important to carry out research on the rapid detection technology and removal method of TBBPA to assess the status of TBBPA environmental pollution,promote environmental remediation and protect the health of the population.Mesoporous materials with low density,high specific surface area,and porosity are ideal nano-loading platforms and pollutant adsorbents.In this paper,rapid detection and removal method for TBBPA was developed based on dendritic mesoporous silica and covalent organic frameworks,respectively.The details of this study are as follows:Chapter 1:Preparation of dendritic mesoporous silica-quantum dots hybrid particles and evaluation of propertiesObjective:Using dendritic mesoporous silica（DSN）as a support platform,quantum dots（QDs）were embedded in the mesoporous structure of DSN by covalently bonding QDs to prepare DSN-QDs composites.Methods:DSN was prepared using cetyl pyridinium bromide as a soft template and tetraethyl silicate as a silicon source,followed by grafting 3-aminopropyltriethoxysilane.The Cd Te QDs were synthesized with mercaptosuccinic acid as a stabilizer,and the DSN-QDs composites were prepared by embedding the QDs into the porous structure of DSN through the reaction of amino and carboxyl groups under the catalytic effect of EDC/NHS.The DSN-QDs were characterized using transmission electron microscopy,X-ray photoelectron spectroscopy,fourier-transform infrared spectroscopy,and zeta potential analyzer.The quantum yield of DSN-QDs was examined by the reference method.And the stability of DSN-QDs was evaluated by storage time,different p H,and UV lamp irradiation.Results:Transmission electron microscopy images showed that DSN had a regular dendritic spherical structure.The surface area of the DSN was 485 m² g^-1 and typical pore sizes were 3 and 15 nm.The EDS energy spectrum,Fourier-transform infrared spectroscopy and fluorescence change results showed that QDs were successfully embedded into the porous structure of DSN.X-ray photoelectron spectroscopy elemental content analysis showed that the atomic percentage of QDs in DSN-QDs was 3.5%.The quantum yield of DSN-QDs was 58%,the fluorescence decreased less than 5%after 30days of storage,the fluorescence intensity was stable at p H 5-10,and the fluorescence intensity was more than 50%of the initial fluorescence value after 10 h of UV lamp irradiation.Conclusions:In this chapter,DSN-QDs composites were prepared by covalently bonding QDs and DSN.Using DSN as the loading platform,DSN-QDs showed high quantum yield and stability.Chapter 2:Preparation of molecularly imprinted polymers-capped dendritic silica-quantum dots hybrid particles and its application in rapid detection of Tetrabromobisphenol AObjective:We constructed a molecularly imprinted fluorescent probe for TBBPA detection in e-waste samples.Methods:A fluorescent sensor was developed for TBBPA detection based on molecularly imprinted polymers（MIPs）combined with DSN and Cd Te QDs hybrid particles.The MIPs were synthesized using TBBPA as a template,3-aminopropyl triethoxysilane as a functional monomer,and tetraethyl orthosilicate as a cross-linker.The porous structure of DSN not only provided an ideal loading platform for QDs embedding,but also provided support materials for surface imprinting.The preparation route was characterized using transmission electron microscopy,X-ray photoelectron spectroscopy,Fourier transform infrared spectroscopy,and zeta potential analyzerand.The adsorption capacity of DSN-QDs-MIPs was evaluated in detail.And this method was applied to detect trace TBBPA in spiked water and plastic e-waste samples.Results:The theoretical adsorption capacity of DSN-QDs-MIPs for TBBPA were96.5 mg g^-1 with an imprinting factor of 7.9.And DSN-QDs-MIPs was able to reach adsorption equilibrium within 10 min.Under optimal detection conditions,the fluorescence intensity（λex=340 nm,λem=605 nm）of DSN-QDs-MIPs were quenched in proportional to the concentration of TBBPA with a linear range of 0.025-5μM and a detection limit of 5.4 n M.The method is highly selective and resistant to interference,and the fluorescence intensity of DSN-QDs-MIPs decreased less than 5%after 20 days storage.The developed probes were successfully applied to the detection of TBBPA in spiked water samples and plastic e-waste samples,and the results of this method were consistent with those obtained using high performance liquid chromatography.Conclusions:In this study,a fluorescence detection method was developed for the detection of TBBPA using DSN as a nanoplantform,combined with QDs and surface molecular impringting.This method was applied to detect TBBPA in plastic e-waste samples successfully.Chapter 3:Preparation of two-dimensional covalent organic framework and its application to TBBPA removal in aqueous environmentObjective:A two-dimensional covalent organic framework（Tp Da-OH）containing hydroxyl groups was prepared and used as an adsorbent for the removal of TBBPA from aqueous solution.Methods:A two-dimensional covalent organic framework enriched with hydroxyl groups（Tp Da-OH）was prepared by a solvothermal method using 1,3,5-（4-aminophenyl）benzene and 2,5-dihydroxyterephthalaldehyde as structural monomers.Tp Da-OH was characterized using transmission electron microscopy,X-ray photoelectron spectroscopy,contact angle experiments,and nitrogen adsorption experiments.The adsorption performance,adsorption thermodynamics and adsorption kinetics of Tp Da-OH on TBBPA were investigated by static and dynamic adsorption experiments.The interference of p H,humic acid and ionic strength were examined,and the practical application and reusability of the materials were evaluated.In addition,the adsorption mechanism was also explored.Results:Tp Da-OH possessed a two-dimensional mesoporous structure with a specific surface area of 860.2 m² g^-1 and a pore size of 2.4 nm.The theoretical adsorption capacity of Tp Da-OH on TBBPA was 675.8 mg g^-1,which was consistent with the multilayer adsorption model.And the adsorption process was an exothermic process that took place spontaneously.The dynamic adsorption process conformed to the pseudo-secondary kinetic model.The adsorption capacity of Tp Da-OH on TBBPA was not disturbed at different p H（3-8）,humic acid concentration(0-50 mg L^-1)and Na Cl concentration(0-500 mg L^-1).In TBBPA removal applications in pure water,lake water and river water,the removal rate was greater than 95%,and the performance degradation was less than 5%after 6 times of repeated use.The main forces for the adsorption of TBBPA on Tp Da-OH areπ-πand hydrogen bonding interactions.Conclusions:Tp Da-OH is a good adsorbent for the removal of TBBPA in aqueous environment with high adsorption capacity,short equilibrium time,high interference resistance and reusability,and it can be used for the removal of TBBPA from actual water samples.