Design And Preparation Of New Functional Porous Materials For The Monitoring And Adsorption Removal Of Environmental Pollutants

The removal and detection of environmental pollutants are of great significance.However,the currently developed various methods for environmental pollutants removal and detection require a high cost and generally fail to satisfy the current need of human beings.These problems can be effectively solved by developing efficient sensor materials and adsorbent materials.Herein,metal-organic frameworks(MOFs)and covalent organic frameworks(COFs)are used to detect and remove environmental pollutants.Although the types of MOFs and COFs are diverse and complex,and they have the advantages of tunable structure and functional groups designability,most of the reported MOFs and COFs have poor chemical stability,which greatly limits the practical application of these porous materials.Therefore,in this thesis,a series of highly stable MOFs and COFs were designed and synthesized by developing new methods of material preparation and modification for specific separation systems and detection objects,and their performances of pollutants detection and adsorption separation were systematically studied.The main work is as follows:1.A strategy of highly efficient iodine capture was proposed by the formation of polyiodide induced by ionic liquid(IL).Ionic liquid with strong interaction towards iodine was incorporated into PCN-333(Al)with ultra-high porosity structure,therefore,the IL@MOF composites have both strong acting sites and the sufficiently large pore volume for iodine capture.The bromide ions of IL in the IL@MOF composites can be easily convert into polyiodide([I2nBr]-)with the neutral iodine molecules,and the resulting polyiodide anions can generate a strong coulomb force with the imidazole cation in IL,thus the IL@MOF composites have a strong force on iodine.In addition,the experiments show that the process of IL-induced formation of polyiodide is reversible,indicating that the obtained IL@MOF composites have an outstanding regeneration capacity for iodine adsorption.The experimental results show that the adsorption capacities of the IL@MOF composites are 7.35 g/g and 3.4 g/g in iodine vapor and iodine solution,respectively,which are better than all the reported iodine adsorbents.This work provides a general methodology for enhancing the interactions of neutral molecules and host materials,which may also be applied in other absorptive separation processes.2.The efficient detection and removal of antibiotics can be simultaneously realized by using the rigidifying-induced fluorescence enhancement and the adsorption-induced preconcentration effect.Herein,two ligands,phenamidine hydrochloride(PAHC)and diphenamidine hydrochloride(DPHC)were condensated with the AIE fluorescence ligands,4',4''',4''''',4''''''-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carbaldeh yde))(ETTC)to prepare two kinds of materials(F-CTF-1 and F-CTF-2)with different pore sizes.Because of skeleton rigidity,the AIE group is rigidified on the skeleton of the F-CTFs,thus the F-CTFs have higher fluorescence performance than the AIE ligand ETTC.The fluorescence detection experiments show that F-CTF-1 and F-CTF-2 have high sensitivity for nitrofurans(NFs)detection,and the limit of detection(LOD)of F-CTFs toward NFs are superior than any other reported sensor materials.Meanwhile,F-CTF-1 and F-CTF-2 have high selectivity for NFs detection in different antibiotics.In addition,the adsorption experiments exhibit that the NFs adsorption efficiencies of F-CTF-1 and F-CTF-2 are more than 99%.The results demonstrate that the F-CTFs can rapidly and effectively detect and remove NFs and exhibit great promising for practical application in water quality inspection,wastewater treatment and environmental remediation.3.Ultrathin fluorescent CTF nanosheet containing electron-deficient benzothiadiazole functional group was developed,and it realizes the selective detection of primary aromatic amines(PAAs)from various electron-rich amines.By utilizing anchoring and dilution effect,the benzothiadiazole unit with ACQ-effect,namely 4,4'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)dibenzaldehyde(BTDD)monomer,was successfully condensated with PAHC monomer to synthesize the F-CTF-3.Because of the anchoring and dilution effect,the BTDD fragments are evenly distributed in the 2D-CTF framework,therefore,F-CTF-3 has higher fluorescence quantum yield than BTDD monomer.More importantly,F-CTF-3 has excellent sensitivity,selectivity and regenerative properties for PAAs fluorescence detection.In addition,the mechanism study shows that the unique PAAs detection performances of the F-CTF-3 can be attributed to the static quenching process,which is confirmed by the formation of the ground-state fluorescence-quenched complex on account of the hydrogen bonding interactions between F-CTF-3 and PAAs.4.A new hydrophobic porous organic polymer(POP)with rich ether structure was developed,which is applied to coat the PU sponge for efficient oil-water separation.This superhydrophobic material,E-POP-1,is synthesized by condensation reaction of pentaerythritol(PET)and ETTC.E-POP-1@PU sponge was obtained by dipping E-POP-1 on a hydrophilic polyurethane sponge.The resulting E-POP-1@PU sponge has superhydrophobicity,high elasticity,strong mechanical stability and hierarchical porous structure,which are conducive to oil-water separation.The oil-water separation experiments show that the adsorption capacity of E-POP-1@PU sponge is 44-82 g/g for oil/organic solvent,and could basically maintain the original adsorption capacity after 100 adsorption recycles.In addition,the superhydrophobic E-POP-1@PU sponge can continuously adsorb and expulse oils and organic solvents from water surfaces with vacuum assistance.5.A novel high fluorescence COF with conjugated structure was developed for the selective antibiotics detection.By utilizing the base catalyzed aldol condensation,2,4,6-trimethyl-1,3,5-triazine(TT)and 5'-(4-formylphenyl)-2',4',6'-trimethyl-[1,1':3',1''-terphenyl]-4,4''-dicarbalde hyde(FTTD)were used to synthesize the COF with high fluorescence properties,namely F-COF-2.The characterization results show that F-COF-2 has strong fluorescence properties because of the conjugate structure formed between TT and FTTD during the synthesis process.The antibiotics fluorescence detection experiments show that the LOD values of F-COF-2 are 3.35 and 9.64 ppb for NFT and NZF,respectively,indicating that F-COF-2 has high sensitivity for NFT and NZF detection.Meanwhile,F-COF-2 has high selectivity and regeneration for NFT and NZF detection.The high sensitivity and selectivity properties of F-COF-2 toward NFT and NZF can be mainly attributed to the electron transfer and energy transfer between F-COF-2 with NFT and NZF.