Construction And Performance Researching Of Metal-Organic Frameworks Paper-Based Composite Filter Adsorption Materials

With rapid industrialization and urbanization,environmental problems such as air pollution and water contamination have become increasingly severe,posing serious threats to human health and socioeconomic development.Research on personal protections and environmental remedy become very crucial.Metal organic frameworks(MOFs)have excellent adsorption and catalysis functions,and have great application prospects in the fields of air filtration and water pollution control.However,due to their powdery nature,MOFs need to be integrated with suitable substrates to create the applicable and shape-desired device in practical scenario.It is of great significance to study the combination of MOFs and the matrix as well as the properties of the resulting composite materials.Paper-based materials are flexible two-dimensional materials with good processability,which have already played an important role in the fields of air filtration and water treatment.Natural biomass paper-based functional materials(represented by cellulose paper)are green and renewable material,while high-performance paper-based materials(represented by aramid paper)have excellent mechanical performance and heat resistance.The integration of MOFs and paper-based materials would combine the virtues of both.Thus,the main work of this thesis is to explore the efficient combination of MOFs and paper-based materials and to evaluate the related properties of the resulting composite materials.The contents and conclusions are as follows:(1)MOFs nanocrystals were in situ synthesized in chitosan(CS)gel to prepare composite fillers,and the composite fillers were added into pulp and further transformed to composite paper-based materials.ZIF-8(zeolitic imidazolate framework-8)was used as a model to explore the in situ growth,MOFs-matrix integration,paper making process and properties related to air filtration.The results showed that ZIF-8 nanocrystals were successfully obtained in CS gel via in situ process,and the obtained ZIF-8 nanoparticles had smaller size than that of the direct hydrothermal method while kept similar yield.The retention rate of MOFs in composite paper-based materials reached 75.73%,which was significantly higher than the current mainstream methods such as direct filling or surface deposition.Studies on paper properties showed that combination of ZIF-8 nanoparticles and substrates were stable and the obtained paper-based materials exhibited good uniformity and strength.The composite paper-based materials also displayed good adsorption and filtration performance,which showed a filtration efficiency of 99.9%for PM2.5 with basis weight of 60 g/m2,and the filtration resistance can be effectively modulated by adjusting the basis weight.The antibacterial performance indicated that the composite paper had well inherited the photocatalytic antibacterial characteristic of ZIF-8.(2)The interaction between MOFs preparation and chitosan gelation were explored with gel block as a model.The results showed that the ligands had no significant impact on the gel structure while the metal ions played a decisive role in shaping the internal pore structure of the gel.Further studies were conducted on the dye adsorption performance,recycling performance,and photocatalytic degradation ability of the obtained ZIF-8/CS composites.The obtained block composite material had a good adsorption effect on methylene blue,and the adsorption process fitted the quasi-second-order kinetic equation and Langmuir isotherm.The removal rate of methylene blue could still reach 97.4%after five cycles of use,and the composite gel showed photocatalytic degradation ability under alkaline conditions.(3)The integration of MOFs and high-performance paper-based material was explored.MOFs nanocrystals were in situ synthesized in aramid nanofibers(ANFs)gels,and then transformed to MOFs-ANFs composite nanopaper materials.With ZIF-8 as a model,the morphology,gas adsorption capacity,thermal stability,dye adsorption and recycling performance of composite nanopaper were studied.The results showed that ZIF-8 nanocrystals were synthesized by in situ in ANFs gels,and well incorporated in the resulted composite nanopaper.The composite nanopaper had good thermal stability and excellent dye adsorption ability in high-temperature solutions.The adsorption process fitted to the quasi-second-order kinetic equation and Langmuir isotherm.The adsorption rate at 60℃ was higher than 30℃,and the maximum adsorption amount was not affected by high temperature.The ZIF-8-ANFs composite nanopaper was also recyclable,with the MB removal rate of 88%after five cycles of use.The strategy proposed in this thesis efficient and facile combination of MOFs and paper-based materials,striving to develop efficient and integrated MOFs materials for environmental remediation and ultimately contributing to human health and social development.