Preparation And Its Properties Of MOFs/Cotton Pulp Fiber Composites By In-Situ Growth Method

Metal-organic frameworks（MOFs）have been extensively applied in the fields such as oil-water separation,fluorescence and anti-bacteria due to their advantages like simple preparation,great specific surface area,structural diversity and modifiable framework scale.However,the single MOFs crystal is associated with the problems such as susceptibility to aggregation and difficulty in powder collection,which affects the excellent performance of MOFs crystals and hinders the further application of MOFs.At present,some studies use the matrix pretreated by acid and alkali to compound with MOFs through blending,hot pressing,deposition,electrospinning and hydrothermal synthesis to solve the problems mentioned above.Such a synthesis method may cause the MOFs crystals to be encapsulated in the matrix or the bonding between the matrix and the MOFs material is unstable,which affects the effective utilization of the active sites of the MOFs,and even causes the MOFs crystals to fall off the matrix.The surface of plant fiber contains a large number of active groups,which can provide MOFs with active sites for in-situ growth without pretreatment,so that MOFs can grow stably and uniformly on the surface of the fiber,and overcome the problems of MOFs being encapsulated and unstable in combination with other matrix materials.At the same time,plant fiber also has the advantages of low price,wide sources,degradability,and easy processing and molding,making it a good base material for MOFs modification.In this paper,plant fiber-cotton pulp fiber is used as the matrix,and three kinds of MOFs/cotton pulp fiber composite materials with different properties are synthesized through hydrothermal synthesis and static aging.Furthermore,to characterize its morphology,structure and performance to study its potential application value.The following researches have been carried out around the above purpose:（1）UiO-66/fiber composites were prepared by hydrothermal synthesis.UiO-66/fiber composite material modified with octadecylphosphonic acid（OPA）was used to introduce hydrophobic alkyl chains on its surface to synthesize OPA-UiO-66/fiber composite material.The results showed that UiO-66 was grown in situ on the surface of cotton pulp fibers,and UiO-66/fiber composite material has hydrophobic and lipophilic properties after OPA modification.OPA-UiO-66/fiber composite material can quickly separate water-in-oil emulsions driven by gravity,with a separation efficiency of up to 99%.After the composite material was recycled 10 times,its separation efficiency for water-in-oil emulsions remained above 97%.（2）UiO-NDC/fiber composites were prepared by hydrothermal synthesis.Based on the functional properties of UiO-NDC,the fluorescence sensing properties of the composites to metal ions were studied.The results show that UiO-NDC crystals exhibit an octahedral-like configuration and grow in situ on the surface of cotton pulp fibers.UiO-NDC/fiber composites can emit stronger fluorescence at an excitation wavelength of 365 nm than cotton pulp fibers.Based on the absorption competition quenching mechanism,within the range of Fe³⁺ion concentration of 0.010-0.100 m M,the linear relationship between the fluorescence intensity of the UiO-NDC/fiber composite material and the Fe³⁺ion concentration can be used to quantitatively detect Fe³⁺ions.（3）The ZIF-67/fiber composite material was prepared by the method of standing aging.The results showed that ZIF-67 crystals had a regular rhombic dodecahedron configuration and were grown in situ on the surface of cotton pulp fibers.After ZIF-67 loading,the specific surface area of ZIF-67/fiber composites increased by about 80 times compared to cotton pulp fibers.The ZIF-67/fiber composites have antibacterial properties,and the antibacterial properties against Escherichia coli and Staphylococcus aureus are positively correlated with the loading of ZIF-67.Therefore,the antibacterial effect of ZIF-67/fiber composites can be controlled by regulating the loading of ZIF-67.