Preparation And The Dye Removal Properties Of Magnetic MOF-199@PP Melt-blown Nonwoven Composites

Polypropylene(PP)melt-blown nonwoven material is remarkable in both gas filtration and liquid filtration application due to its small pore size and high porosity.However,traditional PP melt-blown filter materials have been difficult to meet the requirements when they face increasingly complex environments.Therefore,the researches on functional modification of PP meltblown nonwovens have received extensive attention.Composite materials based on the modification by metal-organic framework materials(MOFs)are one of the research hotspots in the field of materials.Magnetic MOFs(MMOFs)have great potential in the fields of adsorption,separation and catalysis application in view of their advantages of high porosity,large specific surface area,high chemical activity and easy separation in magnetic field.Therefore,this paper firstly improved the complex preparation process of existing magnetic MOFs materials,and proposed a simple and easy-to-operate synthesis strategy.Then,MOF-199@PP melt-blown nonwoven composite was prepared by loading MOF-199 on the surface of PP meltblown nonwoven.The composition,structure and dye removal properties of MOF-199@PP melt-blown nonwoven composite were investigated.This work has potential value in term of the green synthesis of MMOFs materials and can drive the wider application of MMOF-based composites and functionalization of PP melt-blown nonwoven materials.Firstly,the amino-modified Fe3O4 was synthesized by the solvothermal method.After alkalization,Fe3O4/Cu(OH)2 was obtained and used as an intermediate to react with the organic ligand trimesic acid(H3BTC)to obtain Fe3O4/MOF-199 products.The composition and morphology of the obtained products at various stages of the preparation process were characterized by Fourier transform infrared spectroscopy(FTIR),X-ray diffraction(XRD)and scanning electron microscopy(SEM).The results indicated that Fe3O4/MOF-199 was successfully synthesized.The vibrating magnetometer test showed that Fe3O4/MOF-199 has superparamagnetism and a saturation magnetization of 31.2 emu/g,which present its excellent magnetic property.Nitrogen adsorption desorption test results showed that Fe3O4/MOF-199 was still a typical porous material,which inherits the high specific surface area and pore volume of MOF-199.Secondly,the magnetic MOF-199@PP melt-blown nonwoven composite was prepared by the immobilization of MOF-199 on the fiber surface of PP melt-blown nonwoven material after polydopamine(PDA)had been loaded on nonwoven material surface as the medium.The hydrophobicity,morphology and mechanical properties of the composite were characterized.The results showed that the PDA film was uniformly formed on the surface of PP fibers,which improves the surface inertness and hydrophobic properties of PP nonwoven material and provide functional groups for the immobilization of MOF-199.The presence of PDA film reduced the water contact angle of the PP melt-blown nonwoven material from 134.14° to 106.26°.XRD,FTIR and SEM results showed that MOF-199@PP melt-blown nonwoven composite material was successfully prepared,and MOF-199 was uniformly immobilized on the surface of PP fiber in the manner of the complete structure and uniform size.The mechanical properties of composite analysis results showed that the mechanical properties of the composite decreased compared to the unmodified PP melt-blown nonwoven material,and the longitudinal and transverse fracture stress decreases by 25.83% and 37.34%,respectively.Nextly,the removal performance of methylene blue(MB)by Fe3O4/MOF-199 was studied,and the effect of various solution conditions on MB removal efficiency was analyzed.The mechanism of the MB removal and the stability of the material after being used were also explored.Though the exploration of various factors influence on the MB removal performance,the conclusion was drew that the MB removal effect reach the optimum amount of 141.7 mg/g when Fe3O4/MOF-199 was 60 mg,had the concentration of MB solution was 100 mg/L,the initial pH is 4.0,and the addition amount of H2O2 is 90 ?L.The MB removal mechanism of Fe3O4/MOF-199 is the combination of adsorption and catalytic degradation.The performance and reusability of the magnetic MOF-199@PP melt-blown nonwoven composite under the optimal MB removal conditions were tested.For the composite,its first MB removal effect was excellent,however,the reusability needs to be further improved.