The Preparation Of Covalent Organic Framework (COF-DhaTab) And Its Application In The Field Of Oil-water Separation

With the rapidly development of economy,the quantity demanded of resources by human beings is increasing,and the environmental pollution problem is becoming more and more serious.In particular,the frequent occurrence of various types of oil spills has caused tremendous damage to water and ecosystems.In order to protect ecological environment,the preparation and application of oil/water separation membranes and excellent oil-absorbing materials exhibit high society significance and practical value.Excellent oil-absorbing materials should have superhydrophobic/superoleophlic properties,high oil absorption ability and storage capacity.However,the present oil/water separation membranes and oil-absorbing materials have poor recyclability,oil/water separation performance,and low oil absorption ability,which limit their practical applications.In order to solve above problems,polyacrylonitrile(PAN)and melamine sponge(MS)were used as matrix materials,covalent organic framework(COF-DhaTab)and 1-iodo-1h,1h,2h,2h-perfluorooctanesulfonic grafted COFDhaTab(COF-DTF)as modifier to prepare PAN based oil/water separation membrane or modified MS(COF-DTF@sponge).The oil-absorbing ability of modified MS was significantly improved,while the oil/water separation ability,oil absorption ability and water repellency of PAN based membrane and the that of MS were all dramatically improved.The separation mechanism of the oil/water separation membrane and the adsorption mechanism of the oil-absorbing foam were respectively elaborated in two chapters:(1)PAN was used as the matrix and modified with COF-DhaTab to prepare oil/water separation membrane with high efficiency of oil/water separation.The experiment was performed by simple blending method and electrospinning.The infiltration of PAN nanaofiber membrane significantly changedas 3 wt.% of COFDhaTab was introduced.The surface of PAN based membrane switched from light hydrophobicity to amphipathicity in the air,superoleophobicity underwater,under-oil superhydrophobicity.The oil-in-water and water-in-oil emulsions can be efficiently separated by selective prewetting.The composite membrane maintains high flux while efficiently separating oil/water emulsions.The composite membrane also shows excellent antifouling properties and reusability.The preparation of intelligent oil/water separation nanofibrous membrane with excellent performance by simple blending of PAN and COF-DhaTab is a new way.(2)The infiltration of COF was regulated by grafting 1-iodine-1H,1H,2H,2Hperfluorooctane on the surface of COF-DhaTab.This superhydrophobic property can be applied to the field of oil/water separation.MS is an ideal adsorption substrate.By modifying COF,the superhydrophilic MS can be turned into a superhydrophobic /superhydrophobic foam(COF-DTF@sponge),which can be used as an efficient oilabsorbing material.The hydrophobicity of modified MS has been significantly improved,and the oil absorption capacity has also been enhanced.The highest adsorption capacity is 173.2 times of itself,and the adsorption speed is extremely fast,and the separation efficiency is up to 99.9%.The prepared COF-DTF@sponge has good recyclability for various oils.In addition,the COF-DTF particles can also be used to change the wettability of various matrix,such as nonwoven fabric,glass and cotton et al.