Preparation And Properties Of Cellulose Nanofibers And Metal-organic Framework Composite Membranes

Among the natural polymer materials in nature,cellulose has become the raw material of many environmental protection materials because of its wide range of sources and biodegradable advantages.In recent years,air pollution has been paid more and more attention,the formaldehyde and the haze of PM2.5 in the house decoration are the most deadly pollution sources in the room.With the acceleration of the structure of the urbanization,the shortage of fresh water resources needs to be solved urgently.And the use of the solar energy to generate the water vapor is of great concern to many scientific research scholars in recent years due to the characteristics of non-consumption of electric energy and repeated utilization,especially,the carbon material has a wide application scene as a solar absorber.For indoor air pollution,we prepared a porous cellulose nanofiber?CNF?stringed HKUST-1 polyhedron membrane on stainless steel screen used as a window screen for air purification.The hierarchical porous structures of CNFs stringed HKUST-1 polyhedrons generate highly nanometer to micrometer pathways for fast air transportation but blocking PM2.5.The highly microporous cavities with open copper sites of HKUST-1 present efficient adsorption for formaldehyde.The optimal blocking efficiency for PM2.5 is above 95%for a long time,and the optimal adsorption capacity of formaldehyde is 113.36 mg·g^-1.Besides,Due to the hierarchical but highly porous and thin thickness?⁵?m?,CNFs stringed HKUST-1layer also demonstrates air flow rate of 4.6 cm·s^-11 under 200 Pa,which is enough for the indoor activity.For freshwater scarcity,we also prepared hierarchical porous carbon membranes?HPCM?,composing of carbon nanofiber stringed porous carbon polyhedrons layer anchored on a carbonized filter paper?CFP?,from a cellulose nanofiber?CNF?stringed metal organic framework?HKUST-1?polyhedrons thin film grown on a filter paper by thermal carbonization.The resulted HPCM with hierarchical porous structures demonstrates different hydrophilicity between the carbon nanofiber stringed porous carbon polyhedrons top layer and bottom CFP layer,which not only ensures enough water supply to surface layer but also prevents excessive bulk water contacting with evaporating surface of higher temperature.When used as solar absorber for solar vapor generation,this HPCM exhibits an optimal water evaporation rate of 1.33 kg·m^-2·h^-11 and photothermal conversion efficiency of 84.3%.