Preparation And Cooking Oil Fumes Filtration Performances Of Composite Nanofibrous Nonwovens With Superoleophilic Surface And Fluffy Structure

Cooking is an important part of people’s daily life,but the emission of cooking oil fume（COFs）not only endangers the atmospheric environment,but also seriously threatens human health,and has become the third largest“culprit”of air pollution.Traditional fiber filter materials can effectively capture some mixed aerosols in COFs,but there are some problems such as poor interception efficiency of fine particles,large filtration resistance and short service life.In order to achieve long-term high-efficiency and low-resistance capture of COFs,Polyester（PET）/Cellulose Acetate（CA）composite nanofiber nonwovens were prepared by electrospinning.Superoleophilic and fluffy composite nanofiber nonwovens were prepared by adjusting PET/CA blending ratio and functional modification.The wettability,thermal stability and oil fumes filtration performance of the fiber nonwovens were investigated.In order to effectively adsorb volatile organic compounds（VOCs）in COFs,β-cyclodextrin（β-CD）microspheres with good affinity for VOCs were introduced into nanofibers by electrospinning and electrostatic spray.The sprayed composite fiber felt showed superhydrophilicity,superoleophilicity and excellent mechanical properties.The capture properties of different components in COFs by composite fiber felt were investigated.A series of electrospun root-like fluffy composite nanofibrous films for efficient filtration of cooking fumes were synthesized using polyester（PET）/cellulose acetate（CA）co-solvent system with different mass ratios.The morphology,surface and interface wettability,thermal stability and cooking fume filtration performance of these obtained films were characterized and analyzed by SEM,contact angle tester,thermal gravimetric analyzer and automatic filter material test system.The results showed the nanofibrous composite film with 8:2 exhibited obvious root hair-like fluffy structure with a root tip diameter 100 nm,root cap diameter about300 nm,porosity 93.85%,bulk density 0.23 g/m³,and water contact angle 154°,respectively.Moreover,the composite membrane displayed short oil absorption time 2 s,decomposition temperature>300℃,cooking fume initial filtration efficiency 92%and initial filtration pressure drop36 Pa.The filtration efficiency still remained≥91%with slow and regular increase in filtration resistance even after being recycled 20 times.In order to further improve the filtration performance of COFs,we develop a bioinspired and vine-like PET/CA composite nanofibrous nonwovens that have advanced filtration performance and enhanced flame retardancy for removal of COFs via one-step co-electrospinning.Through tailoring the blending ratio of PET/CA and the addition of functional components,a dramatic enhancement in three aspects of COFs filtration efficiency,air permeability,and flame retardant property are observed.The resultant nanofibrous filters possess the integrated characteristics of 0.48μm small pore size,high porosity（94.75%）,low packing density（0.22 g/m³）,combined with desirable surface chemistry,resulting in high-efficiency COFs removal（>99.5%）,low air resistance（<70 Pa）and promising long-term COFs purification performance.In addition,the as-fabricated membranes exhibit superhydrophobicity（water contact angle of 154°）and superoleophilicity with the oil contact angle of 0°within 0.21 s.In order to realize the comprehensive purification of COFs,β-cylcodextrin（β-CD）microspheres with good adsorption properties for volatile organic gases（VOCs）were simultaneously introduced into nanofibers by combining electrospinning and electrostatic spray,and composite fiber nonwovens with“irregular honeycomb”structure and uniform structure were prepared.Two kinds of composite fiber nonwovens with different structures showed superhydrophilicity and superoleophilicity.Among them,the irregular honeycomb composite fiber nonwovens showed the best oil wetting time of 0.05 s.The oil adsorption capacity of the two fiber mats was 92.64 g/g and 86.89 g/g,respectively,which were much higher than those of commercial oil-absorbing materials.In the filtration test,the irregular honeycomb composite fiber obtained the best filtration quality factor Q_fof 1.001 Pa^-1.In the real soot purification test,the prepared composite membrane material showed a much higher purification efficiency（>99%）than the commercially available soot filter material,and the purification efficiency after 120 min cycle purification was equal to the initial efficiency（>99%）.It has the potential for long-term effective use and can be widely used in air filtration,oil and gas separation and other fields.