Research On Synthesis And Properties Of Superwettability Oil-water Separation Materials

As industrialization accelerates and resource and environmental problems become increasingly prominent,oil-water separation has become one of the key technologies to promote the efficient utilization of resources and improve the ecological environment.Porous materials with superwetting property show remarkable performance over conventional oil-water separation methods and become an ideal solution to realize efficient,convenient,and green oil-water separation.However,the tedious preparation method,severe application environment and complex oil-water properties limit the separation effect and popular application of superwetting materials.Meanwhile,in the face of different oil-water separation demands,there is a lack of universal countermeasures,and there is an urgent requirement to design and construct efficient and accurate superwetting oil-water separation materials for specific oil-water separation application scenarios.Therefore,this study is oriented to the preparation of simple,flexible,and suitable for large-scale production of superwetting materials,and to the practical problems of oil-water separation such as viscous oil-water separation,marine oil cleanup,residual trace water removal,etc.From two perspectives of surface chemical group regulation and microscopic pore structure optimization,superhydrophobicsuperoleophilic and superhydrophilic-superhydrophobic nanoparticle coatings are prepared,and superhydrophobic and superhydrophobic aerogels with directional pore structures are constructed.These superwetting materials implemented efficient,fast,and convenient oil-water separation for viscous oil-water mixtures,viscous oil spills and micron-sized water droplets,which provided significant theoretical support for the design,preparation,and application of superwetting oil-water separation materials.The results showed that n-octyltriethoxysilane hydrophobically modified silica nanoparticles could be simply and rapidly coated on the surfaces of various materials such as paperboard,iron plate and non-woven fabrics to form superhydrophobicsuperoleophilic coatings based on the air spray method.The superhydrophobicsuperoleophilic surface showed excellent oil-water separation ability for oil-water mixed liquids with oil phase density greater than water and low-viscosity water-in-oil emulsions,with separation efficiencies of 99.5% and 97.4%,respectively.However,the surface was ineffective in separating oil-water mixed systems with higher viscosity.Inspired by the trunk conduit structure,superhydrophobic-superoleophilic aerogels with directional pore structure were prepared based on hydrophobic silica nanoparticlepolyurethane-cellulose nanofiber suspensions by single-step freezing of ice templates.Due to the excellent oil-water recognition ability and unique pore structure,the aerogel has the properties of low flow resistance,fast absorption speed and large absorption capacity,and can implement autonomous cleanup of crude oil with viscosity up to78957.5 m Pa?s on water surface within 48 hours,which provides a new approach to solve the problem of high viscosity crude oil spill on water surface.In addition,the method can regulate the shape and size of aerogel according to the actual demand,and has the potential of large-scale production.Based on the synergy between different types of surface chemical groups,the hydrophilic sodium carboxylate group and the oleophobic carbon fluoride long chain were introduced sequentially on the surface of ball-milled roughened microcrystalline cellulose particles through the selective oxidation reaction of 2,2,6,6-tetramethylpiperidine oxide and the modification of perfluorooctanoic acid to achieve the effective combination of superhydrophilic and superoleophobic.The results showed that the superhydrophilic-superoleophobic coating prepared by air spraying can recognize oil and water quickly without any pretreatment operation,and maintain stable oil-water selectivity under acid-base,abrasion,and high temperature conditions.The superhydrophilic-superhydrophobic surface can effectively address the separation challenges of highly viscous oil-water mixtures,with separation efficiencies of more than96.8% for acid/alkaline oil-water mixtures,crude oil-water mixtures,highly viscous oilwater mixtures,and oil-water emulsions.The superhydrophilic aerogel with directional pore structure was prepared based on cellulose nanofiber-polyurethane elastomer suspension by using ice template single-step freezing method.The results showed that the internal pores of the aerogel could open and close with external force under the synergistic effect of the directional pore structure and superhydrophilicity,which effectively promoted the movement,aggregation,and absorption of micron-sized water droplets in viscous oil.Based on these results,an aerogel-peristaltic pump continuous micron-sized water removal device was designed and developed,and the continuous and efficient removal of micron-sized water droplets from highly viscous oil was achieved by alternate compression and release of the device,with a removal efficiency of 99.8%.