Study On Preparation And Oil-in-water Emulsions Separation Properties Of Underwater Superoleophobic Materials

With the rapid development of society,a large number of emulsified oily wastewater has been produced in petrochemical,food,textile,leather,steel,metal processing and other industries.The massive discharge of the oily wastewater has caused serious harm to the environment and human health.Nowadays,superhydrophilic/underwater superhydrophobic membrane materials can effectively separate emulsified oil-containing wastewater while maintaining good self-cleaning,which is a current research hotspot in the field of oil-water separation.The superhydrophilic/underwater superhydrophobic membrane materials prepared by electrospinning technology have become one of the most effective methods for oil-water separation due to their higher porosity and larger specific surface area.But nowadays,most of the electrospinning membrane materials still have poor hydrophilicity,which is easy to cause membrane fouling.So,it is difficult to separate oil-water mixtures with relatively high viscosity,especially stable crude oil-in-water emulsions.Therefore,it is still an urgent problem to improve the hydrophilicity of electrospun membrane to reduce membrane pollution and further improve the separation performance of membrane materials.In addition,most superhydrophilic/underwater superoleophobic materials have some problems such as complex preparation processes,high cost and so on.All these have greatly limited the application prospects of superhydrophilic/underwater superoleophobic materials.Based on this,several kinds of underwater superoleophobic materials were prepared by simple and effective methods,and their separation properties of oil-in-water emulsions were studied.The main contents as follow:1.Palygorskite and polyacrylonitrile?PAN?were used as raw materials.The palygorskite-coated PAN nanofiber membranes with superhydrophilicity/underwater superoleophobicity were prepared by electrospinning technology and vacuum suction filtration assembly method.Among them,palygorskite coating can effectively prevent oil droplets from polluting the bottom PAN nanofiber membrane due to its strong water absorption and water retention.The as-prepared membranes can effectively separate a series of oil-in-water emulsions including surfactant-stabilized crude oil-in-water emulsion?>99%?.In addition,it can maintain a good separation effect in the cycle separation experiment.2.Using electrospinning technology and ZIF-8 as sacrificial template,the PAN nanofiber membrane with superhydrophilicity/underwater superoleophobicity was prepared by chemical modification,which showed extremely low adhesion for crude oil underwater.The as-prepared PAN nanofiber membrane exhibited extremely low adhesion to crude oil underwater,which can be employed to efficiently separate a series of oil-in-water emulsions,especially surfactant-stabilized crude oil-in-water emulsion with separation efficiency above 98.9%,and has a high separation flux(>1100 L·m^-2·h^-1)and better cycle stability.3.A simple and universal method was designed,which used a variety of hydrophilic materials for simple stacking to prepare a kind of bed with“sandwich”structure.The as-prepared bed showed excellent underwater superoleophobicity.It has been successfully applied to the separation of surfactant-stabilized oil-in-water emulsions with high separation efficiency?>99.6%?and good cycle stability.