Preparation Of Amidoximated PAN-based Composite Fiber Membrane And Study On Its Oil-water Separation Performance

In recent years,with the improvement of human living standards,the discharge of oily sewage from machinery manufacturing,food processing,textile and catering industries has directly led to increasingly severe oil pollution in water resources.After the oily sewage enters the human body,it will damage the human circulatory,nervous,blood system,and cause harm to the human body.The hydrocarbons in the oil can destroy the structure of biological cell membranes,and have chemically toxic to organisms,which seriously damage the ecology.Traditional oil-water separation methods mainly rely on technologies such as different oil-water density or adsorption to achieve oil-water separation,but these has high energy consumption,low separation efficiency and poor separation performance,most of them can only separate slick and dispersed oil.The nanofibrous membranes prepared by electrospinning has the characteristics of small pore size,high porosity and large specific surface area,which can effectively separate emulsified oil.In this paper,electrospinning and amidoximation techniques are used to prepare polyacrylonitrile(PAN)-based nanofibrous nonwovens,the micro-nano roughness structure constructed on the surface to obtain oil-water separation membranes with special wettability.Investigated the separation flux and efficiency for different types of emulsified oils,analyzed the oil-water separation mechanism,which provides a new idea and practical basis for the development of electrospun oil-water separation membranes.The main work content is as follows:(1)Combining electrospun and electrospray technology to prepare PAN-based composite nanofiber membranes with selective wettability.With PAN nanofiber membrane as the framework,silica(SiO₂)particles were situ sprayed to constructed Cassie rough structure on the surface to fabricated SiO₂/PAN composite membrane.The surface microstructure of the membrane was adjusted by adjusting spinning parameters,such as PAN concentration,loading voltage,SiO₂concentration,etc.Investigated the influence of the amount of SiO₂spraying on the porosity and pore size,and it was found that the construction of a rough structure on the membrane surface can improve its wettability so that the materials exhibits hydrophilic/underwater oleophobic properties and has the potential to be used as an oil-water separation membrane.(2)Combining electrospun and amidoximation technology to prepare oil-water separation membrane with super wettability.On the basis of the SiO₂/PAN composite film,it is treated with amidoximation.Through the electrophilic addition reaction of the cyano group on the surface of PAN and hydroxylamine hydrochloride,the amidoxime group is introduced on the surface of the film to obtain AO-SiO₂/PAN nanofibrous membrane with high surface energy and micro-nano roughness structure.The effect of modification parameters on the conversion of cyano groups was studied.Use SEM and FE-SEM to analyze the surface microstructure,use FT-IR and XPS to detect the distribution of elements and groups on the membrane surface;use AFM and pore size distribution tester to measure the surface roughness.The study found that the pure PAN film surface was smooth,but after spraying SiO₂and amidoxime modification,the roughness was increased and the material appeared nano-size pores formed by particles and fibers.Through the wettability and oil-water separation performance tests,the material showed super hydrophilic/underwater superoleophobic properties and can efficiently separate emulsified oils with stable surface activity under the driving force of 20k Pa,which has the potential to be applied in the field of oil-water separation.(3)In order to realize the macro-quantity production of oil-water separation membranes and obtain oil-water separation membranes with high separation flux and efficiency,Directly amidoximation treatment to PAN polymer,which greatly increases the cyano conversion rate on the PAN surface.By doping graphene oxide(GO)in the spinning solution,an ultra-fine diameter GO/AO-PAN nanofibrous membrane is obtained.The physical and chemical properties of the membranes are studied,which shows that the addition of GO is beneficial to the wettability of the material;through the WCA,the membrane material has superhydrophilic/underwater superoleophobic properties,it shows excellent separation flux and efficiency for emulsified oils,and has repeated recycling.The oil-water separation field has certain application prospects.