The Preparation Of Super-hydrophilic And Anti-pollution AOPAN/RC Composite Membrane And Its Application In Treatment Of Oily Wastewater

Industrial production and daily life have brought serious oil pollution problems.It is of great significance to develop an oil-water separation material with simple operation,good effect and long service life.Filter-type oil-water separation membrane materials are widely used because of their convenient preparation and the ability to scale up and operate at room temperature.Electrospinning nanofiber membranes have interconnected pores,larger porosity and adjustable surface structure,so they are widely used in the separation of oil-water mixtures and their emulsions.Compared with traditional membrane separation materials,the permeation flux of electrospun membranes is an order of magnitude higher,but there are also problems such as poor pollution resistance and weak durability during recycling.In this study,the original polyacrylonitrile/cellulose acetate membrane material was chemically modified through deacetylation and ammoximation reactions to prepare a super-wetting and anti-pollution electrospun nanofiber composite membrane,then it was applied to the separation process of oil-in-water emulsion with droplet size<20μm.The results show that the modified electrospun membrane can effectively separate emulsions with smaller particle diameters,and exhibits super anti-pollution performance during recycling.The main research content covers the following three points:（1）Select cellulose acetate（CA）and polyacrylonitrile（PAN）with excellent spinnability and easy hydrophilic modification as raw materials for electrospinning,and prepare uniform and stable PAN/CA composite membranes by cross-spinning.The mass ratio of PAN and CA in the composite film was measured,and the surface structure was observed by scanning electron microscope（SEM）,the mechanical properties were tested by the universal material testing machine,the water contact angle（WCA）and wetting performance of the film in the air were tested by a contact angle meter.The results show that when the mass ratio of PAN/CA is 20/80,the pure water permeation flux of the composite membrane is as high as 7413 L/（m²h）,the tensile strength is 1.38 MPa,and the elongation at break is 10.84%.In the air,water droplets can infiltrate the surface of the membrane in only 2 min 53 s,showing good wettability.（2）The PAN/CA composite membrane was immersed in Na OH solution and HONH₂HCl solution respectively to obtain a superhydrophilic anti-pollution ammoximated polyacrylonitrile/regenerated cellulose（AOPAN/RC）composite membrane.The structure change,functional group change,wettability transition and the change of underwater oil contact angle of the membrane before and after modification were observed.The separation performance of the membrane to emulsion was tested,and the anti-pollution performance of the membrane in the recycling process was investigated.And the adhesion performance to various oils.The results showed that after modification,a large number of hydrophilic functional groups were added to the surface of the composite membrane,and the membrane changed from hydrophobic to superhydrophilic.The permeation flux of pure water was as high as 6085 L/（m²h）,and the permeation flux of emulsion reached 3485L/（m²h）,the highest oil-water separation efficiency is 99.59%,and the oil content in the filtrate is as low as 5.3ppm.In addition,the membrane exhibits a stable separation effect and excellent anti-pollution performance during the ten-cycle separation process.At the same time,it also exhibits ultra-low adhesion to high-viscosity castor oil.（3）The effect of the AOPAN/RC composite membrane on the actual wastewater treatment was explored,and the customized continuous filtration backwash device was used to explore the application of the membrane in the large-scale continuous oil-water separation process.Focus on testing the recycling performance of the composite membrane and its performance change after recycling.The results show that the separation efficiency of the membrane for actual wastewater is 80.42%and it remains stable during the five-cycle separation process.After use,the underwater oil contact angle of the membrane can still reach 138.7°±0.68°;in the oil-water separation test of the expanded device,the membrane also shows a separation efficiency of up to 99.93%,with a maximum permeation flux of 3576 L/（m²h）.