Preparation And Oil-water Separation Performance Of Surfactant/PSMA Grafted Carbon Nanotube Composite Membrane

With the environmental protection gradually gaining popularity,the oil pollution in water has also aroused people's high concern.Oil pollution caused by industrial production,domestic discharge and oil leakage is a common form of water pollution.How to efficiently and quickly deal with oil-containing wastewater is of great significance for the restoration and utilization of water resources and environmental protection.Some traditional methods of oil and water separation have high energy consumption and low separation efficiency.Some require the use of chemical reagents to cause secondary pollution;Some have long processing cycles.In recent years,the emerging membrane separation technology has attracted much attention due to its advantages of fast,high efficiency and low energy consumption.Therefore,it is of great theoretical and practical significance to develop separation membrane with anti-fouling performance and improve the reuse rate of separation membrane.In this paper,styrene-maleic anhydride copolymer(PSMA)was grafted onto MWCNT surface by in situ free radical polymerization,and then compounded with fluorocarbon surfactant(FS-51)by supramolecular force.A series of oil-water separation membranes were prepared by dip-coating and electrostatic spinning with steel wire mesh as supporting substrate.The specific work is as follows:The synthesis conditions of styrene-maleic anhydride were optimized: styrene-maleic anhydride copolymer(PSMA)was synthesized by using different molar ratio of monomer,ethyl acetate and toluene as solvents,and the content of maleic anhydride in copolymer was determined by acid-base titration.The structure of PSMA was characterized by Fourier transform infrared spectroscopy(FTIR)and nuclear magnetic resonance spectroscopy(1HNMR?13C-NMR).The PSMA/MWCNT complex was prepared by grafting PSMA onto acidified multiwalled carbon nanotubes(a-MWCNT)by in situ radical polymerization.The structure,apparent morphology and heat resistance of PSMA/MWCNT were characterized by FTIR,laser Raman spectroscopy,TEM and TGA.The results showed that PSMA was successfully coated on the surface of MWCNT with a thickness of about 12~15nm.PSMA/FS and PSMA/MWCNT/FS composites were obtained by combining PSMA,PSMA/MWCNT and fluorocarbon surfactant(FS-51)by supramolecular force.Three kinds of stainless steel mesh with different pore sizes were selected as the supporting substrate,and the PSMA,PSMA/FS and PSMA/MWCNT/FS were respectively coated on the stainless steel wire mesh by the dip coating method.The contact angle,oilwater separation efficiency,anti-fouling and reuse rate of the membrane have been studied.The results show that the oil-water separation efficiency can be improved by decreasing the aperture of steel mesh and adding FS and MWCNT.The PSMA membrane can not separate oil/water mixture.When the membrane prepared by PSMA/FS and PSMA/MWCNT/FS are used for the separation of oil/water mixture,the water can quickly pass through the membrane,and the oil remains above the meshes,resulting in the effiective oil-water separating;For membranes with the same composition,the oil-water separation efficiency increases with the decreasing of the steel mesh aperture.With the same steel mesh aperture,the membrane containing MWCNT has higher oil-water separation efficiency and reuse rate.PSMA/FS and PSMA/MWCNT/FS membranes have good antifouling properties.The oilwater separation efficiency of 300 mesh steel mesh coated with PSMA/MWCNT/FS membrane reached 99%.After repeated 20 oil-water separation experiments,the oil-water separation efficiency decreased slightly to 97%.Using DMF as solvent,the spinning solutions with a certain concentration were prepared by PSMA,PSMA/MWCNT,PSMA/FS and PSMA/MWCNT/FS respectively,and the non woven membranes were obtained by electrostatic spinning with 200 mesh stainless steel mesh as supporting substrate.And FS-51 aqueous solution was spraed on PSMA and PSMA/MWCNT membranes.The influence of spinning solution concentration on nanofiber morphology was investigated,and the microstructure,contact angle,oil-water separation efficiency and reuse rate of spinning membrane were characterized.After spraying the FS-51,the surfaces of the PSMA/MWCNT and PSMA membranes show a trabsition from superhydrophobicity(water contact angle > 119 °,oil contact Angle = 0 °)to superhydrophilicty(water contact angle = 0 °,oil contact angle > 120 °).The results of oilwater separation efficiency show that the oil-water separation efficiency of the membrane with MWCNT are higher than that of the membrane without MWCNT when other conditions are the same.When the concentration of spinning solution is greater than 0.45g/ml,the influence of MWCNT is no longer obvious,whether by PSMA or PSMA/MWCNT first spinning and then spraying FS membrane,or by PSMA/MWCNT/FS composite directly spinning membrane,oil-water separation efficiency can reach 100%.The addition of MWCNT improves the oil-water separation efficiency and the reuse rate of the composite membranes.In the spinning membrane containing MWCNT prepared at a high concentration of spinning solution(0.45,0.50g/ml),no matter how fluorocarbon surfactant is added,the oil-water separation efficiency of the spinning membrane can reach 100%.After 20 separation sysles of oil-water separation,the oil-water separation efficiency can still reach 99%.