Hydrophilic Modification Of PTFE Flat Sheet Membrane Via Self-polymerization Of Catechol

Among wastewater purification technology techniques,membrane separation has attracted much attention for its simple and cost-effective process.PTFE flat membrane is a membrane material with suitable pore size,high porosity,high mechanical strength and good chemical stability and is a promising candidate for harsh water treatment.However,the strong hydrophobicity of PTFE flat membrane causes a serious membrane fouling and limits the application of this membrane in wastewater purification.To improve the fouling resistance of membrane,hydrophilic modification of PTFE flat membrane is necessary.This paper focuses on fabricating hydrophilic coatings on PTFE flat membrane via one-step co-deposition method and second modification method on the basis of self-polymerization reaction of catechol?CA?.Then,the surface functional groups,the surface chemical composition and the surface morphology of the PTFE flat membrane were investigated by attenuated total reflectance fourier transform infrared?ATR-FTIR?,x-ray photoelectron spectroscopy?XPS?,field emission scanning electron microscopy?FESEM?.Finally,the effects of monomer concentration and reaction time on the modified PTFE flat membrane are studied.The main research contents are as follows:?1?To improve hydrophilicity and anti-fouling property of the polytetrafluoroethylene?PTFE?flat microfiltration?MF?membrane,a facile method was developed to modify the membrane via the co-deposition of CA and polyethyleneimine?PEI?followed by surface mineralization of ?-?2,3-epoxypropoxy?propytrimethoxysilane?KH560?.The experimental results show that the modified PTFE membrane surface still maintain fiber network structure,the fibers and the nodes are attached with a large amount of solid particles,the surface roughness increases,the pore size and porosity decreased;Hydrophilic groups such as-OH and-NH2 appeared on the surface of the modified PTFE membrane;With the increase of KH560 concentration,the contact angle of the modified PTFE flat membrane decreased,the water flux increased first and then decreased;The optimal experimental conditions are as follows: the concentration of CA is 1.2 g/L,the mass ratio of CA/PEI is 4:1,the reaction time is 8h,the concentration of KH560 is 2%.The contact angle of the modified PTFE membrane reduced from 137° to 18°,and the water flux reached 9750 L·m^-2·h^-1.Then,the oil/water separation tests were conducted using the modified PTFE flat membranes.The as-prepared hydrophilic PTFE flat membranes possess an excellent oil resistant ability with oil rejection ratio about 99%.Finally,the surface stability of the modified membrane was studied and the mineralized membrane showed excellent acid resistant ability.?2?In this paper,a facile method was developed to modify the PTFE flat MF membrane via the co-deposition of CA and silane coupling agent for the improvement of hydrophilicity and anti-fouling property.The experimental results show that the CA/?-?2,3-epoxypropoxy?propytrimethoxysilane?KH560?or CA/3-mercaptopropyl trimethoxysilane?KH590?modified PTFE membrane still maintain fiber network structure,the hydrophilic coatings are attached to the fibers and the nodes uniformly;The hydrophilic-OH is appeared on both of the modified PTFE membrane;With the increase of KH560 or KH590 concentration,the contact angle of two kinds of the modified PTFE membranes decreased,the water flux increased first and then decreased;With the increase of reaction time,the contact angle of two kinds of the modified PTFE membranes decreased,the water flux increased first and then decreased.The optimal experimental conditions are as follows: the concentration of KH560 and KH590 are 2 g/L and 1.6 g/L,respectively,the reaction time is 6h.The contact angle of the CA/KH560 and CA/KH590 modified PTFE flat membranes decreased from 145° to 16° and 37°,respectively.The corresponding water flux is 10215 L·m^-2·h^-1 and 8490 L·m^-2·h^-1,respectively.Then,the anti-fouling tests were conducted using the modified PTFE flat membranes.The as-prepared hydrophilic PTFE flat membranes possess excellent bovine serumalbumin?BSA?fouling resistance.Finally,the surface stability of the modified membrane was studied and the modified membranes show excellent stability under the acidic condition but weak to strong alkali.