Interfacial Treatment And Performance Study Of Fiber Tube Reinforced Polyvinylidene Fluoride Hollow Fiber Membrane

With the development of social economy and the growth of population,the shortage of water resources and water pollution have become important factors of restricting the development of our economy and society.Therefore,in order to face the contradiction between the quality of the water resources and the economic development,we urgently need a water treatment technology which is suitable for the development of the times.The strength of traditional pure PVDF hollow fiber membrane application in membrane bioreactor is low,in the face of harsh water environment,it is difficult to meet the requirements,the fiber tube reinforced PVDF hollow fiber membrane can greatly enhance the membrane strength,but because of the limited binding force between the fiber tube and the membrane casting solution,the interface layer of reinforced membrane produces the peeling phenomenon by the impact of water flow and the oscillation in the process of using,greatly affected the fiber tube reinforced hollow fiber membrane life,Therefore,it is very important to find methods to enhance the interfacial bonding ability of the reinforced membrane without affecting the performance of the reinforced membrane.First of all,As the membrane reinforcement,the braided tube and knitted tube were modified by two methods:1,the outer surface of the two kinds of fiber tube were coated by KH570 coupling agent and acrylic adhesive;2,the outer surface of the two kinds of fiber tube were treated by the different time of low temperature plasma etching in oxygen atmosphere,a small amount of hydrophilic groups was grafted on the outer surface of fiber tubes.Hydrophilicity of the outer surface of the tubes was thus increased,the effects of different factors on fiber tubes such as conveying speed,modifiers of different dosage,treatment time of low temperature plasma on the properties of reinforced PVDF hollow fiber membrane such as water flux,porosity and average pore size,tensile strength,burst strength were studied.The water flux,the average pore diameter and the porosity of the fiber reinforced membrane were influenced greatly by different fiber pipe conveying speed,and the impact of tensile strength to the fiber tubes was small.The effect of the dosage of modifier on the properties of fiber reinforced membrane was different,and the dosage of modifier can't meet the requirement of the membrane using too much or too little.Low temperature plasma treatment time of fiber tube was the main effect of the membrane interface binding force.Secondly,the fiber tubes of different conveying speed,plasma treatment time and dosage of modifier were treated by ultrasonic under the same conditions,fiber reinforced PVDF hollow fiber membrane water flux were tested before and after ultrasound in order to simulate the using effect.The optimal technology was therefore concluded.The optimal process for the preparation is obtained:the optimal dosage of KH570 coupling agent and acrylate adhesive is 3 g/5m,the optimal etching time of low temperature plasma on braided tube is 10 min,the optimal etching time of low temperature plasma on knitted tube is 15 min,and the optimal conveying speed of the fiber tube reinforced membrane with modifier and the braided tube reinforced membrane without modifier is 15 m/min,the best knitted tube reinforced membrane without modifier conveying speed is 20 m/min.The modification effect of acrylic adhesive on braided tube is better,and the effect of KH570 coupling agent on knitted tube reinforced membrane is better.