Membrane Distillation Was Developed Using A Fluoroalkylated Porous Carbon Microsphere/polyvinylidene Fluoride Mixed Matrix Membrane

Membrane distillation,a membrane separation based on hydrophobic microporous membrane,has attracted wide attention in water treatment field in recent years.The fabrication of hydrophobic membranes with high flux is the key to enhance the performance of membrane distillation.Activated carbon(AC),as an inorganic material with excellence performance,has broad application prospects.The AC particles could improve membrane separation performance greatly when AC particles dispersed well in polymer casting solution and had good compatibility with membrane material.Here,we prepared high flux PVDF/AC hybrid membrane.Three parts are included as following:In order to enhance the dispersion and compatibility of AC particles in PVDF matrix,the AC was functionalized by fluoroalkyl groups via the reaction between carboxylic activated carbons and octafluoropentanol(OFP).Results showed that the AC-OFP could be well dispersed in polymer casting solution.High-flux hydrophobic membrane was prepared by simply blending PVDF and functionalized AC-OFP particles via a conventional phase inversion method.The PVDF/AC-OFP membrane exhibited satisfying hydrophobic compared with the membrane with pristine AC particles.In comparison with PVDF/AC membrane,PVDF/AC-OFP membrane was able to improve the DCMD flux up to 38.9%(from 29.8 kg/m2 h up to 41.4 kg/m2·h),which was achieved by optimizing the AC-OFP particles addition of to 0.15 wt.%.Based on the above work,other three fluoroalkyl agents(Tetrafluoro-1-propanol(TFP),Dodecafluoro-l-heptanol(DFP)and Hexadecafluoro-l-nonanol(HFN)were chosen to achieve chemical grafting.And the effect of fluoroalkyl chain on the stability of casting solution,the dispersion of AC particles in membrane matrix and membranes separation performance were investigated.Result showed that all four AC-fluoroalkyl particles could had a better dispersion in membrane matrix than pristine AC and the AC-HFN with longest chain had the largest role in improving the hydrophobic and adding pore size.The DCMD result showed that all the four PVDF/AC-fluoroalkyl membranes had higher flux rather than the PVDF/AC membrane and the PVDF/AC-HFN membrane(44.7kg/m2·h)is the highest one.