Preparation And Properties Of Carbon Nanotubes/polyacrylonitrile/polyvinylidene Fluoride Membrane

Blending is a common method to improve membrane performance.By blending polyacrylonitrile and poly?vinylidene fluoride?,the hydrophilicity and mechanical properties of the membrane can be enhanced.The membrane performance can be further optimized by adding CNT.Therefore,the PAN/PVDF/CNT blend membrane was prepared,and the change of membrane performance with CNT contents was investigated.Firstly,the affecting factors such as the additive amount of the pore agent were determined.The pure water flux of the membrane is greatly influenced by polyvinylpyrrolidone?PVP?.When the proportion of PVP in the total mass reaches6%,the water flux is 832 L·m^-2·h^-1.Hydrophilicity decreases with the increase of PVDF,while the mechanical properties show the opposite trend.As the ratio of solute and solvent increases,the mechanical strength of the membrane increases.The water flux and hydrophilicity decrease with the increase of temperature in coagulation bath.The Contact Angle decreases with the increase of the solvent in the coagulation bath,and the hydrophilicity of the membrane is enhanced.Eventually the condition of membranes fabrication was determined as:the PVP proportion is 6%,the ratio of PAN and PVDF is 8:2,the ratio of solute and solvent is 18:82,the coagulation bath temperature is 25°C and the solvent ratio in the coagulation bath is 30%.Secondly,the effect of CNT on the properties of PAN membrane and PVDF membrane was investigated.Acidified CNT possesses the functional group of carboxyl group?-COOH?,which is beneficial to the uniform dispersion of CNT in the solvent,and improves the mixing degree of CNT and polymers.Acidified CNT enhances the mechanical properties of PAN membranes.The hydrophobicity of PVDF membranes is reduced by the acidified CNT.Finally,the effects of CNT content on the PAN/PVDF blend membranes were investigated.After the addition of acidified CNT,the finger-like pores of PAN/PVDF blend membrane are widened,and the hydrophobicity is enhanced.The maximum pure water flux is 398.1 L·m^-2·h^-1.The minimum value of FRR is 75%after 5filtration-cleaning cycles,indicating that the blend membrane has high cycle utilization and good anti-fouling performance.The?electron cloud of CNT is conjugated with F atoms and C?N bonds,which enhances the interaction between the polymers and improves the decomposition temperature of the blend membrane.When the CNT content is too high,due to the increase of surface roughness and the influence of stress concentration,the Contact Angle of the blend membranes becomes larger and the tensile strength decreases.The optimum CNT content is determined as 0.5%.