Effect of SiO_2 nanoparticles on polyvinylidene fluoride (PVDF) ultrafiltration membrane

Inorganic nanoparticles—SiO_2 can be added into the polyvinylidene fluoride casting solution,and nanoinorganic-organic composite membrane is made.The composite membrane has some improvements in characteristics compared with pure PVDF membrane.If appropriate SiO_2 nanoparticles are added,the pure water flux of membrane is improved but the retention does not decrease.As it can be seen that the addition of SiO_2 nanoparticles causes a strong increase of the viscosity,so it makes easier casting operation.At the same time SiO_2 nanoparticles have some influence on the membrane formation.It can be seen from the phase diagram that SiO_2 nanoparticles shift the binodal's position.So the water tolerance decreaced.From the DSC curves,the results show that in the composite membrane the crystal degree of PVDF has increased.So SiO_2 nanoparticles delay the membrane formation process.