Effects of the addition of nano-sized SiO_2 on the structure and performance of PVDF/ SiO_2 ultrafiltration membrane

The unmodified,hydrophilic and hydrophobic nano-sized SiO2 were added into the PVDF casting solution respectively,and the PVDF/SiO2 hybrid membranes were prepared by phase inversion method.The effects of SiO2 concentration and the above-mentioned three types of SiO2 on the PVDF membrane performances such as pure water flux,rejection ratio,anti-fouling capability were examined.The experimental results indicated that membrane porosity,mean membrane pore size,pure water flux,rejection ration,anti-fouling capability increased with rising SiO2 concentration firstly and then decreased.Besides,when the SiO2 concentration was 2%,in terms of pure water flux,unmodified nano-sized SiO2 hybrid membrane was the best,followed by hydrophobic nano-sized SiO2 hybrid membrane and hydrophilic nano-sized SiO2 hybrid membrane.Inversely,in terms of anti-fouling capability,hydrophilic nano-sized SiO2 hybrid membrane was the optimal,followed by unmodified nano-sized SiO2 hybrid membrane and hydrophobic nano-sized SiO2 hybrid membrane.