Abstract:
To improve the flux and antifouling performance of polyvinylidene fluoride (PVDF) ultrafiltration membrane, La doped TiO
2-reduced graphene (La-TiO
2-RGO) was first synthesized by the adsorption phase reaction coupled with alcohol solvothermal reduction processes. Followed that, La-TiO
2-RGO was blended with PVDF to fabricate a La-TiO
2-RGO/PVDF ultrafiltration membrane with high anti-fouling performance. The results show that the water flux and antifouling performance of the La-TiO
2-RGO/PVDF blending membrane increase, when more well-distributed La-TiO
2-RGO with hydrophilic groups added. The aggregations generate in the La-TiO
2-RGO/PVDF blending membranes will depress their water flux and antifouling performance. When the loading content (mass ratio to PVDF) of La-TiO
2-RGO is 2.0%, the La-TiO
2-RGO/PVDF blending membrane has the best pure water flux. The optimum pure water flux of the La-TiO
2-RGO/PVDF blending membrane reaches 171.5 L·m
−2·h
−1, which is 5 times as high as that of the PVDF membrane. And the flux decay rate of the La-TiO
2-RGO/PVDF blending membrane is significantly lower than that of the PVDF membrane. The flux recovery of the contaminated La-TiO
2-RGO/PVDF blending membrane treated by illumination then washing is obviously higher than that just treated by washing, due to the addition of La-TiO
2-RGO with photocatalytic activity. The increase in the solvothermal temperature enhances the photocatalytic activity of La-TiO
2-RGO, thus improving the flux recovery rate of the La-TiO
2-RGO/PVDF membranes after light irradiation. However, too high solvothermal temperature inhibites the formation of Ti
3+ in La-TiO
2-RGO, which weakens its photoactivity and decreases the flux recovery rate of the resulting La-TiO
2-RGO/PVDF blending membranes. For the La-TiO
2-RGO/PVDF blending membrane filled with La-TiO
2-RGO loading of 2.0%, the flux recovery rates of contaminated membrane are 79.28%, 52.42% and 90.01%, respectively, after washing, illumination for 2 h and illumination for 2 h then washing.