弱可见光催化活性La-TiO2-还原氧化石墨烯填充聚偏氟乙烯共混膜的构建

为提高聚偏氟乙烯(PVDF)超滤膜的通量及抗污染性能，首先利用吸附相反应技术耦合乙醇热处理制备La掺杂TiO₂-还原氧化石墨烯(La-TiO₂-RGO)，再将其与PVDF共混制备La-TiO₂-RGO/PVDF抗污染超滤膜。结果表明，均匀分散于PVDF高分子中表面亲水的La-TiO₂-RGO增多，La-TiO₂-RGO/PVDF共混膜的水通量和抗污染性能也显著提升。当La-TiO₂-RGO/PVDF共混膜中出现团聚体，则会削弱其膜通量和抗污染性。在La-TiO₂-RGO填充量(与PVDF质量比)为2.0%时，La-TiO₂-RGO/PVDF共混膜具有最优纯水通量。La-TiO₂-RGO/PVDF共混膜最高纯水通量可达171.5 L·m?2·h?1，是PVDF膜的5倍以上，其通量衰减速率也明显低于PVDF膜。另外，由于La-TiO₂-RGO具有可见光催化活性，被污染后的La-TiO₂-RGO/PVDF共混膜经过光照处理后用水清洗，其膜通量恢复率较直接用水清洗后的通量恢复率大幅提高；热处理温度升高，La-TiO₂-RGO弱可见光活性增强，光照后La-TiO₂-RGO/PVDF共混膜通量恢复率变大。但过高热处理温度抑制了La-TiO₂-RGO中Ti3+形成，且削弱其光活性，La-TiO₂-RGO/PVDF共混膜通量恢复率反而下降；对于La-TiO₂-RGO填充量为2.0%的La-TiO₂-RGO/PVDF共混膜，被污染后分别采用直接水清洗、仅光照处理2 h、先光照处理2 h后水清洗的膜通量恢复率分别为79.28%、52.42%、90.01%。 

Fabrication of polyvinylidene fluoride blending membranes filled by La-TiO2-reduced graphene oxide with photocatalytic activity

To improve the flux and antifouling performance of polyvinylidene fluoride (PVDF) ultrafiltration membrane, La doped TiO₂-reduced graphene (La-TiO₂-RGO) was first synthesized by the adsorption phase reaction coupled with alcohol solvothermal reduction processes. Followed that, La-TiO₂-RGO was blended with PVDF to fabricate a La-TiO₂-RGO/PVDF ultrafiltration membrane with high anti-fouling performance. The results show that the water flux and antifouling performance of the La-TiO₂-RGO/PVDF blending membrane increase, when more well-distributed La-TiO₂-RGO with hydrophilic groups added. The aggregations generate in the La-TiO₂-RGO/PVDF blending membranes will depress their water flux and antifouling performance. When the loading content (mass ratio to PVDF) of La-TiO₂-RGO is 2.0%, the La-TiO₂-RGO/PVDF blending membrane has the best pure water flux. The optimum pure water flux of the La-TiO₂-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-TiO₂-RGO/PVDF blending membrane is significantly lower than that of the PVDF membrane. The flux recovery of the contaminated La-TiO₂-RGO/PVDF blending membrane treated by illumination then washing is obviously higher than that just treated by washing, due to the addition of La-TiO₂-RGO with photocatalytic activity. The increase in the solvothermal temperature enhances the photocatalytic activity of La-TiO₂-RGO, thus improving the flux recovery rate of the La-TiO₂-RGO/PVDF membranes after light irradiation. However, too high solvothermal temperature inhibites the formation of Ti3+ in La-TiO₂-RGO, which weakens its photoactivity and decreases the flux recovery rate of the resulting La-TiO₂-RGO/PVDF blending membranes. For the La-TiO₂-RGO/PVDF blending membrane filled with La-TiO₂-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.