PVDF-SiO_2中空纤维复合膜的制备和表征

采用相转化法制备聚偏氟乙烯(PVDF)-二氧化硅(SiO2)中空纤维复合膜,讨论了纳米SiO2粒子对PVDF膜结构和性能的影响。通过扫描电子显微镜、能谱、傅里叶红外光谱、热分析、材料试验、接触角测量和超滤实验分别对不同膜的微观结构、化学组成、热稳定性、机械强度、亲水性以及分离性能、抗污染能力进行了联合表征。结果表明:添加SiO2粒子有利于PVDF由α相向β相转变,复合膜的性能与纯PVDF膜相比有明显改善。当w(SiO2)=3%时,纳米颗粒分散较均匀,膜断裂强度为纯PVDF膜的2.7倍,纯水通量由81.6 L/(h.m2)提高到160.0 L/(h.m2),热稳定性、亲水性和抗污染性显著提高;但过高的SiO2含量(w3%)会引起纳米颗粒团聚而导致膜的各项指标下降。

Preparation and Characterization of PVDF-SiO_2 Composite Hollow Fiber Membrane

Poly(vinylidene fluoride) (PVDF)-silica(SiO_2) composite hollow fiber membranes were prepared by phase transition process.The microstructure, chemical composition, thermal stability, mechanical strength, hydrophilicity, separation performance and antifouling ability of the membranes were characterized by scanning electron microscopy (SEM), energy dispersion of X-ray (EDX), Fourier infrared spectrometer (FT-IR), thermogravimetric analysis (TGA), mechanical property test, contact angle measurement and ultrafiltration (UF) experiment.The results showed that crystal structure of PVDF underwent a transition from α-phase to β-phase clue to the addition of SiO_2.Compared to those of the pure PVDF membrane, the performances of composite membranes improved greatly.When the mass fraction of SiO_2 was 3%, particles uniformly dispersed and the break strength of the composite membrane was 2.7 times higher than that of the pure PVDF membrane. Pure water flux increased from 81.6 L/(h·m~2) of the PVDF membrane to 160.0 L/(h·m~2). Moreover, the thermal stability, hydrophilicity and antifouling properties were enhanced significantly.However, excess amount of SiO_2 (w > 3%) led to particle aggregation and the decline of the performance of the composite hollow fiber membranes.