纳米蒙脱土改性聚乳酸超滤膜的制备与性能研究

Studies on preparation and performance of poly(lactic acid)ultrafiltration membrane modified by montmorillonite nanoparticles

采用相转化法制备了纳米蒙脱土改性的聚乳酸超滤膜,讨论了纳米蒙脱土对聚乳酸膜结构和性能的影响。通过孔隙率及平均孔径尺寸测定、接触角测量、扫描电子显微镜、原子力显微镜、热重分析等实验分别对膜的微观结构、亲水性以及热稳定性进行了表征。通过纯水通量、蛋白截留率、水通量恢复率以及通量衰减等实验分别对膜的过滤性能以及抗污染性能进行了研究。结果表明,纳米蒙脱土的加入使复合膜表面的亲水性得到明显改善,孔隙率与平均孔径尺寸明显增大。当膜中纳米蒙脱土的质量分数为0.2%时,复合膜的表面比纯膜更加光滑,断面的指状孔尺寸增大,热稳定性提高,纯水通量达到最大值450L/(m^2·h),约是纯膜的4.7倍,水通量恢复率达到95.1%,抗污染性能最佳。过量的纳米蒙脱土会使铸膜液的粘度明显增加,并造成纳米粒子的团聚,从而导致膜的各方面性能均下降。

Poly(lactic acid)(PLA)ultrafiltration membranes modified by montmorillonite(MMT)nanoparticles were fabricated via phase inversion method.The influences of MMT nanoparticles on the structure and performances of the membranes were investigated by water contact angle measurement,porosity and mean pore size measurement,scanning electron microscopy(SEM)analysis,atomic force microscopy(AFM)analysis,thermogravimetric analysis(TGA),filtration and fouling experiments.The results revealed that the hydrophilicity of the composite membrane surface was improved significantly,and the porosity and mean pore size increased after MMT nanoparticles were added.When the mass fraction of MMT nanoparticle was0.2%,the surface of the composite membrane surface was smoother than that of pure membrane,the size of finger-like cavities increased,the thermal stability increased,the pure water flux reached the maximum value with450L/(m2·h),the flux recovery ratio reached up to95.1%and the antifouling property was the best.While excessive dosage of MMT nanoparticles will significantly increase the viscosity of casting solution,and make the aggregation of nanoparticles,resulting in the poor performance of the PLA membrane.