以无机纳米粒子(SiO2)与PVDF共混,使用相转化法制得无机-有机平板超滤膜.考察了SiO2含量在1%~3%(质量分数)范围内对PVDF超滤膜的接触角、膜平均孔径及渗透性能的影响.以BSA为标准污染物,通过过滤实验评价了SiO2改性后的PVDF超滤膜的抗污染行为.通过探针修饰,以原子力显微镜(AFM)检测技术定量分析了膜污染过程中膜面与污染物相互间的微观作用力.结果表明,添加SiO2能有效改善PVDF超滤膜的亲水性能,影响膜平均孔径和渗透性能.SiO2质量分数为1%的改性超滤膜(P1膜)孔径最大,接触角最小且渗透性能最佳,膜表面和断面微观结构的SEM表征结果也进一步证实了上述结论.膜污染评价结果显示,在BSA过滤过程中,P1膜通量衰减速度慢、清洗恢复率高,抗污染性能较好.AFM数据显示,膜面与BSA间的粘附力随膜的亲水性增大而下降,并随着污染物在膜表面的累积程度逐渐下降.初步说明膜与BSA间的微观作用力是导致膜污染发生的主要原因,SiO2的添加能够有效降低膜的初期污染进而提高膜抗污染性能.
Organic-inorganic plate ultrafiltration membranes were prepared via phase inversion method through blending SiO2 nanoparticles with PVDF.The effects of SiO2 concentration from 1%to 3% on the contact angle,average pore size and permeability of membranes were investigated.The anti-fouling behavior of PVDF/SiO2 membranes was evaluated by macro filtration experiment with BSA as standard foulant.In addition,the micro-forces of membrane-BSA foulant in the fouling process were investigated by atomic force microscope(AFM)in conjunction with self-made foulant-coated colloidal probe.The results revealed that the flux,average pore size and hydrophilicity of the membranes were improved effectively by the additive of SiO2.The performance was optimum when the adding amount of SiO2 was 1%(mass fractopm).The above-mentioned conclusions were confirmed by the SEM images of surface and cross-section microstructure.The results of membrane fouling evaluation showed that,for P1 membrane,the flux decline rate was decreased slowly,and the flux recovery rate was improved.Meanwhile,anti-fouling performance was better.The AFM data indicated that the adhesive forces of membranes-BSA foulant were decreased with the imcreasing of modified membranes hydrophilicity,and the gradual droping of BSA foulant accumulated in the surface of membranes.It illustrated preliminarily that the interactions of membranes and BSA foulant was the main reason of membrane fouling.That is,the membrane fouling in the initial filtration stage was reduced by the additive of SiO2,which lead to improve the anti-fouling properties of PVDF ultrafiltration membranes.