添加剂共混改性CA正渗透膜的制备及抗污染性研究

发布时间：2018-03-11 06:36

本文选题：正渗透膜　切入点：纳米颗粒　出处：《西安建筑科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：缺乏高性能的渗透膜是阻碍正渗透技术发展的主要因素。研究证明,亲水性添加剂共混能够有效提高CA正渗透膜性能。目前,有关添加剂改性CA膜方面的研究缺少系统性和全面性。本文从多方面系统地研究了6种添加剂对CA正渗透膜性能的影响。主要研究内容包括:以醋酸纤维素(CA)为膜材料,分别以ZnCl2、乳酸、聚乙烯吡咯烷酮(PVP)、SiO2、TiO2和功能化的碳纳米管(fCNT)为添加剂,利用相转化法对CA正渗透膜进行共混改性;并利用原子力显微镜(AFM)、接触角测定仪和扫描电子显微镜(SEM)考察了添加剂对CA膜结构和表面特性的影响;以及通过测定不同CA膜的水通量及反向盐通量,研究了添加剂对CA正渗透膜分离性能的影响;同时,测定了CA膜在牛血清蛋白(BSA)污染实验中的通量衰减速率和通量恢复率,并结合不同CA正渗透膜表面与污染物BSA之间的微观作用力,研究了添加剂对CA膜的抗BSA污染性能的影响。结果表明:(1)乳酸和ZnCl2对CA膜粗糙度无明显影响;PVP使得CA膜的粗糙度增加了3nm,但不受其含量影响;当纳米颗粒添加剂fCNT、TiO2和SiO2的含量分别增加到1wt%,2wt%和2wt%时,CA膜中的纳米颗粒出现团聚作用,使得CA膜粗糙度急剧增大。6种添加剂均能提高CA膜的表面亲水性,而且亲水性随添加剂含量的增加而增强,其效果从好到差依次是:fCNT、ZnCl2、TiO2、SiO2、乳酸、PVP。(2)6种添加剂均可优化CA膜内部结构,使得CA内部膜孔增大,指状孔数量增多。其中,传统添加剂ZnCl2的效果最佳;CA膜ZnCl2-2的内部膜孔直径最大,弯曲率最小。与ZnCl2相比,其它5种添加剂改性的CA膜的指状孔数量较少。(3)在提高CA膜的水通量方面,ZnCl2效果最佳,CA膜ZnCl2-2水通量高达15.7 L/(m2?h),比无添加剂CA膜和商业CTA膜分别高175%和34%。乳酸和PVP改性的CA膜水通量分别是14.6和10.8 L/(m2?h)。3种纳米颗粒添加剂对CA膜的水通量有提高,但效果不如ZnCl2和乳酸,其通量约为9 L/(m2?h)。6种添加剂均可降低CA正渗透膜的反向盐通量,其中ZnCl2和3种纳米颗粒添加剂的效果最佳,最低可达0.458 g/(m2?h),其次是PVP,最差的是乳酸。(4)3种纳米颗粒对CA膜通量衰减速率降低效果相近且最佳,其次是ZnCl2,最后是PVP和乳酸。纳米颗粒改性的CA膜的通量恢复率均在96%以上,其次是CA膜ZnCl2-2通量恢复率为96.5%,乳酸-5和PVP-2分别为89.3%、85.5%。BSA与CA膜之间的微观作用力由弱到强依次是:含纳米颗粒CA膜、ZnCl2-2、乳酸-5、PVP-2和无添加剂CA膜。总之,纳米颗粒fCNT、TiO2和SiO2对CA膜的抗BSA污染性提高效果优于传统添加剂ZnCl2、乳酸、PVP。
[Abstract]:The lack of high performance permeable membrane is the main factor that hinders the development of forward osmotic technology. The study shows that hydrophilic additive blend can effectively improve the performance of CA forward permeable membrane. The effect of six additives on the performance of CA membrane was systematically studied in this paper. The main research contents include: cellulose acetate (CA) was used as membrane material, and Cellulose Acetate (CA) was used as membrane material. With ZnCl _ 2, lactic acid, PVP _ (2) O _ (2) O _ (2) TIO _ (2) and functionalized carbon nanotubes (fCNT) as additives, CA + permeable membrane was modified by phase inversion method. The effects of additives on the structure and surface properties of CA membrane were investigated by AFM, contact angle analyzer and scanning electron microscope (SEM), and the water flux and reverse salt flux of different CA membranes were measured. The effect of additives on the separation performance of CA positive osmotic membrane was studied, and the flux attenuation rate and flux recovery rate of CA membrane in bovine serum protein (BSA) contaminated experiment were determined. Combined with the microcosmic interaction between the surface of different CA positive permeable membrane and contaminant BSA, The effect of additives on the anti-fouling performance of CA membrane was studied. The results showed that the roughness of CA membrane was increased by 3nm but not affected by the content of ZnCl2 and lactic acid. When the content of FCNT _ 2 TIO _ 2 and SiO2 increased to 1 w _ t% and 2 wt%, respectively, the nano-particles in CA film were agglomerated, and the surface hydrophilicity of CA membrane was improved by increasing the roughness of CA membrane rapidly. 6 kinds of additives could improve the surface hydrophilicity of CA film, and the surface hydrophilicity of CA film could be improved by the addition of FCNT _ 2 and SiO2, respectively. Moreover, the hydrophilicity increases with the increase of additive content, and the effect is in the order of: fCNT / ZnCl _ 2 / TIO _ 2 / Sio _ 2. The internal structure of CA membrane can be optimized by six kinds of additives, and the internal pore size of CA increases and the number of finger-like pores increases. The effect of traditional additive ZnCl2 is the best. The diameter of inner membrane of CA membrane ZnCl2-2 is the largest, and the bending rate is the smallest. Compared with ZnCl2, The other 5 kinds of additives modified CA membrane have fewer finger pores. 3) the best effect of ZnCl _ 2 is to increase the water flux of CA membrane. The ZnCl2-2 water flux of CA membrane is up to 15.7L / m ~ (2) 路m ~ (2) ~ (-1) 路L ~ (-1) 路L ~ (-1) ~ (-1)? The water flux of CA membrane modified by lactic acid and PVP was 14. 6 and 10. 8 L / m ~ (2), respectively. The water flux of CA membrane was increased by Hb.3 nano-particle additive, but the effect was not as good as that of ZnCl2 and lactic acid, and the flux was about 9 L / m ~ (2)? The reverse salt flux of CA positive osmotic membrane can be reduced by Hb.6 additives. ZnCl2 and three kinds of nano-particle additives have the best effect, and the lowest is 0.458 g / m ~ (2)? The flux decay rate of CA membrane was similar and the best, followed by ZnCl _ 2, PVP and lactic acid. The flux recovery rate of CA membrane modified by nano-particles was above 96%, respectively. Secondly, the recovery rate of ZnCl2-2 flux of CA membrane was 96. 5, and that of lactate-5 and PVP-2 were 89. 3 and 89. 3, respectively. The microcosmic force between CA membrane and CA membrane was from weak to strong. The order of microcosmic force between CA membrane and CA membrane was: ZnCl 2-2 containing nanoparticles, lactic acid-5% PVP-2 and CA membrane without additive. The effects of nano-particles such as fCNT _ (2) TIO _ (2) and SiO2 on BSA pollution resistance of CA membrane were better than those of traditional additives ZnCl _ (2) and lactic acid (SiO2).
【学位授予单位】：西安建筑科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TQ051.893

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