抗污染的高通量醋酸纤维素超滤膜的研究

发布时间：2018-04-22 08:43

本文选题：超滤膜 + 醋酸纤维素　；参考：《北京理工大学》2015年硕士论文

【摘要】：超滤技术是节能、高效、绿色的新型分离技术,被广泛应用于工业领域的分离、提纯和浓缩。但是,在超滤过程中出现的膜污染现象易导致通量下降,分离性能劣化。通过对超滤膜进行亲水性改性可以有效的提高膜的抗污染性能。本论文以醋酸纤维素(CA)为制膜材料,分别以PVP-b-PMMA-b-PVP、纳米纤维素晶须(CNW)和邻苯二甲酰化壳聚糖(NPHCs)等不同类型的亲水性物质为改性材料,采用浸没沉淀相转化法制备复合超滤膜。讨论了改性材料对共混膜性能产生的影响,探究膜的亲水性能、抗污染性能、力学性能以及热稳定性的改善情况。为提高CA膜的纯水通量及亲水性加入了两亲性嵌段共聚物PVP-b-PMMA-b-PVP,并对所制备的膜进行了表征及性能测试。结果表明,共混膜的孔径尺寸及表面粗糙度较纯CA超滤膜有所增加,且随着PVP-b-PMMA-b-PVP共聚物分子量或疏水链段的减小,孔径增大,粗糙度增加。由于亲水性链段PVP在膜表面的富集,共混膜的亲水性提高,接触角减小,纯水通量大幅提高,蛋白质截留率有所下降,但水通量恢复率提高,抗污染性能改善。采用亲水性的纳米纤维素晶须(CNW)改性醋酸纤维素超滤膜。CA/CNW共混超滤膜在纯水通量、含水量、孔隙率等方面有了大幅提高;共混膜的膜孔径尺寸增大,表面粗糙度增加。但是,膜孔径的大小及表面粗糙度随着CNW添加量的增加呈现先增大后减小的趋势。CA超滤膜的纯水通量由34.84 L·m-2 h-1提高至233.45 L·m-2 h-1,同时保持较高的蛋白质截留率。共混膜的亲水性提高,水通量恢复率从56.00%提高至96.73%,有效改善了CA超滤膜的抗污染性能。同时,共混膜的力学性能和热稳定性能增强。制备可溶于有机溶剂的NPHCs作为改性材料,并通过相转化法制备了CA/NPHCs共混超滤膜。实验发现,改性后的CA超滤膜大孔径结构增多,孔隙率增加,纯水通量增大,操作效率提高。同时,随着NPHCs和PEG600的加入,超滤膜的亲水性增加,水通量恢复率逐步提高,NPHCs可作为CA膜的有效改性材料。
[Abstract]:Ultrafiltration (UF) is a new energy-saving, efficient and green separation technology, which is widely used in the industrial field of separation, purification and concentration. However, membrane fouling in ultrafiltration process leads to flux decline and separation performance deterioration. The hydrophilic modification of ultrafiltration membrane can effectively improve the antifouling performance of the membrane. In this paper, the composite ultrafiltration membrane was prepared by immersion precipitation phase transformation method with different hydrophilic materials such as PVP-b-PMMA-b-PVP (nano-cellulose whisker CNW) and phthalic acylated chitosan (NPHCs) as membrane materials. The effects of the modified materials on the properties of the blend membranes were discussed. The hydrophilicity, antifouling, mechanical properties and thermal stability of the membranes were investigated. The amphiphilic block copolymer PVP-b-PMMA-b-PVP was added to improve the pure water flux and hydrophilicity of CA membrane. The results show that the pore size and surface roughness of the blend membrane increase with the decrease of molecular weight or hydrophobic chain segment of the PVP-b-PMMA-b-PVP copolymer, and the pore size increases and the roughness increases with the decrease of the molecular weight or hydrophobic chain segment of the PVP-b-PMMA-b-PVP copolymer. Because of the enrichment of hydrophilic PVP on the membrane surface, the hydrophilicity of the blend membrane increased, the contact angle decreased, the pure water flux increased significantly, the protein rejection rate decreased, but the water flux recovery rate increased and the anti-pollution performance improved. Cellulose acetate ultrafiltration membrane modified by hydrophilic nano-cellulose whisker (CNW). CA / / CNW blend ultrafiltration membrane has a significant increase in pure water flux, water content and porosity, and the pore size of the blend membrane increases and the surface roughness increases. However, the pore size and surface roughness of the membrane increased firstly and then decreased with the increase of CNW content. The pure water flux of CA ultrafiltration membrane increased from 34.84 L m -2 h -1 to 233.45 L m -2 h-1, while maintaining a high protein retention rate. The hydrophilicity of the blend membrane was improved, and the water flux recovery rate was increased from 56.00% to 96.73%, which effectively improved the anti-fouling performance of CA ultrafiltration membrane. At the same time, the mechanical properties and thermal stability of the blend film were enhanced. NPHCs, soluble in organic solvent, was prepared as modified material, and CA/NPHCs blend ultrafiltration membrane was prepared by phase inversion method. The experimental results show that the modified CA ultrafiltration membrane has more large pore structure, higher porosity, higher water flux and higher operating efficiency. At the same time, with the addition of NPHCs and PEG600, the hydrophilicity of ultrafiltration membrane increased, and the recovery rate of water flux increased gradually.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ051.893

【相似文献】