高选择性环境友好型壳聚糖分离膜的制备和应用研究

Preparation and Applications of an Environmentally Friendly Chitosan Membrane with High Selectivity

杜东宇

11930308

硕士

材料工程

刘鑫

2021-05-14

2021-05-28

南方科技大学

深圳

开发基于天然高分子材料和绿色合成工艺的高选择性环境友好型分离膜对膜技术的可持续发展具有重要意义。本研究选取天然高分子壳聚糖材料，采用“碱—尿素”低温冻融的绿色溶解体系配制壳聚糖铸膜液；使用湿法铸膜制备壳聚糖分离膜，并通过调控成膜条件（凝固浴种类和温度）优化壳聚糖分离膜的性能，获得可用作基膜的壳聚糖分离膜；经实验筛选，当采用-20℃无水乙醇为凝固浴时，所制备的壳聚糖基膜表面相对致密、机械性能显著提高、并兼具较高的水通量（~40 LMH）和截留率（对1 μm聚苯乙烯微球和大分子有机物牛血清蛋白的截留率分别为96.0±2.0%和98.4±1.7%）。选用三氯化铁和单宁酸（TA）配位体系，采用溶液混合和配合物聚集体自沉降的方式在壳聚糖基膜表面构筑“铁—单宁酸（Fe-TA）”选择层、合成壳聚糖复合薄膜；结合膜分离性能测试和物化特性表征，从反应溶液的金属—配体比例、金属—配体浓度、酸碱度和沉降时间等四个方面对选择层制备条件进行优化；并在Fe和TA摩尔浓度为7.2 mM和2.4 mM、TA溶液中NaOH浓度为28.8 mM且沉降时间为24 h时，成功制备出水通量为12.5±2.4 LMH、对小分子染料甲基橙截留率达到88.4±7.1%，并对水中多种低浓度抗生素截留率超过97%的高选择性天然高分子分离膜。采用此方法获得的环境友好型壳聚糖分离膜的通量可与商品纳滤膜相媲美，并可有效弥补现有高选择性分离膜难以有效去除水中低浓度抗生素类物质的不足。

The fabrication of environmentally friendly membranes with high selectivity based on natural materials via green synthesis processes is of great importance in the sustainable development of membrane technology. In this study, a chitosan dope solution was prepared using an alkali-urea solution with a series of freezing-thawing cycles. Corresponding chitosan membranes were fabricated via wet casting and optimized by adjusting the phase inversion conditions, especially the components and temperature of the coagulation bath. The optimized chitosan membrane obtained with -20℃ ethanol coagulation bath has superior water permeability (~40 LMH) and selectivity (96.0±2.0% and 98.4±1.7% for polystyrene particles with a diameter of 1 μm and bovine serum albumin, respectively). It also has improved mechanical strength and a relatively dense surface, which could be employed as a substrate of the high-performance natural polymer membrane. A selective layer was synthesized on the chitosan substrate by implementing green coordination chemistry using ferric chloride and tannic acid. The properties of the selective layer were optimized via four aspects, the ratio of the coordination center and ligands, the concentration of ferric chloride and tannic acid solution, the pH value, and the duration of immersion. A high selective chitosan membrane was harvested by immersing the substrate in the mixture of 7.2 mM ferric chloride solution and 2.4 mM tannic acid solution (containing 28.8 mM NaOH) for 24 h. The synthesized high selective chitosan membrane has a water flux of 12.5±2.4 LMH (at 1 bar applied pressure) and a methyl orange rejection of 88.4±7.1%. The chitosan membrane exhibits outstanding selectivity to varieties of antibiotics (up to 97%). The performance of the high-hyphenselective environmentally friendly chitosan membrane is comparable to that of commercial nanofiltration membranes. Besides, it shows superior separation efficiency of the wastewater containing antibiotics with a low concentration, which can be considered complimentary to the current high selective membrane.

天然高分子 相转化 绿色配位化学 纳滤 抗生素去除

natural polymer phase inversion green coordination chemistry nanofiltration removal of antibiotics

中文

独立培养

南方科技大学

杜东宇. 高选择性环境友好型壳聚糖分离膜的制备和应用研究[D]. 深圳. 南方科技大学,2021.