同质增强PPTA中空纤维复合膜结构设计与粘胶纤维废水处理研究

Viscose fiber is an important product in textile industry of our country, which is second to polyester fiber (PET) production. It has a lot of excellent properties such as a better hygroscopicity, suitable fabrication process and biodegradation. However, it has also several serious disadvantages including excessive emissions, high acid and alkaline concentration, and complex composition, which is difficult to handle. At present, the physical-chemical treatment processes are unable to achieve effective governance, and the porous membrane materials are applied to treat this kind of severe wastewater through membrane separation technology, which is limited to the ceramic membrane. It has a great corrosion resistance against with complex preparation, low loading density and expensive. In order to overcome the disadvantage of the poor mechanical properties, inferior chemical anti-corrosion and anti-pollution for a majority of currently available organic porous membrane. In this research project, it will integrate homogenous fiber reinforcement and interfacial polymerization with conductive polymers surface modification. The novel homogenous reinforced PPy/PPTA hollow fiber composite membrane is prepared with high strength, superior chemical anti-corrosion and anti-pollution, and excellent interfacial bonding for the first time. Then, it will be studied on the state between these two interfacial bonding among fiber reinforced matrix, surface layer and thin film composite layer, Moreover, it will be studied on the synergistic effects of membrane micro-pore separation and conductivity for control membrane fouling. Then, it is indicates the relationship between functional membrane surface layer and separation performance as well as pollution control.

粘胶纤维是我国纺织工业中的重要产品，产量仅次于涤纶纤维，具有吸湿性好、易于纺织加工及可生物降解等优良性能。然而与此同时，它又存在污水排放量大、酸碱度高、成分复杂的问题，处理起来困难极大。目前国内采用的物化处理工艺无法达到有效治理，而采用膜分离技术应对此类工业重度污水处理的多孔膜材料，我国仅限于无机陶瓷膜，其具有优异的耐腐蚀性，但制备工艺复杂、装填密度低、价格昂贵。为克服现有大部分高分子多孔膜材料力学性能、耐化学腐蚀性能及抗污染性能较差的缺点，本项目首次将同质纤维增强、界面聚合与化学气相沉积相结合，即将膜力学性能增强、分离性能提高及导电高分子膜有机融为一体，制备兼具高强度、耐腐蚀、抗污染、高界面结合强度及分离精度的新型导电同质增强PPy/PPTA中空纤维复合膜。研究复合膜界面结合状态；研究复合膜微孔物理筛分与导电效应对控制膜污染协同作用；揭示构筑表面功能层结构与膜渗透分离的相互关系。

随着膜分离技术应用领域的不断拓展，特别是在化工、纺织、电子、生物医药等领域，对高性能膜材料的需求也越来越高。聚对苯二甲酰对苯二胺（PPTA）是一种典型的芳香族聚酰胺，分子链中含有大量的苯环和酰胺键结构，分子链具有较高的结晶度，从而赋予PPTA优异的亲水性能、力学性能、耐热性能及耐溶剂性能等优点。. 因此，本项目从高分子加工原理和新材料应用角度出发，将溶液液晶纺丝技术与纤维增强技术相结合，以纤维级PPTA为成膜聚合物，PPTA纤维编织管为增强体，通过干-湿法纺丝技术制备了具有高亲水、耐高温、耐溶剂、抗污染的同质增强型PPTA中空纤维膜。选用哌嗪（PIP）、均苯三甲酰氯（TMC）以及吡咯（Py）等材料，采用界面聚合法、化学气相沉积法等方法，对膜表面分离层结构进行设计，制备了高通量、耐高温、耐溶剂及高分离精度的PPTA复合纳滤膜。. 建立了调控表面分离层与纤维增强体之间界面结合状态、表面分离层多孔结构及聚集态结构的有效方法，建立表面/界面结构与中空纤维膜分离性能、力学性能、耐反洗性能及使用寿命的模型关系等关键基础性问题。同时结合界面聚合和化学气相沉积技术对所得复合膜表面功能层进行有序调控，构建具有类似“图灵”结构的致密层结构，探明了其成形过程中“反应-扩散”机制，其中，所得PPTA/PA/PPy复合纳滤膜对刚果红DMAc溶液的渗透通量大于20L·m-2·h-1·MPa-1，同时对刚果红截留率高达99.8%。球形簇状复合纳滤膜与条形簇状复合纳滤膜对PEG的切割分子量分别约为275Da和185Da，同时展现出了较高的脱盐性能，在保持Na2SO4高截留率的基础上（>98.6%），对NaCl截留率分别为62.5%和76.4%。为规模开发新一代耐高温、耐溶剂中空纤维复合膜材料提供科学依据及技术支撑。