【作者】 王枢；

【导师】 陈文梅；

【作者基本信息】 四川大学 ， 化工过程机械， 2004， 博士

【摘要】 含油废水作为一种常见的污染源，其对环境保护和生态平衡危害极大；而水是生产和生活的重要资源，因此含油废水的油水分离是十分重要的。传统的含油废水处理方法有的分离效率不高，有的由于添加过多化学药剂使物料二次污染，还有的能耗过高、费用高昂。为弥补这些不足，近年来膜分离技术开始运用于含油废水的处理，其主要用于分离稳定的乳化油，具有能耗低、分离效率高、装置小等优点。在使用膜分离法处理含油污水时，膜污染和浓差极化引起的分离性能下降制约了其技术潜力的发挥。因此，抗污染油水分离膜的研制具有十分重要的理论和实际意义。 本文在国内外首次制备了用于油水乳化液分离的聚哌嗪酰胺／聚乙烯醇复合膜。该复合膜具有三层结构，包括多孔陶瓷(或聚乙烯)管式基膜、聚醚砜(或聚偏氟乙烯)超滤膜支撑层和聚哌嗪酰胺／聚乙烯醇复合功能层。超滤膜支撑层通过相转化法涂覆在多孔陶瓷管式膜上，复合功能层通过界面聚合法制备在超滤膜支撑层上。本文用FT-IR、SEM、XPS、SAXS和AFM对复合膜的结构进行了表征，较系统探索了复合膜支撑层的制备；复合膜支撑层和基膜对复合膜油水分离性能的影响；以聚偏氟乙烯(PVDF)为支撑层的复合膜功能层制备及其对分离性能的影响：以聚醚砜(PES)为支撑层的复合膜功能层制备及其对分离性能的影响；并在实验基础上建立了复合膜的水通量和截留率的经验公式，最后采用溶剂浸泡失重法研究复合膜在各种溶剂中的化学稳定性，取得了创新性的成果。 在复合膜的研究中，高性能的支撑膜是制备高性能复合膜的基础。本文选用PES和PVDF作为制备复合膜支撑层的膜材，以PES为代表探讨了制备复合摘要膜支撑层中影响支撑层结构的各种因素的作用。随铸膜液中PES浓度的增加，形成的膜孔径愈加致密，为获得孔径分布良好的PES支撑层，PES浓度应选择在10%以上。铸膜液抽真空时间延长、凝胶浴氯化纳含量的增加、凝胶浴温度的下降、溶剂挥发时间延长，热处理温度的上升都会导致支撑层孔径变小。支撑层孔径和孔隙率会随添加剂聚乙二醇(P EG)含量的增加而减小，支撑层内部将形成指状孔。支撑层孔径和孔隙率会随添加剂氯化铿(LICI)含量的增加而增加，支撑层内部将形成海绵状孔。同时加入这两种添加剂，支撑层孔径可通过PEG和LICI的比例进行调整，支撑层内部具有良好的指状孔结构，有利于复合膜水通量增加。 探讨了复合膜支撑层和基膜对纯水和油水乳化液在不同操作条件下的分离性能，以确定其对复合功能层的影响。提高操作温度有利于基膜水通量的增加，但实际工作温度应该考虑到复合功能层和支撑层的耐温性能。同一种基膜的孔径大小对复合膜分离性能影响很小。在0.1一0.4 MPa操作压力范围内，不同压力下的支撑层水通量呈良好的线形关系，且支撑层水通量随时间的变化趋势一致，因此可以认为操作压力在0.4 MPa以内不会对支撑层结构产生影响。支撑层表面孔径尺寸的选择应在保证复合膜功能层无缺陷的前提下尽可能大。 为制备小孔径、亲水性油水分离膜以提高油水乳化液中油的截留率和增加膜分离含油污水时的抗污染性，本文选用对苯二甲酞氯( TC)和呱嗓(PA)作为界面聚合的反应单体，并在水相添加聚乙烯醇(PVA)，共同在PVDF支撑层上反应构成复合膜的功能层，使用FT-IR、SEM、XPS和AFM对复合膜的形貌、组分进行分析，研究了制备复合膜功能层的各主要影响因素及其对分离性能的影响。PVDF支撑层的表面孔径随PVDF浓度的增加而减小。PVDF浓度过小，复合膜形成后缺陷多，截留率低;PVDF浓度过大，形成的复合膜水通量小。实验证实10%PVDF浓度支撑层的复合膜油水分离效果在水通量和截留率两方面都是最佳的。随呱嗦浓度增加，复合膜的水通量减小，截留率提高，复合膜表层接触角相应增加，复合膜的功能层也更加致密，呱嗦浓度高低对复合膜表面粗糙度影响不大。随TC浓度增加，复合膜功能层致密程度提高，截留率保持在高水平，同时还能使更多的PVA与之结合，增加复合膜的亲水性，降低膜污染，增加水通量。TC浓度对复合膜表面粗糙度影响很大，随浓度增摘要加，表面粗糙度增大，表面粗糙度的增加会增加膜面实际的过滤面积，从而增加水通量。随PVA浓度的增加，复合膜水通量下降，当PVA浓度高于60叭后，水通量下降幅度不大，复合膜亲水性变化很小。PVA浓度过高，复合膜功能层表面会形成PVA凝胶层，增大复合膜水力阻力，减小水通量。随反应温度上升，复合膜的接触角成线形下降，但下降幅度很小，亲水性提高不大。通过AFM对复合膜表面分析，PVDF支撑层上界面聚合复合膜的温度不宜超过50℃。实验证实复合膜具有良好的油水分离性能，无论水通量，还是截留率都优于PVDF超滤膜。 为进一步提高复合膜油水分离性能，用亲水性较好的PES作为复合膜的支撑层，同样选用TC和PA作为界面聚合的反应单体，并在水相添加PVA共同在PES支撑层上反应构成复合膜的功能层。通过SEM观察复合膜在不同反应温度下的形貌变化，并考虑复合膜的亲水性，定出20℃是适合PES支撑层的制膜温度。以PES为支撑层制备复合膜，PVA浓度低于以PVDF为支撑层的复?更多还原

【Abstract】 Oily wastewater is a common pollution in the world which has lot of harm to environments, whereas water is important source of living and production. Thus, separation of oily wastewater is very important. Traditional treatments for oil/water separation had low efficiency or consumed lots of energy. In some case, water had been polluted by chemical additive. In recent years, membrane technologies have been successfully applied for treating oil/ waste emulsion which could supply a gap of those traditional treatments. However, the performances of membrane separation are limited by the membrane fouling and concentration polarization. Therefore, development of antifouling membranes is a most pressing task at present.A novel fouling-resistant polyamide/polyvinyl alcohol (PVA) composite membrane was developed for removal of oil-in-water (O/W) emulsions. The composite membrane was featured with an asymmetric three-layer structure, i.e., a tubular porous ceramic (or polyethylene) membrane, a polyethersulfone (or polyvinylidene fluoride) ultrafiltration substrate, and a polyamide/ PVA composite thin top-layer. The PES (or PVDF) polymer was cast onto the tubular porous ceramic (or PE) membrane with a sol-gel method, and the polyamide/PVA composite thin top-layer was fabricated with an interfacial polymerization method. FT-IR, SEM, XPS, SAXS and AFM were employed to characterize the composite membrane. In this study, investigations were systematically carried out on preparation of composite membrane and substrate of composite membrane. Separation performance of composite membrane had been also investigated, and some exciting results have been gotten.A composite membrane is based on the substrate which should haveappropriate size, density, distributing of its pore and good chemical stability. PES and PVDF had been chosen as substrate of composite membrane in this study. The factors of preparing PES substrate had been investigated. The average pore size of substrate was smaller when PES concentration was increased in casting solution, and the result of experiments shows PES concentration should be higher than 10% for good structure of substrate. Prolonged vacuuming time of casting solution and volatile time of solvent were leading smaller average pore size of substrate. The average pore size of substrate was smaller when sodium chloride concentration was increased or ethanol concentration was decreased in casting solution. The average pore size was of substrate bigger when temperature of coagulation bath was decreased or temperature of heat treatment was increased. Lithium chloride (LiCl) and Polyethylene glycol (PEG) were employed as additives in the casting solution, in order to obtain desired membrane pore size for separation. The average pore size of substrate was smaller when PEG concentration increased, and the result was reverse as LiCl instead of PEG. The fingerlike hole appeared in interior of substrate when LiCl and PEG were employed together in casting solution. And this structure of substrate was availed to flux of composite membrane.Investigations of pure water and oil/water emulsion separation performance in different operation condition of PES (PVDF) substrate of composite membrane and tubular porous ceramic (or PE) membrane were carried out. The increasing of operating temperature would increase flux of tubular porous membrane. The change of pore size of same kind of tubular porous membrane had little effect on flux of composite membrane. The operating pressure which less than 0.4MPa wouldn’t destroy the structure of substrate of composite membrane. The average pore size of substrate should be as big as possible when there was no disfigurement in top-layer of composite membrane by using the substrate.A small average pore size, high hydrophilic polyamide/PVA composite membrane based on PVDF substrate was prepared by using the method of interfacial polymerization for separating drastically emulsified oil/water emulsions. TC wasorganic monomer and PA was aqueous monomer. The aqueous solution was also in更多还原