【作者】 王海芳；

【导师】 王连军；

【作者基本信息】 南京理工大学 ， 环境工程， 2006， 博士

【摘要】 本文研究了基于超分子化学作用的多孔聚偏氟乙烯(PVDF)膜的表面亲水改性及其在处理低浓度含油废水中的应用。 首先，提出了基于超分子化学作用的多孔PVDF膜表面亲水改性的机理。超分子化学作用是基于分子间的非共价键相互作用而形成的分子聚集体的化学，主要研究两个或多个分子通过分子之间的非共价键的弱相互作用，如氢键、范德华力、偶极／偶极相互作用、亲水／疏水相互作用及它们之间的协同作用而生成的分子聚集体的结构和功能。作为超分子化学中的一个分支，层状组装超薄膜的构筑和功能化一直是超分子科学研究中的热点，层状组装超薄膜的成膜推动力有静电力、氢键、配位键、电荷转移、范德华力、π-π相互作用、分子识别或上述几种作用力的协同。尽管上述都是弱相互作用力，强度不大，但这些弱相互作用力叠加的结果足可以维持所获得的组装体的稳定性。氢键的形成在超分子化学中有着重要的地位，许多超分子结构是通过氢键形成的。有研究结果表明，在不存在空间阻力、电荷转移、堆积相互作用等其它效应时，结合能同氢键数目线性相关。PVA的结构式中存在—OH，其中的氢原子具有较强的活性，而PVDF的结构中存在电负性很大，原子半径很小的氟原子，当具有较强的活性的氢原子遇到电负性很大的氟原子时，由于静电力的作用而形成氢键：F…H—O，而使PVDF的表面通过氢键作用而形成一层亲水的PVA复合层。 为了确保所形成的亲水层的稳定性，利用酸性条件下的醇醛交联反应，使PVA分子与戊二醛发生部分交联，在保证改性后膜的亲水性的前提下，可以使改性膜的表面层稳定存在，同时交联网状聚合物结构还可以改善改性膜的热稳定性和机械性能。 研究了影响膜改性效果的主要因素，以纯水通量和水接触角作为考核指标，确定了多孔PVDF膜表面亲水改性的最佳实验条件，所制得的改性膜表面具有较强的亲水性，改性膜的水接触角由原PVDF膜的117°减小到35°以下，在操作压力低于0.2MPa时，纯水通量由原PVDF膜的0增加到130L／m~2h以上(以杯式膜分离器死端方式测得)。改性膜的油截留率显著增大。与原PVDF膜比较，改性膜的热稳定性和机械稳定性都略有改善。 对制得的改性膜进行了表面分子结构表征。改性膜的表面—OH和—F共存，而且—OH以游离、分子间缔合和分子内缔合三种形式存在，其中缔合羟基大量存在于改性膜表面，说明存在基于氢键的分子间作用。通过比表面测定和扫描电镜观察，改性膜的孔径分布变窄，且膜的表面更趋于光滑。 用静态吸附法考察了改性膜对油滴的吸附性，膜对油分子的吸附属一级动力学吸附，且吸附过程的主要控制步骤是油分子在膜表面及膜孔内的扩散速度，因此，对膜做表面亲水改性，减小膜与油分子间的作用力是控制油分子在膜上吸附的有效途径。更多还原

【Abstract】 In this dissertation, a research has been made on the surface hydrophilic modification of porous polyvinylidene fluoride（PVDF） membrane based on supramolecular chemistry process and its application in the treatment of low concentration oily wastewater.First, the mechanism of surface hydrophilic modification of PVDF membrane based on supramolecular chemistry process has been presented. Supramolecular chemistry is the chemistry of ordered arrays of molecular units based on non-covalent weak interactions; it mainly studies the structure and function of the molecular assembly which are formed through the non-covalent bond weak interaction between two or among more molecules, such as hydrogen bond, van der waals force, dipole/dipole interaction, hydrophilic/hydrophobic interaction and their synergistic reaction. As a branch of supramolecular chemistry, the construction and function of the layer assembly of ultrathin membrane has been the hot issue to be studied. There are many kinds of impetuses to prepare ultrathin film by alternant sediment technique, such as electrostatic force, hydrogen bond, coordination bond, charge transfer, van der waals force, π-π interaction, molecular recognition or the synergistic reaction of several forces above. Though those all are weak interaction forces and the intensity is not strong, the total force is strong enough to preserve the stability of assembly system if these weak interactions are accumulated.Taking the water contact angel and pure water flux as the performance indexes, the main influence factors on performance of modified membrane are researched, and the main experimental conditions of membrane modification are determined. After modification, the water contact angle is 35° and pure water flux are over 100Lm^-2h^-1, which are improved greatly compared to the PVDF membrane, and the oil rejection ratio is increased dramatically. Moreover, the thermal stability and the mechanical stability of modified membrane is slightly increased.In order to ensure the stability of surface layer, the partial cross-linking reaction happened between glutaraldehyde and PVA which was on PVDF membrane by hydrogen bond, which not only insure the hydrophilicity of PVDF membrane, but also improve the stability of modified membrane.Taking advantage of Fourier transform infrared spectrum and X-ray photoelectron spectroscopy, the researcher has conducted a contrastive research on the surface molecular structure of porous PVDF membrane before and after modification. Research results indicate that, though the C-F characteristic peak of the PVDF membrane still exists after更多还原