Transport of Solutes and Macromolecules through Reverse Osmosis and Nanofiltration Membranes

0332217 码头 本研究的主要目的是阐明水污染物，从小的中性分子到大的高分子，通过反渗透和纳滤膜渗透的机制。选定的溶质和大分子是亚砷酸、阿特拉津（216道尔顿）、罗丹明WT（480道尔顿）和三种粒径范围为19至80 nm的大肠杆菌（fr、MS 2、T4）。该列表是由几个标准之间的妥协产生的，包括选择当前感兴趣的水污染物和用于评估RO/NF膜性能的替代物，已知被RO/NF膜拒绝的小溶质和大分子，以及用相对简单的无干扰分析技术在多溶质样品中可定量的化合物。该项目的工作范围旨在对水和各种类型的溶质通过RO和NF膜的渗透机制有一个基本的了解，包括阐明浓差极化现象在目标溶质和大分子的整体运输中的作用。为了实现这一目标，将进行渗透实验，以表征通过膜聚合物基质的吸附/扩散/解吸和通过膜纳米孔的平流对整体溶质/大分子渗透的贡献，以及浓差极化对两种类型渗透的影响。考虑的实验变量包括液压，背景和目标溶质浓度，温度，和pH值。然后，纳米孔的尺寸分布在反渗透和NF膜的活性层将其特征在于由原子力和扫描电子显微镜的组合，和气体吸附/解吸技术。预计表征RO/NF膜的孔径分布将需要整合这三种方法获得的结果。研究的最后一项任务将是开发一个机械模型，以代表水，溶质和大分子通过RO和NF膜的渗透。

0332217 Marinas The primary objective of this research is to elucidate the mechanisms by which water contaminants, ranging from small neutral molecules to large macromolecules, permeate through reverse osmosis and nanofiltration membranes. Selected solutes and macromolecules are arsenious acid, atrazine (216 Daltons), Rhodamine WT (480 Daltons), and three coliphages (fr, MS2, T4) ranging in size from 19 to 80 nm. This list resulted from a compromise among several criteria including the selection of water contaminants of current interest and surrogates used to assess the performance of RO/NF membranes, small solutes and macromolecules known to be poorly-rejected by some by RO/NF membranes, and compounds quantifiable in multi-solute samples with relatively simple interference-free analytical techniques. The scope of work of the project is designed to develop a fundamental understanding for the mechanisms responsible for the permeation of water and various types of solutes through RO and NF membranes including elucidating the role of the concentration polarization phenomenon in the overall transport of target solutes and macromolecules. In order to accomplish this goal, permeation experiments will be performed to characterize the contribution to overall solute/macromolecule permeation by sorption/diffusion/desorption through the membrane polymer matrix and advection through membrane nanopores, as well as the effect of concentration polarization on both types of permeation. Experimental variables under consideration include hydraulic pressure, background and target solute concentration, temperature, and pH. Then, the size distribution of nanopores in the active layers of RO and NF membranes will be characterized by a combination of atomic force and scanning electron microscopy, and gas adsorption/desorption techniques. It is anticipated that characterizing the pore size distribution of RO/NF membranes will require integrating the results obtained with these three methods. The final task of the study will be the development of a mechanistic model to represent the permeation of water, solutes and macromolecules through RO and NF membranes.