氧化石墨烯骨架调控支撑层微结构的正渗透复合膜制备及其应用

Forward osmosis (FO) has recently received increased attention as an emerging desalination technology of membrane separation due to its potential advantages including less operation energy, low fouling tendency and high rejection to contaminants. However, the shortage of semi-permeable membranes with high water fluxes becomes the bottle-neck of the development of FO. A proper design for the substrate layer morphology of asymmetric membrane are essential to effectively reduce the internal concentration polarization (ICP) in the porous substrate and therefore improve the water flux of membrane. ICP is a dominant factor on the water flux in FO process. This project aims to develop a novel substrate modulated by graphene oxide frameworks (GOF) for thin film composite (TFC) FO membrane. The desired GOF materials in favor of the improvement of membrane morphologies are designed and fabricated. The special structure of prepared membranes is beneficial to accelerate the diffusion coefficient and decrease the distance of draw solute from solution bulk to the interface of active layer and porous substrate. The properties of membranes will be systematically investigated, such as the wettability (surface energy), structure parameter, permeability (water flux, rejection to the feed solute, reverse leakage rate of draw solute, fouled potential and stability, etc.) besides the practical performance in seawater desalination. Furthermore, a mass transport model taking into account the effect of membrane materials physiochemical properties and micro structure on process performance will be established to identify the main parameters on the osmotic properties of membrane based on the experimental data. This study will provide a new idea and protocol and to prepare high performance FO-TFC membrane in the future.

正渗透(FO) 是一种新兴的膜分离脱盐技术，因其具有低能耗、低污染、对污染物有广泛的截留能力等潜在优势而倍受关注。然而，高水通量半透膜的缺乏成为这项技术发展的瓶颈。非对称膜多孔支撑层内严重的内浓差极化(ICP)是影响膜通量的主要因素，而合理的基膜结构设计可有效地减弱ICP，对提高通量而言至关重要。本项目从膜的结构设计出发，拟开展氧化石墨烯骨架(GOF)材料的设计与制备并将其应用于复合膜支撑层结构的调控，提高溶质在支撑层内的传递速率，缩短溶质的扩散路径，开发新型低结构参数正渗透复合膜。除以海水淡化为背景评估膜在实际应用中的性能外，还将系统考察膜的润湿性（表面能）、结构参数、渗透性能（水通量、溶质截留率、提取剂的反向渗漏率、抗污性及化学稳定性）。了解膜的物化性质、微观结构与正渗透通量之间的关系，建立相应的传质模型，明确影响膜通量的主要因素，为制备高性能FO复合膜提供新的方法和思路。

正渗透(FO) 是近十余年被广泛关注的膜分离技术，因其具有低能耗、低污染、对污染物有广泛的截留能力等诸多潜在优势。然而，高水通量半透膜的缺乏成为这项技术发展的瓶颈。非对称膜多孔支撑层内严重的内浓差极化(ICP)是影响膜通量的主要因素，而合理的基膜结构设计有效地减弱了ICP，对提高通量而言至关重要。本项目从膜的结构设计出发，开展氧化石墨烯骨架(GOF)系列材料的设计与制备并将其应用于复合膜支撑层结构的调控，提高溶质在支撑层内的传递速率，缩短溶质的扩散路径，开发新型低结构参数正渗透复合膜。系统考察了膜的润湿性（表面能）、结构参数、渗透性能（水通量、溶质截留率、提取剂的反向渗漏率、抗污性及化学稳定性）。了解膜的物化性质、微观结构与正渗透通量之间的关系，明确影响膜通量的主要因素，为制备高通量的FO复合膜提供新的途径。结果表明，以GOF为主体结构的正渗透膜，尽管通量在某些条件下，能获得较高值，但在水溶液中结构稳定性较差。掺杂型复合膜中改性粒子不仅能提高膜的分离性能，且在操作过程中膜结构和性能等都比较稳定。