以石墨烯构建二维水通道正渗透膜与内浓差极化消除机理研究

A new bio-inspired graphene-based two-dimensional water channel forward osmosis membranes are first designed and fabricated by simulating the mechanism of draw water and desalination in China's aquatic plants (Salicornia) in this study. Based on it, the flow behavior of water molecules limited in graphene layers is explored, and to explain the Nano-lubricating Effect and two-dimensional Capillary Effect inspired by a single layer of water molecules, which provides a new idea and theoretical basis for solving the key problem of the concentration polarization in Forward Osmosis (FO) desalination technology and Pressured-Retarded Osmosis (PRO) technology. Two-dimensional water channel structure regulation between graphene sheet layers are achieved by changing ammoniated SiO2 nano particle size.And studies that the change of the flowing state of two-dimensional water molecular layers through regulation of the charge quantity of the SiO2 nano particles in the graphene sheet. With the methods of Frequency Doubling/ Combined Frequency, the relationship between the osmosis behavior of single water molecules layer between the graphene sheet and graphene charge quantity are discussed. And in view of that discussion on the role of non-chemical bond between two-dimensional water molecules (under the loss of three-dimensional hydrogen bond and with the residual potential) and the conjugatedπkey on graphene sheet layers, explain the effect of Nano-lubrication caused by two-dimensional water molecules layer. Fanilly, using this principle a high-flux FO membrane materials will be designed and fabricated,and investigate that some feature parameters of FO membrane,such as water flux, salt-ion rejection rate, back mixing rate in condition of taking betaines as draw liquid.The researches on the chemical and physical properties of single-layer water molecules in two-dimensional water channel based on graphene have important academic value and potential application value.

本研究受我国近海水生植物（海蓬子）脱盐取水机理启发，通过仿生设计并制备一种新型石墨烯基二维水通道正渗透膜，并以此膜为基础研究水分子受限于石墨烯片层之间的渗透流动行为，以解释单层水分子产生的纳米润滑效应和二维毛细效应，为解决正渗透（FO）海水淡化和压力阻尼渗透（PFO）发电上普遍存在的内浓差极化问题提供新思路和理论基础。本研究通过改变接枝到石墨烯上的氨化SiO2纳米颗粒的大小来实现对石墨烯二维水通道结构调控,并调控SiO2纳米颗粒的荷电量来改变水分子在石墨烯片晶间的流动状态；通过红外倍频/合频技术研究水分子在石墨烯片层间的含量变化，确定其与石墨烯通道内荷电量之间的关系；分析石墨烯片层上的共轭π键与具有残余势的二维水分子之间的非化学键作用，解释二维水通道内水分子的润滑效应。最终利用此原理设计并制备大通量FO膜材料。其单层水分子在二维水通道内的物理化学性质的研究具有重要的学术价值和潜在应用价值。

本研究受我国近海水生植物（海蓬子）脱盐取水机理启发，通过仿生设计并制备一种新型石墨烯基二维水通道正渗透膜，并以此膜为基础研究水分子受限于石墨烯片层之间的渗透流动行为，以解释单层水分子产生的纳米润滑效应和二维毛细效应，为解决正渗透（FO）海水淡化和压力阻尼渗透（PFO）发电上普遍存在的内浓差极化问题提供新思路和理论基础。项目研究制备了石墨烯基纳米复合FO膜皮层材料。以氧化石墨烯（GO）与正硅酸乙酯（TEOS）为原料，制备了不同粒径大小的GO-SiO2纳米复合材料，以聚砜为基体通过层层自组装（LbL）的方式，制备了片层状结构的石墨烯基FO复合膜。利用ATR-FTIR，XPS，XRD，Zetasizer Nano和SEM研究了复合材料化学结构，膜尺寸与表面形貌。并以NaCl溶液为汲取液（浓度2 M），去离子水为原料液研究了FO复合膜的分离性能。结果表明，SiO2可以成功接枝在GO的表面，SiO2既可以增大GO片层之间的水通道，也可以对皮层膜起到交联作用。酸性条件下生成的GO-SiO2的粒径较大，制备得到的复合膜GO层间的片层通道也越大。较大的层间距可以提高膜的水通量，但会显著降低对盐离子的截留率。酸性反应条件下（pH=4.0）制备的GO-SiO2膜具有较好的水通量（39 L•m-2h-1）和截留率（86%）。且复合膜中GO-SiO2的层数对膜的水通量影响不大，但层数越多，膜对盐离子的截留性能越好。复合膜中GO-SiO2的荷电量对膜的水通量影响较大，高荷电对盐离子的截留性能越好。最后探讨了水分子在二维水通道内的流动行为，对减少ICP的效果进行了分析。最终利用此原理设计并制备大通量FO膜材料。其单层水分子在二维水通道内的物理化学性质的研究具有重要的学术价值和潜在应用价值。