Abstract:

With the rapid development of industry, increasing attention has been paid to the efficient separation of organic solvents by nanofiltration membranes. However, nanofiltration membranes are difficult to be further industrialized because of the trade-off effect between flux and selectivity. In this paper, hydrophobic g-C₃N₄ nanosheets and hydrophilic amylose (AM) were used as building units to prepare heterostructure g-C₃N₄@AM lamellar membrane by double needle electrostatic atomization. The hydrophilic amylose promotes the dissolution of polar solvents and the hydrophobic g-C₃N₄ nanosheets provide the low resistance diffusion of polar solvents. Therefore, this heterostructure structure greatly enhances the permeation of the membrane to polar solvents without reducing the separation ability. Compared with g-C₃N₄ membrane, the g-C₃N₄@AM membranes show 1—2 times higher polar solvent permeance. Simultaneously, the g-C₃N₄@AM membranes accomplish 99% rejections towards dye molecules with sizes above 1.5 nm. After long-term operation, pressure cycle and acid-base stability test, the variation of solvent permeance and dye rejection is below 6%, which demonstrate that this hydrophilic/hydrophobic heterostructured lamellar membrane shows great operating stability.

Key words: heterostructure, electrostatic atomization, amylose, membrane, nanofiltration, separation

摘要：

随着化工行业的迅速发展，利用纳滤膜对有机溶剂进行高效分离受到了越来越多的关注，但有机溶剂纳滤膜通量和选择性之间普遍存在 trade-off 效应的限制。以相对疏水的g-C₃N₄纳米片和亲水的直链淀粉（amylose，AM）为构筑单元，利用双针头静电雾化技术制备了异质结构的g-C₃N₄@AM 层状膜。亲水的直链淀粉促进了极性溶剂的溶解，相对疏水的g-C₃N₄纳米片实现了通道对极性溶剂的低阻力扩散；两者协同，极大地增强了膜对极性溶剂的渗透性能，而不降低分离能力。与纯g-C₃N₄层状膜相比，g-C₃N₄@AM 层状膜对极性溶剂的渗透系数提高了1~2倍，对于尺寸大于 1.5 nm 的染料分子可以实现 99% 以上的截留率。在操作稳定性、压力循环和耐酸碱测试后，膜的渗透性能和截留能力基本保持不变，衰减 < 6%，具有较好的操作稳定性。

关键词: 异质结构, 静电雾化, 直链淀粉, 膜, 纳滤, 分离