Abstract:

Microporous polymer membranes resistant to various organic solvents have gradually attracted attention in the field of organic nanofiltration. Herein, we report a covalent triazine framework membrane (CTF-BP) synthesized by a super acid-catalyzed organo-sol-gel reaction of commercially available aromatic nitrile monomer. This membrane exhibits good mechanical strength and is dimensionally stable in organic solvents, such as methanol, n-hexane, etc. Size sieving by the robust micropores (<1.0 nm) confers the membrane with a cut-off molecular weight as low as 550. The hydrogen interaction between triazine rings and the hydroxyl groups facilitates the transport of methanol, the flux of which reaches up to 1.10 L/(m²·h·bar), a value much higher than that of the less viscous n-hexane [0.23 L/(m²·h·bar)]. To demonstrate the practical applicability, this membrane is utilized to separate n-hexane containing low concentration of methanol solution [5% (mass) methanol], and a maximum separation factor of 1485 and a methanol flux of 3.21 kg/(m²·h) are obtained. These results demonstrate the great potential of the CTF-BP membranes in the recovery of methanol from its mixture with n-hexane via organic solvent nanofiltration (OSN).

Key words: covalent triazine framework, polymer membrane, organic solvent resistant, nanofiltration, methanol/ n-hexane separation

摘要：

具备耐各种有机溶剂的微孔聚合物膜在有机纳滤领域逐渐受到重视。采用双氰基单体的超酸催化成环聚合反应，制备微孔框架聚合物薄膜(CTF-BP)，该膜具备良好的力学性能，可耐受甲醇和正己烷等常见有机溶剂。CTF-BP膜内大量<1.0 nm的微孔通道使膜具备良好的筛分性能，其截留分子量为550。膜内含有的三嗪结构与羟基具有较强的亲和性，使甲醇的跨膜通量［1.10 L/(m²·h·bar)］显著高于黏度更低的正己烷通量［0.23 L/(m²·h·bar)］。采用纳滤操作将膜用于分离含低浓度甲醇的正己烷溶液［含5%(质量)甲醇的正己烷溶液］，结果显示甲醇/正己烷分离因子最高可达到1485，渗透液的总流量超过3.21 kg/(m²·h)。证实CTF-BP膜有望实现高效甲醇/正己烷分离。

关键词: 三嗪框架, 聚合物膜, 耐有机溶剂, 纳滤, 甲醇/正己烷分离