Nanofiltration (NF) has the potential to achieve the efficient effluent separation. However, conventional polyamide-based NF membranes face several challenging issues, including negatively charged surface, insufficient water permeance and low selectivity of organic micropollutants. Herein, we designed a novel polyamine membrane generated from the nucleophilic substitution reaction between 1,4,7,10-tetraazacyclododecane (Cyclen) and 1,3,5-tris(bromomethyl)benzene (TBB), and proposed its fabrication via oligomer triggered interfacial polymerization (OT-IP). As the crucial component of the polyamine membrane, the amine-linked Cyclen-TBB selective layer was assembled onto a porous substrate through interfacial polymerization between alkaline aqueous solution and organic solution consisting of Cyclen and TBB premixed in n-hexane. The resultant Cyclen-TBB composite membrane possessed an effective pore size of ∼1.6 nm and strongly positively charged surface with a zeta potential of +18.4 mV in a neutral solution. Owing to these characteristics, the Cyclen-TBB composite membrane exhibited a high water permeance of 77.0 L·m −2 ·h −1 ·bar −1 , and high rejections to positively charged dyes and drugs with molecular weights above 500 Da. Moreover, the composite membrane possessed splendid chemical resistance under both acidic or alkaline conditions, and operational stability during continuous filtration. These results demonstrate that novel highly permeable and positively-charged polyamine NF membranes are potential candidates for selective separation of molecules, and provide a feasible alternative for application in the treatment of industrial and pharmaceutical effluents.
The fabrication of a scalable and economic acid-resistant polyamine-based NF membrane by a spray coating polymerization-based technique for heavy metals removal and acid wastewater treatment is herein reported for the first time. The process was optimized to produce a well crosslinked selective layer network membrane (named S C-TFC-N) with controlled thickness of ∼75 nm and effective mean pore radius of ∼6.2 Å. Two membranes having similar chemical compositions, christened S C-TFC-R and DC-TFC-N were also developed by reverse interfacial polymerization (RIP) spray coating and conventional dip-coating IP techniques, respectively for comparison. All the fabricated membranes displayed high rejections to divalent cations such as MgCl 2 (2000 ppm) reaching rejection up to 98.6 %, but the optimized S C-TFC-N membrane achieves a water permeance of 9.1 L m −2 h −1 bar −1 , which was about 1.7 and 1.4 times that of S C-TFC-R and DC-TFC-N membranes, respectively. Specifically, the S C-TFC-N membrane exhibits great stability under high salt concentrations, continuous filtration performance, and excellent fouling resistance after five-filtration stages. Consequently, the membranes displayed over 90 % rejections of the heavy metal ions, in the order of Pb 2+ > Zn 2+ > Cu 2+ , and also exhibit excellent acid resistance by maintaining high divalent cations salt rejection performances after being subjected to different acidic conditions. In addition, density functional theory (DFT) calculations carried out proved the stability of the polyamine NF membrane against nucleophilic and electrophilic attacks. This work thus demonstrates an efficient and sustainable approach for producing NF membrane with good potential application in heavy metal ions removal and acid mine drainage wastewater treatment.
危险品化学品经营许可证（带存储）