The increasing global demand for safe drinking water and environmental concerns about current treatment methods have inspired research and development of novel treatment approaches including membrane technologies. Nanofiltration (NF) and reverse osmosis (RO) are the most commonly used membrane processes for drinking water treatment because they offer an effective single-step process for removing pathogens along with organic and inorganic contaminants. Despite its advantages and recent technical advances, the high cost of energy and membrane operational problems associated with fouling and fouling control strategies limit widespread implementation of NF and RO technologies. As an alternative to conventional polymeric membrane materials, which are susceptible to (bio)fouling, compaction, and chemical degradation by oxidizing agents used to prevent biofouling, covalent organic frameworks (COFs) are a promising class of materials for membrane processes. COFs are constructed from modular blocks to form crystalline, permanently porous materials. Employing COF active layers in the asymmetric membrane structure should result in uniform pores with tailored size, shape, and designed chemical functionality in contrast to the semi-amorphous and empirically optimized polyamide active layers that currently dominate the field. This work investigates the use of a COF thin film based on imine linkages as an alternative membrane material. Rutherford backscattering spectrometry (RBS) analyses indicate the presence of a ~10 nm thick polyimine film after interfacial polymerization on top of an ultrafiltration membrane support. The COF active layers supported by the ultrafiltration membrane provide enhanced rejection of Rhodamine-WT, a surrogate for organic contaminants, and NaCl in comparison to the support layer alone. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and atomic force microscopy (AFM) analyses will also be presented.

Covalent organic frameworks as novel membrane materials

253rd National Meeting (2017)

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