COF Filters out Small Organic Molecules from Water

COF Filters out Small Organic Molecules from Water

Porous materials might help wastewater treatment plants remove pharmaceuticals from sewage.

A new filter membrane based on a covalent organic framework (COF) could help clean up drug-laden wastewater ( Angew. Chem. Int. Ed.  2018, DOI: 10.1002/anie.201802276).

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A COF filter removed organic dyes from water. In each pair, the left tube is before filtration and the right is after. The dyes used are chrome black T (from left), methyl blue, Congo red, acid Fuchsin, and rose Bengal. Credit: Angew. Chem. Int. Ed.

The medicines we take often end up in sewage. Wastewater treatment plants struggle to remove these compounds before releasing water back into the environment. Scientists worry that when these molecules end up in the environment, they might contribute to the spread of antibiotic resistance or disrupt development in aquatic animals.

COFs are crystalline porous networks made from small organic elements covalently linked together. They are similar to metal-organic frameworks (MOFs), which are finding uses in hydrogen storage and catalysis. COFs have been used in similar applications, but Jürgen Caro of Leibniz University Hannover thought the materials could make good nanofilters.

In fact, the tunable pore sizes of COFs make them prime candidates for separation technologies. Caro and his team used a well known imine-based COF, called COF-LZU1, developed at Lanzhou University. The pores in COF-LZU1 are 1.8 nm in diameter, which is small enough to block most pharmaceutical molecules.

Many drug compounds are bigger than 1.8 nm wide. Another advantage of this imine-based COF is its stability in water.

Read full article: Chemical & Engineering News