Open-Cell Robust COF-Nanowire Network Sponges as Sustainable Adsorbent and Filter

Constructing crystalline covalent organic frameworks (COF) robust 3D reusable macroscopic objects exposing more adsorption sites with high water flux for use as a filter is an unresolved challenge. A simple scalable procedure is shown for making a robust, highly compressible 3D crystalline COF nanowire interconnected porous open-cell sponge. The compressive strength and Young's modulus (80% strain) of the sponge are 175 and 238 kPa, respectively. The sponge can withstand multiple compression-release cycles and a load of 2800 times its weight without collapsing. As an exemplary application, the use of a COF sponge in the selective removal and separation of cationic model dye from a mixture of dyes in water by adsorption and filtration with >99% efficiency is shown. Depending on the dye concentration, the dye removal time can be as short as 2 min, and dye adsorption efficiency can be as high as 653 mg g(-1) (COF in the sponge). During filtration, the sponges as filters show a high water flux of 2355 L h(-1) m(-2) under ambient conditions and maintain their performance for many cycles. The lightweight, reusability, and efficiency make present sponges sustainable materials as adsorbents and filters.

Automated summary

A simple and scalable method of making a robust, highly compressible 3D porous sponge made of interconnected crystalline organic frameworks (COF) nanowires is demonstrated. The sponge exhibits high compressive strength and can withstand multiple compression-release cycles and a load of 2800 times its weight without collapsing. As a filter, the sponge shows a high water flux and maintains its performance for many cycles.