3D-Printed Cellulose Nanofiber Aerogel for Water Harvesting

3D-Printed Cellulose Nanofiber Aerogel for Water Harvesting

Author: ChemistryViews

Freshwater scarcity is a problem in many regions of the world and is made worse by population growth and climate change. One sustainable approach to obtaining freshwater is sorption-based atmospheric water harvesting using solar energy. In this method, hygroscopic sorbents are used to capture moisture even from extremely dry environments and the captured water is then released under sunlight. Materials with hygroscopic salts such as LiCl can provide a high water uptake, but can suffer from agglomeration and salt leakage, which reduce performance.

Wenshuai Chen, Ministry of Education Northeast Forestry University, Harbin, China, Gang Chen, Feng Jiang, The University of British Columbia, Vancouver, Canada, and colleagues have developed a 3D-printed, hierarchically structured aerogel scaffold made from cellulose nanofibers (CNFs), carbon nanotubes (CNTs), and lithium chloride for water harvesting. The porous structure confines the LiCl and simultaneously provides a larger active area for water sorption.

The team extracted CNFs from northern bleached softwood kraft pulp via a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and used the nanofibers to prepare a high-viscosity ink for 3D printing. The printed porous structures were then soaked in an LiCl solution and freeze-dried to obtain lightweight scaffolds. To promote water evaporation under sunlight, the scaffolds were coated with a thin layer of black CNF/CNT, which acts as a solar absorber. The team found that the 3D printed scaffold exhibits a water sorption rate that is 1.6 times higher and a water release rate that is 2.4 times higher than those of a conventional freeze-dried aerogel. Thus, the printed porous scaffold could be useful for water harvesting from the atmosphere.


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