Chitin nanocrystals scaffold by directional freezing for high-efficiency water purification

Abstract

Rapid and energy-saving water purification is urgently needed to solve the increasingly severe water shortage problem. Herein, we prepared chitin nanocrystals (ChNCs) scaffolds with aligned channels by the liquid nitrogen-assisted directional freezing method. The aligned channel in the porous ChNCs scaffold can quickly adsorb water to a saturation state. Glutaraldehyde crosslinked ChNCs scaffold (XChNCs) had good mechanical and water stability, which could float on the water surface stably. The ink coated XChNCs scaffold achieved a high evaporation rate of 4.45 kg m-2 h−1 under 1 sun irradiation. Moreover, XChNCs scaffold showed excellent salt, acid, and alkali resistance in the oil–water separation experiment. The XChNCs scaffold showed excellent dye adsorption performance because of its high porosity, and the adsorption ratio of both methylene blue and Congo red dyes exceeded 95 %. This work prepared a renewable, biodegradable, high-performance scaffold derived from biomass, which shows promising application in water purification such as seawater desalination, oil–water separation, and dye adsorption.