Fig. 1.

A Schematic diagram of the chitin isolation from crab shells by the NADES. B SEM images of the crab shells, chitin isolated using the acid–alkali, and chitin isolated using the NADES. C Demineralization and deproteinization efficiency at crab shell/NADES ratios of 1:10, 1:20, and 1:30. D Reusability of the NADES. E FT-IR spectra of the crab shells, chitin isolated by acid–alkali, and chitin isolated by the NADES; XRD curves of the crab shells, CaCO₃, chitin isolated by acid–alkali, and chitin isolated by the NADES; TG curves of the crab shells, chitin isolated by acid–alkali, and chitin isolated by the NADES