Comparative efficiency of different polyol-based deep eutectic solvents for chitin extraction from lobster shells

Abstract

In this study, deep eutectic solvent (DES) prepared from choline chloride, lactic acid, and one of the four polyols (ethylene glycol, glycerol, xylitol, and sorbitol) were compared and assessed for their effectiveness in extracting chitin from lobster shells. Our results revealed that as the number of hydroxyl groups in polyols increased, the hydrogen bond network within the DESs became denser. However, this led to a corresponding increase in viscosity, which impacted the efficiency of chitin extraction. Among all prepared DESs, choline chloride-lactic acid/glycerol (CCLaGly) exhibited superior extractive ability, resulting in the extraction of pure chitin from lobster shells. The purity, crystallinity, and molecular weight of the extracted chitin using CCLaGly DES were comparable to those of chemically-isolated chitin, with purity reaching 94.76 ± 0.33 %, crystallinity at 78.78 %, and a molecular weight of 655 kDa. Additionally, the physicochemical properties of the DES-extracted chitins were characterized using Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy. This study conducted a comparative analysis of polyol effects on chitin extraction from lobster shells, thereby opening a promising avenue for the utilization of various crustacean shells in sustainable biomaterial production.