Chitin Extraction at Room Temperature Using a Novel Temperature-Responsive Switchable Deep Eutectic System with Enhanced Recyclability

In this research, a novel temperature-responsive switchable deep eutectic solvent extraction system (TRSDES-H2O) was developed for extracting chitin from crustacean shells. The system, consisting of lidocaine, oleic acid, acetic acid, and water, effectively extracts chitin at room temperature. Additionally, under varying temperatures, this system can rapidly switch between hydrophilicity and hydrophobicity, allowing for repeated use of the solvent. The TRSDES-H2O system exhibited outstanding chitin extraction performance, with demineralization reaching 98.67% and deproteinization achieving 87.35%. Furthermore, even after 3 cycles, the viscosity of the TRSDES-H2O system remained stable, and its demineralization and deproteinization efficiencies reached 98.87% and 83.63%, respectively. The presence of water in the system facilitates extraction by allowing ionization of the acid. After extraction, the extraction system was switched from a hydrophilic state to a hydrophobic state by adjusting the temperature. This enables the separation of hydrophilic impurities such as soluble minerals and proteins from the system, reducing its viscosity and allowing for its reuse in chitin extraction.