Recovery of Astaxanthin from Antarctic Krill (Euphausia superba) Waste by Using Thermo-reversible Ionic Liquid-Water Systems: Phase Behavior, Extraction and Residue Utilization

Abstract

Conventional extraction techniques to recover astaxanthin from shrimp waste usually rely on organic solvents. In this study, ionic liquids were used to form thermo-reversible biphasic systems with water, and the systems were applied to extract astaxanthin from antarctic krill waste. The phase diagrams and physicochemical properties of the systems were investigated. Then the extraction conditions were studied to obtain high astaxanthin yield. Moreover, the extraction mechanism was revealed and the storage stability of the extract was evaluated. Furthermore, the extraction residue was used as bio-adsorbent to remove organic dyes to maximize the utilization of shrimp waste. Results show the system formed by tetrabutylphosphonoium trifluoroacetate ([P4444]CF3COO) achieved highest extraction efficiency up to 35.78μg/g under optimal conditions (308.15K, solid-liquid ratio of 1:40, and extraction time of 75min) as compared with pure [P4444]CF3COO and ethanol. Astaxanthin tended to transfer into the IL-rich phase after the two-phase forming due to hydrogen bonding with [P4444]CF3COO. In addition, the shrimp shell residues with spongy and porous surface presented great removal of 92.6% for Congo red and 97.31% for methylene blue. The study provided a novel and efficiency method to recover astaxanthin from shrimp waste, and meanwhile prepared a biosorbent from the extracted residue.