Cellulose Recovery from Tunicates: A Circular Economy Approach for Aquaculture-Waste Management

Cellulose extraction from Clavelina oblonga, a biofouling invasive species of the Adriatic Sea, was investigated. Cellulose extracted from marine organisms has excellent physicochemical properties, making it an innovative biomaterial for various applications. A sustainable cellulose extraction method based on the use of Deep Eutectic Solvents (DESs) is proposed and different parameters affecting the extraction efficiency were tested. DESs offer many advantages such as low cost, low toxicity, chemical inertness with water, ease of preparation, and, for most of them, biodegradability. An acidic DES constituted of chloride (ChCl) and oxalic acid (OxAc) in a 1:1 molar ratio was exploited for the cellulose extraction from dried tunicate powder. Microwave irradiation was also carried out to improve the extraction process and ensure a uniform temperature distribution throughout the system. Washing of the residual cellulose paste with different solvents allowed the removal of bioproducts of the DES treatment process and good performance of cellulose extraction. Potential esterified cellulose was revealed with promising properties for the extracted material, which can be used as an item for various applications. Further studies are needed to increase the purity of the extracted cellulose.