Use of Deep Eutectic Solvents and Ionic Liquids for waste biomass valorisation

This PhD research explores the sustainable valorisation of spent coffee grounds (SCG) using Deep Eutectic Solvents (DESs), eco-friendly alternatives to conventional solvents. The study aimed to optimise extraction of valuable compounds and assess the toxicity of DESs and their extracts. Oil was extracted using p-cymene via ultrasound/microwave-assisted methods and compared to Soxhlet hexane extraction, showing improved efficiency and reduced time. Polyphenol extraction with six DESs was optimised under varying conditions and benchmarked against ethanol and methanol. Antioxidant activity was measured (Folin–Ciocalteu, DPPH, FRAP, β-carotene), and HPLC identified key phenolics (e.g., catechin, chlorogenic acid). Cytotoxicity tests on human C20 and Caco-2 cells showed Bet:EG DES had the lowest toxicity and antioxidant benefits. Extract stability was confirmed over three months. Ecotoxicity tests on Palaemon varians indicated low toxicity at most concentrations. QSAR models based on experimental data effectively predicted DES toxicity, offering a reliable, animal-free screening tool.