Cleaning contaminants from cotton textiles using compressed liquid CO₂ and co-solvent mixtures

Liquid CO₂ (L-CO₂) has emerged as a safe and sustainable alternative to conventional organic solvents in dry cleaning owing to its non-toxic, non-flammable, and environmentally friendly nature. However, the compounds that can be removed from the fabrics by L-CO₂ are unknown. In this study, we optimized the temperature, flow rate, and co-solvent for L-CO₂ dry cleaning and identified the compounds that can be removed by this method using gas chromatography-time-of-flight mass spectrometry. A 7:3 (v/v) isopropanol(IPA)/water mixture was the optimal co-solvent mixture. Our L-CO₂+IPA/H₂O dry cleaning method exhibited high efficacy in removing a diverse range of substances, such as cholesterols, fatty acids, N-compounds, sugars, and sugar derivatives. In particular, 100% of the cholesterols were removed from the stained fabric.