Enhancing sustainable green chemistry using low‐transition‐temperature mixtures with deep eutectic solvents and ionic liquids for eco applications

The environmental impact of conventional chemical processes has driven the search for greener alternatives to volatile organic solvents, which are often toxic and energy intensive. Low‐transition‐temperature mixtures (LTTMs) based on deep eutectic solvents (DESs) and ionic liquids (ILs) offer promising eco‐friendly replacements. This study focuses on the synthesis and evaluation of LTTMs for sustainable green chemistry applications, with emphasis on metal extraction and biomass solubilization. DESs and ILs were prepared by combining hydrogen bond donors and acceptors at specific molar ratios to form homogeneous liquids. Physicochemical properties were assessed through viscosity (25–40°C), conductivity, thermal stability (TGA, DSC), and FTIR spectroscopy to confirm hydrogen bonding. Eco‐compatibility was evaluated using biodegradability and toxicity tests. Application performance was examined through metal ion extraction and biomass processing, with recyclability assessed over three cycles. Results show that DES‐based LTTMs exhibit higher viscosity than ILs, with choline chloride (ChCl)–glycerol and ChCl–urea ranging from 180 to 250 mPa·s, compared to BMIM–Cl (55–60 mPa·s). DES melting points (−40°C to 20°C) were significantly lower than those of ILs (0–100°C). Cu 2+ extraction efficiencies reached 92–95%, with 85–90% solvent recyclability. DESs demonstrated adequate thermal stability (140–320°C) and low environmental impact (0.12–0.18 kg CO 2 eq.). Overall, DES‐based LTTMs show strong potential as sustainable solvent systems. Future work should address scale‐up, viscosity reduction for continuous processing, molecular optimization, and comprehensive life‐cycle assessments to enable industrial implementation.