Thermophysical Characterization of Sustainable Pathways for Hydrofluorocarbons Separation Utilizing Deep Eutectic Solvents

The widespread use of hydrofluorocarbons (HFCs) in refrigeration ushered in a significant environmental challenge due to their high global warming potential. Effective recovery and separation techniques are imperative to mitigate their adverse impacts and promote sustainability. This study investigates the solubility behavior of four common HFCs (R-125, R-134a, R-32, and R143a) using choline chloride ([Ch]Cl) and tetramethylammonium chloride (TMAC) based Deep Eutectic Solvents (DESs) as ecofriendly, low-toxicity and low-cost alternatives, provided the promising selectivity exhibited by some of them in separating HFC mixtures. The new experimental data are completed by a comprehensive thermodynamic characterization employing the soft-SAFT equation. This modeling enables the description of the density and viscosity of pure DESs, enthalpy and entropy of dissolution, Henry's constants, and ideal selectivity. From these results, the competitive selectivity among gases in multi-component blends and DESs is predicted. R-32 appears to have the highest affinity in DESs, followed by R-134a, R-143a, and R-125, while TMAC:EG (1:3) shows the highest absorption capacity for all HFCs. Despite relatively low absorption rates, DESs containing TMAC:GL (1:3) and [Ch]Cl:GL (1:3) + 10 wt% exhibit promising selectivity for separating HFCs mixtures, especially those containing R-32, which holds significance for applications in recovering commercial blends like R410A and R407F.