Separation of aromatics from aliphatics is a challenging process because of the close range of their boiling points and the formation of several combinations of azeotropes. Until now, no feasible separation process is available for aromatic concentrations below 20 wt%. In this work, we have investigated the possibility of using a selected deep eutectic solvent (DES) for the liquid–liquid extraction of benzene, toluene, ethylbenzene and m-xylene (BTEX) aromatics. The DES used in this work was synthesized by combining tetrabutylammonium salt and sulfolane. Equilibrium data for the ternary system consisting of BTEX aromatics, n-octane and DES were measured at 25 °C and atmospheric pressure. The results showed that the used DESs have comparable distribution ratios and selectivities to those of commercial solvents. In all tested systems, sulfolane was not present in the hydrocarbon layer. It was also found that the selectivity decreases with decreasing polarity of the aromatic compound. The Non-Random Two Liquid (NRTL) model was successfully used to correlate the experimental tie-lines and to calculate the phase compositions of the ternary systems. In addition, the performance of COSMO-RS to predict the ternary tie-lines for the studied systems was evaluated and the σ-profiles were used to explain the interaction between the DES and the aromatic compounds.

The release of certain gases to the atmosphere is controlled in many countries owing to their negative impact on the environment and human health. These gases include carbon dioxide (CO₂), sulfur oxides (SOx), nitrogen oxides (NOx), hydrogen sulfide (H₂S) and ammonia (NH₃). Considering the major contribution of greenhouse gases to global warming and climate change, mitigation of these gases is one of the world’s primary challenges. Nevertheless, the commercial processes used to capture these gases suffer from several drawbacks, including the use of volatile solvents, generation of hazardous byproducts, and high-energy demand. Research in green chemistry has resulted in the synthesis of potentially green solvents that are non-toxic, efficient, and environmentally friendly. Deep eutectic solvents (DESs) are novel solvents that upon wise choice of their constituents can be green and tunable with high biocompatibility, high degradability, and low cost. Consequently, the capture of toxic gases by DESs is promising and environmentally friendly and has attracted much attention during the last decade. Here, we review recent results on capture of these gases using different types of DESs. The effect of different parameters, such as chemical structure, molar ratio, temperature, and pressure, on capture efficiency is discussed.

Green Deep Eutectic Solvents (DESs) are considered here as an alternative to conventional organic solvents and ionic liquids (IL) for the extraction of phenolic compounds from pyrolysis oil. Although ionic liquids have shown a promising future in extraction processes, DESs possess not only most of their remarkable physico-chemical properties, but are also cheaper, easier to prepare and non-toxic, increasing the infatuation with these new moieties to the detriment of ionic liquids. In this work, phenol was selected as a representative of phenolic compounds, and toluene and heptane were used to model the pyrolysis oil. COSMO-RS was used to investigate the interaction between the considered Dess, phenol, n-heptane, and toluene. Two DESs (one ammonium and one phosphonium based) were subsequently used for experimental liquid–liquid extraction. A ternary liquid–liquid equilibrium (LLE) experiment was conducted with different feed concentrations of phenol ranging from 5 to 25 wt% in model oil at 25 °C and at atmospheric pressure. Although both DESs were able to extract phenol from model pyrolysis oil with high distribution ratios, the results showed that ammonium-based DES was more efficient than the phosphonium-based one. The composition of phenol in the raffinate and extract phases was determined using gas chromatography. A similar trend was observed by the COSMO-RS screening for the two DESs.