Solubility of Xylene Isomers in Seven Deep Eutectic Solvents

Abstract

Emissions of volatile organic compounds (VOCs) have a substantial impact on the environment, and absorption methods are an important means of dealing with VOCs. In order to screen potential deep eutectic solvents (DESs) as liquid absorbers for capturing xylenes, seven DESs were prepared and were verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The melting points of all DESs were well below the melting points of their raw materials, and the water content of all the DESs was less than 0.05 wt %. The viscosities of the seven DESs decreased with increasing temperature. The solubility of o-, m-, and p-xylene in the DESs was determined by the cloud point in the range of 303.15−353.15 K. The tetrabutylammonium bromide-based DESs had the greatest potential to dissolve xylene. Tetrabutylammonium bromide:triethylene glycol (1:4) exhibited the highest solubility for o-, m-, and p-xylene, with the mole fraction solubilities of 0.4075, 0.3754, and 0.3820, respectively (each at 353.15 K). The solubility magnitudes of the three isomers exhibited an overall trend of o-xylene > p-xylene ∼ m-xylene. The experimental solubility data were fitted with the dual-parameter equation and the Apelblat equation; the latter was a better fit.