Liquid−Liquid Equilibria for Benzene + Cyclohexane +N,N-Dimethylformamide + Ammonium Thiocyanate

Abstract

Experimental liquidÀliquid equilibrium (LLE) data were measured for benzene þ cyclohexane þ N,N-dimethylformamide (DMF) þ ammonium thiocyanate (NH 4 SCN) at atmospheric pressure and 298.15 K. The experimental data were correlated using the OthmerÀTobias correlation. The selectivity coefficients of DMF þ NH 4 SCN for benzene are 2 to 15 in this work. The results revealed that the selectivity coefficients increased with the decreasing of the concentration of benzene in the raffinate and increased with the increasing of the mass fraction of NH 4 SCN in the DMF þ NH 4 SCN mixture. Considering the high selectivity for benzene, DMF þ NH 4 SCN may be used as a potential extracting solvent for the separation of benzene and cyclohexane.

Liquid–Liquid Equilibria of Benzene + Cyclohexane + N,N-Dimethyl Acetamide + Ammonium Thiocyanate at 298.15 K and Atmospheric Pressure

“…The internal standard method was used with n-butyl alcohol as the internal standard. 24 Because NH 4 SCN cannot be detected by GC, the mass fraction of NH 4 SCN was calculated via the mass conservation law. For the nonvolatility of NH 4 SCN, a block of glass wool was put in the vaporizing chamber to avoid salt pollution to the column.…”

π-Conjugation-directed highly selective adsorption of benzene over cyclohexane

“…The separation of benzene and cyclohexane is one of the most important and difficult processes in the chemical industry as cyclohexane is usually produced by the catalytic hydrogenation of benzene in the benzene/cyclohexane miscible system and the two substances have very close boiling points (benzene, 80.1 C; cyclohexane, 80.7 C), similar molecular volumes, and low relative volatilities. [1][2][3] Generally, conventional distillation is inadequate for the separation of benzene and cyclohexane in practice, while special distillation such as azeotropic and extractive distillation suffers from complexity and high energy requirement. 4 For these reasons, the search for a more viable alternative to conventional separation processes has become crucial in the development of the chemical industry.…”

Liquid–Liquid Equilibrium for Cyclohexane + Benzene + N,N-Dimethylformamide + Potassium Thiocyanate at Temperature 298.15 K and Atmospheric Pressure

“…The volume of the sample injected in the equipment was 1 μL, and the detection was performed by a flame ionization detector with a capillary column (DB-WAX 1227032LTM, 30 m × 0.25 mm × 0.25 μm). The temperature of both the injector and column was 513.15 K. The gas chromatography operating conditions were based on the literature. − The peak analysis and phase composition determination were performed by using an internal standardization method, with benzene as the internal standard. , Samples of both phases were collected and injected in duplicates. The mass fraction standard deviation was determined by the internal standard relative response factor and ranged from 0.01 to 0.03.…”

“…Such interactions between DMF and other substances, together with its small volume, make it a solvent suitable for salts and compounds with high molecular weight . Ethylene glycol was studied as a co-solvent to improve the DMF selectivity, and the association between DMF and thiocyanate salts (KSCN, NaSCN, and NH 4 SCN) is also present in the literature, demonstrating the solvent improvement in terms of selectivity with the additions. − …”