Solubility of Dilute SO₂ in Mixtures of <i>N</i>,<i>N</i>‑Dimethylformamide + Polyethylene Glycol 400 and the Density and Viscosity of the Mixtures

In this work, the isothermal gas–liquid equilibrium (GLE) data were measured for the system of polyethylene glycol 400 (PEG 400) + <i>N</i>,<i>N</i>-dimethylformamide (DMF) + SO₂ + N₂ at 308.15 K and 123 kPa with SO₂ partial pressures in the range of (16.8 to 115) Pa. The Henry’s law constant (<i>H</i>′) and standard Gibbs free energy change (Δ<i>G</i>) were calculated from these GLE data. Furthermore, the densities and viscosities of binary mixtures of DMF + PEG 400 were also measured over the whole concentration range at <i>T</i> = (298.15 to 313.15) K. From the experimental data, including density and viscosity values, the excess molar volumes (<i>V</i>_m^E), and viscosity deviations (Δη), the calculated results are fitted to a Redlich–Kister equation to obtain the coefficients and estimate the standard deviations between the experimental and the calculated quantities

Efficient SO₂ Absorptions by Four Kinds of Deep Eutectic Solvents Based on Choline Chloride

Four kinds of deep eutectic solvents (DESs) based on choline chloride (ChCl) with ethylene glycol (EG), malonic acid (MA), urea, and thiourea as hydrogen bond donors were prepared and characterized. All these DESs show good thermal stability and can be stable at 363 K, which is beneficial for the application in flue gas desulfurization. Then, SO₂ absorption capacities of these DESs were determined at different temperatures and SO₂ partial pressures. The absorption results demonstrate that ChCl–EG (1:2) and ChCl–thiourea (1:1) DESs exhibit excellent absorption performances, and the absorption capacities are 2.88 and 2.96 mol SO₂ per mol DES at 293 K and 1 atm, respectively. In addition, the SO₂ absorption and regeneration experiments were conducted. All solvents can be regenerated at 343 K with N₂ bubbling, and the absorption capacities of DESs remain without a significant loss after six absorption and desorption cycles. What’s more, the absorption mechanism of SO₂ in these DESs were investigated by IR and ¹H NMR

Effect of solvent extraction on the composition of coal tar residues and their pyrolysis characteristics

A large amount of coal tar residues (CTRs) produced in the coal coking or gasification industry has not been effectively utilized in China. In this study, CTRs are extracted by 12 organic solvents. Detailed investigations are carried out via ultimate analysis, Fourier transform infrared spectroscopy (FTIR) and thermogravimetry (TG) analyzer. The pyrolysis process of CTRs and their extraction residues (RCTRs) can be accurately fitted by Coast-Redfern integral model. The results indicate that the reaction order (n), apparent activation energy (Ea) and pre-exponential factor (A) were in the range of 2–7, 34.42–60.08 kJ mol−1 and 102-105 min−1, respectively. Correlations are observed between parameters (H, C, O, H/C, WT, Rmax, n, Ea, and lnA) and the yield of RCTRs, suggesting that the composition and pyrolysis behavior are controlled by the solvent extraction. Specifically, extraction with n-heptane, methanol and ethanol could reduce the Ea and promote CTRs decomposition by disrupting the noncovalent bonds. When extracted with CS2, DMF, benzene, toluene, acetone, etc. the recovery rate of tar and the yield of pyrolysis products are improved, however, the reactivity decrease due to the increase in activation energy.</p