Solubility for dilute sulfur dioxide, viscosities, excess properties, and viscous flow thermodynamics of binary system N,N-dimethylformamide + diethylene glycol

In this paper, isothermal gas–liquid equilibrium data were measured for the system SO2 + N2 in N,N-dimethylformamide (DMF) + diethylene glycol (DEG) at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K and p = 122.66 kPa. Based on these data, Henryʹs law constants were obtained by fitting the linear slope of GLE data. The results indicated the solubility of dilute SO2 in the system DMF + DEG increases with increasing DMF concentration. From the GLE data of dilute SO2 in pure DMF and pure DEG, the thermal parameter of dissolving SO2 in pure DMF and pure DEG was obtained. Meanwhile, density, ρ, and viscosities, ν, for the binary mixtures of DMF + DEG were measured over the whole concentration range at T = (298.15, 303.15, 308.15, 313.15, and 318.15) K. From the experimental density and viscosity data, the excess molar volume, VmE, and viscosity deviations, Δν, were calculated and the calculated results were fitted to a Redlich–Kister equation to obtain the coefficients and estimate the standard deviations between the experimental and calculated quantities. The values of VmE and Δν were negative at all experimental temperatures and components. From the kinematic viscosity data, enthalpy of activation for viscous flow (ΔH*), entropy of activation for the viscous flow (ΔS*), and Gibbs free energy of activation for viscous flow (ΔG*) were calculated.