No abstract

The salting-out effect of NaCl and KCl on the liquid–liquid equilibrium (LLE) of the ternary system of {water (1) + 2-methylpropanoic acid (2) + (1-methylethyl)-benzene (3)}, a recommended system for liquid–liquid extraction investigations, was studied at temperatures of (288.15, 298.15, and 313.15) K. The generated data for salt-free system have been used to estimate the binary molecular interaction parameters for the nonrandom two-liquid (NRTL) activity coefficient model. Results show that this model reproduces very good tie lines by estimated binary molecular interaction coefficients. The distribution coefficient of 2-methylpropanoic acid between organic/aqueous phases increases with its concentration, both in salt-free and in the presence of salt cases; however, it decreases moderately with temperature, within the range used. Adding a 0.05 mass fraction (based on mass of initial water) NaCl leads to an average enhancement of about 4 4% in distribution coefficient, and hence, it reaches to about 124 % by adding 0.10 mass fraction of this salt. The appropriate enhancement achievement with KCl are about (38 and 121) %, respectively. The Othmer–Tobias equation was used to examine the reliability of the experimental results, and an excellent agreement was revealed.

No abstract

The effect of temperature on the liquid–liquid equilibrium (LLE) of the ternary system of {water (1) + acetic acid (2) + 4-methylpentan-2-one (3)}, a recommended system for liquid–liquid extraction studies, was investigated at (288.2, 313.2, and 333.2) K. The reliability of the experimental tie line data was examined with the Othmer–Tobias and the Hand correlations that represented an excellent agreement. The distribution coefficient of acetic acid between organic and aqueous phases increases significantly with temperature, more than 18 % with low solute concentrations, and its value exceeds 1. Meanwhile, a high separation factor within 3.27 to 43.50 was revealed to extract acetic acid from aqueous phase at different temperatures. Higher separations are relevant for low concentrations of acetic acid at 313.2 K. In addition, the binary molecular interaction parameters for the nonrandom two-liquid (NRTL) and the universal quasichemical (UNIQUAC) models were estimated from the experimental results. Results show that these models with their obtained parameters predict tie lines with root-mean square deviation values of 0.0052 and 0.0245, respectively.

a b s t r a c tThe influence of naturally occurring monovalent NaCl and divalent Na 2 SO 4 salts with anions at near extremes of Hafmester series on liquid-liquid equilibrium (LLE) of the chemical system of {water + acetone + 1-Hexyl-3-methylimidazolium hexafluorophosphate (HMIMPF 6 ) ionic liquid} was studied. The conditions were 298.2 K, atmospheric pressure of 81.5 kPa and salts mass fractions in initial aqueous solutions of 0.05 and 0.10. Results show that salting-out effect was significant, so that enhancements in the acetone distribution coefficient was achieved within (21.67-35.54)% for NaCl and (51.84-92.37)% for Na 2 SO 4 . The stronger anion activity and the lack of anion exchange with the used ionic liquid can be the reasons for the stronger effect of the latter salt. The consistency of the experimental data were examined with the improved Eisen-Joffe equation. For modeling purpose, the NRTL and UNIQUAC equations were satisfactorily applied to correlate the phase equilibria. In the presence of NaCl and Na 2 SO 4 salts, the root mean square deviations of compositions, for NRTL equation were 0.0346 and 0.0634 and for UNIQUAC equation 0.1093 and 0.0328, respectively.

No abstract

No abstract

The sphericity and size of ammonium perchlorate (AP) particles significantly influence the properties of composite propellants. As the AP particles become more spherical, the accumulation coefficient increases, the viscosity during casting decreases, and the particle loading and burning rate increase. Hence, the production of micronized AP particles with an average size between 1 and 20 μm is important to increase the loading percentage of AP in the composite propellant. Here, the Taguchi experimental design was used to optimize the solvent-antisolvent crystallization (SAC) process for the preparation of micronized AP particles with higher sphericity. SAC parameters such as the type of antisolvent, the solvent-to-antisolvent ratio, the antisolvent temperature, the stirring speed, and the retention time were investigated at four levels. The type of antisolvent and the solvent-to-antisolvent ratio were found to mainly contribute to improving the sphericity and size of the AP particles, respectively.