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The use of ethanol as a fuel for motor engines has attracted significant attention because of its possible environmental and economic advantages over fossil fuel. However, the energy demand for the ethanol dehydration process significantly impacts its production cost. A new and energy efficient process is developed on the basis of salt extractive distillation, which uses recycled MgCl2 granules as a separating agent. Vapor-liquor-equilibria (VLE) data for the ternary MgCl2 + ethanol + water system, and the three constituent binary systems were measured at 30, 60, 90, and 101.3 kPa. A large enhancement of relative volatility of the ethanol + water system in the presence of MgCl2 is observed throughout the entire ethanol concentration range, which completely broke the azeotrope. The salt effect of MgCl2 is thought to be the result of energetic interactions and the hydration equilibrium reaction of the Mg2+ ion with water molecules. The calculation results by the mixed-solvent electrolyte model embedded in the OLI platform equipped with new model interaction parameters and equilibrium constant (obtained via the regression of experimental VLE data), provided for a satisfactory means of simulating the MgCl2 salt extractive distillation process. Finally, the process was proven feasible at the laboratory-scale resulting in large granules of recovered MgCl2 and a product of 99.5 wt % ethanol. © 2014 American Institute of Chemical Engineers AIChE J, 61: 664-676, 2015 [ABSTRACT FROM AUTHOR]

Thehigh temperature dissolution behavior of diaspore concentratewas measured in concentrated NaOH–NaAl(OH)4solutions.The dissolution rate of Al was greatly found to be enhanced by increasingNaOH concentration and temperature while decreased with addition ofAl(OH)3. The concentration of Si as the main impurity constantlydecreases with reaction time while the Fe is retained at a limitedlevel. The generalized rate law for mineral dissolution and precipitation,proposed by Lasaga (Lasaga, A. C. Kinetic Theory in the EarthScience; Princeton University Press: Princeton, NJ, USA,1998), was applied to model the kinetic behavior of Al on the basisof KSP(diaspore) and the activity coefficientsof related species in the solution. The resulting kinetic model wascapable of predicting the dissolution rate of Al in the Bayer liquor.The apparent activation energy of the dissolution reaction over thetemperature range from 473.2 to 543.2 K was estimated at 83 kJ·mol–1. [ABSTRACT FROM AUTHOR]

The solubility of sodium aluminosilicate (sodalite),a major desilication product (DSP) in the Bayer process, in NaOH andNaOH–NaAl(OH)4solutions was determined and modeledat temperatures from 303.2 to 348.2 K. Sodium aluminosilicate wassynthesized in a batch crystallizer and the effect of temperature,solution concentrations, and aging time was investigated. Solubilitywas found to increase with increasing NaOH concentration while thesolubility sharply decreases with the addition of Al(OH)3, reaches a minimum at about 0.8 mol·L–1,and then increases. A mixed-solvent electrolyte (MSE) model for thesolubility of sodalite was developed with the help of the OLI platformvia regression to obtain the model parameters. In addition, the desilicationkinetics of NaOH–NaAl(OH)4solutions by using sodaliteas seeds was studied experimentally and modeled with the aid of asecond order kinetic model. The activation energy of desilicationover the temperature range 323.2–363.2 K was found to be 92± 14 kJ·mol–1. Under the optimal operationconditions, 80% silica was removed after 2 h. [ABSTRACT FROM AUTHOR]