Molecular Simulation of High-Salinity Brines in Contact with Diisopropylamine and Tripropylamine Solvents

Abstract

All-atom molecular dynamics simulations are used to understand the structural and thermodynamic behavior of water in a biphasic system composed of a brine solution in contact with two different amine-based solvents, diisopropylamine (DiPA) and tripropylamine. As compared to the bulk brine solution, the biphasic system leads to significant salt aggregation and crystallization, and this behavior is observed over a relatively broad range of temperatures, from 278 to 343 K. In general, there are stronger hydrogen bond interactions between DiPA and water, leading to more favorable solvation and reduced diffusion rates. Detailed analysis of the solvation behavior is provided by using thermodynamic integration to calculate the free energy of water solvation in different brine and solvent mixtures. This also indicates a stronger interaction of water with the DiPA solvent, and this occurs mainly via interactions of the oxygen atoms in water with the nitrogen atoms of the solvent molecules. Overall, the structural and thermodynamic analyses in this study provide a better molecular-level understanding of solvent-based desalination of high-salinity brines.

Molecular Simulations of Understanding Separation of Cadmium and Lead Ions from Aqueous Waste Water Using Directional Solvent Extraction

“…Similar crystallization, thereby uptake of these metal ions nitrates, is observed in the presence of calcite at room temperature previously via uptake experiments by El-Korashy . This behavior is also observed in the previous simulation studies. ,,− However, we observe a clear enhanced density distribution peak with the presence of solvent molecules. This migration of ions in the presence of less polar solvent DEC.…”

“…Various solvents have been utilized for the DSE method, organic fatty acids such as decanoic acid (DEC), octanoic acid, multiple forms of amines, ,,, and ionic solvents such as different forms of imidazolium. , Very limited molecular level simulation studies that exist in the literature to understand the molecular insights of desalination using the DSE method. ,,− Most of the available literature on experiments and molecular simulation studies involves desalinating various brine forms such as NaCl, KCl, KBr, NaBr, etc. However, as per our knowledge, detailed molecular-level investigations of the DSE process for the metal ion separation are lacking.…”

Computational and experimental study of different brines in temperature swing solvent extraction desalination with amine solvents

“…At present, only a few molecular simulation studies have been performed to provide deeper molecular-level insight into the TSSE desalination process [20][21][22][23][24][25]. Furthermore, almost all the experimental work thus far has focused on NaCl as the model brine solution, i.e., other salts besides NaCl have not been thoroughly investigated.…”

Thermodynamics of solvent-driven water extraction from hypersaline brines using dimethyl ether

“…Expressions for the short-and middle-range contributions to the excess Gibbs free energy (Equations 7 and 9, respectively) contain interaction parameters that must be estimated through the regression of experimental data, predicted using group contribution methods [46,48,51,[68][69][70], or calculated from first-principles simulations [71][72][73][74][75][76][77][78][79]. In this work, experimental data from liquid-liquid, vapor-liquid, vapor-liquid-liquid equilibrium (LLE, VLE, and VLLE, respectively) is combined with osmotic coefficient measurements to determine the short-(a (0) ji and a (1) ji in Equation 7) and middle-range interaction parameters (b ij , c ij , b jcja , and c jcja in Equation 9) in the LIQUAC model.…”