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

Abstract

Solvent-driven water extraction (SDWE) has promising applications in hypersaline brine desalination, including zero-liquid discharge processing for industrial wastewaters, and resource recovery, such as the extraction of lithium and rare earth elements from solution mining leachates. In this study, we develop a computational thermodynamic framework to analyze the liquid-liquid extraction of water from hypersaline brines using dimethyl ether (DME),

Solvent-driven aqueous separations for hypersaline brine concentration and resource recovery

“…In the extraction step, the thermo-responsive solvent contacts a brine at a favorable temperature for water extraction, functioning as a liquid desiccant. At thermodynamic equilibrium, the two liquids (i.e., aqueous brine and organic solvent) are not fully miscible and form bilayered liquid phases [21,35,52]. After the water-laden organic solvent is physically separated from the raffinate (in this case, a concentrated brine), an induced temperature change decreases the solubility of water in the organic solvent phase.…”

“…To date, a wide range of solvents demonstrating temperature-dependent solubility of water have been investigated for solvent-driven desalination, including alcohols [47,48], aliphatic acids [31,50], amines [35,51], epoxide-based polymers [30], ethers [23,52], and ionic liquids [22,33,34]. These organic solvents possess hydrophilic moieties that form hydrogen bonds and other polar interactions between the extracting solvent and water molecules, allowing for selective solvation of water from the brine.…”

Solvent-driven fractional crystallization for atom-efficient separation of metal salts from permanent magnet leachates

“…Many transition metal and lanthanide salts have relatively high mass fraction solubilities (>25 wt%) but rather low molar solubilities (<2.5 molal), making them an interesting target for solvent-driven FC with the potential for high recoveries. Based on these findings, we have deployed solvent-driven FC to separate transition metal and lanthanide salts using dimethyl ether (DME), a low molecular mass non-coordinating solvent that can be easily recovered 65 – 68 .…”

1-Propyl-4(5)-Methylimidazole Isomers for Temperature Swing Solvent Extraction

“…Other solvent types, such as dimethyl ether (DME) [ 24 , 25 ] and ionic liquids (ILs) [ 19 , 26 ], have been recently investigated for their potential in TSSE. A computational thermodynamic framework was used to estimate that DME could achieve 51 mol% water recovery in a 1-stage process and 63 mol% in 2-stages [ 25 ]. The advantage of DME is a very high volatility which enables its rapid separation from water after water absorption [ 25 ].…”

“…A computational thermodynamic framework was used to estimate that DME could achieve 51 mol% water recovery in a 1-stage process and 63 mol% in 2-stages [ 25 ]. The advantage of DME is a very high volatility which enables its rapid separation from water after water absorption [ 25 ]. The common IL [C 2 mim][Tf 2 N] was found to have a much (~10×) higher water yield than decanoic acid, very low amounts of IL in the product water (<4 ppm), and high product water purity (97.5% NaCl rejection) [ 26 ], however the cost of ILs remains high (~$1000/kg) [ 19 ].…”