Multicomponent Fickian solution-diffusion model for osmotic transport through membranes

Foo, Zi Hao; Rehman, Danyal; Coombs, Orisa Z.; Deshmukh, Akshay; Lienhard, John H.

doi:10.1016/j.memsci.2021.119819

Cited by 13 publications

(7 citation statements)

References 46 publications

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“…The literature contains copious evidence of ionic coupling in transmembrane transport, ,,,, although prior studies focused largely on simple pore geometries and dual cation solutions. Here, the effects of transport coupling on ionic fluxes were evaluated using multicomponent salt-lake brines, as illustrated in Figure C,D.…”

Section: Resultsmentioning

confidence: 99%

“…28,50 Next, the original ion rejection measurements of the present work were used to calibrate the model parameters of DSPM-DE, allowing us to infer differences in the solute transport between the dual cation and multicomponent brines. Mindful of the assumptions and limitations of DSPM-DE, we restricted its use to brines of low concentrations (10 g L −1 ), avoiding ion-pairing 58,59 and coupled diffusion 60,61 phenomena that occur at higher concentrations. Further, the model was calibrated to 72 ion rejection measurements from three unique brine compositions (see Supp.…”

Section: Membrane Characterization and Model Calibrationmentioning

confidence: 99%

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Lithium Concentration from Salt-Lake Brine by Donnan-Enhanced Nanofiltration

Foo

Rehman

Bouma

et al. 2023

Environ. Sci. Technol.

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Membranes offer a scalable and cost-effective approach to ion separations for lithium recovery. In the case of salt-lake brines, however, the high feed salinity and low pH of the post-treated feed have an uncertain impact on nanofiltration's selectivity. Here, we adopt experimental and computational approaches to analyze the effect of pH and feed salinity and elucidate key selectivity mechanisms. Our data set comprises over 750 original ion rejection measurements, spanning five salinities and two pH levels, collected using brine solutions that model three saltlake compositions. Our results demonstrate that the Li + /Mg 2+ selectivity of polyamide membranes can be enhanced by 13 times with acid-pretreated feed solutions. This selectivity enhancement is attributed to the amplified Donnan potential from the ionization of carboxyl and amino moieties under low solution pH. As feed salinities increase from 10 to 250 g L −1 , the Li + /Mg 2+ selectivity decreases by ∼43%, a consequence of weakening exclusion mechanisms. Further, our analysis accentuates the importance of measuring separation factors using representative solution compositions to replicate the ion-transport behaviors with salt-lake brine. Consequently, our results reveal that predictions of ion rejection and Li + /Mg 2+ separation factors can be improved by up to 80% when feed solutions with the appropriate Cl − /SO 4 2− molar ratios are used.

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Section: Resultsmentioning

confidence: 99%

Section: Membrane Characterization and Model Calibrationmentioning

confidence: 99%

Lithium Concentration from Salt-Lake Brine by Donnan-Enhanced Nanofiltration

Foo

Rehman

Bouma

et al. 2023

Environ. Sci. Technol.

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“…The model incorporates ion and water transport from electromigration and diffusion. The ion transport rate by electromigration is governed by the transport numbers; the transport number is defined as the proportion of current conducted by the ion relative to the total applied current, characterizing the combined effects of ion partitioning and mobility across the IEM. , The ion and water permeability coefficients are analogous to the conventional parameters used in diffusion models and are regressed from multi-ionic diffusion experiments as reported in our prior publications. ,, Concentration polarization effects in the electrolyte streams, as depicted in Figure B, are incorporated based on mass transfer correlations for the spacers adopted in our experiments (eq 11 in Supporting Information). The diffusion coefficients, density, and viscosity of the multi-ionic solutions are calculated from empirical correlations. − The limiting current density of the each ion is calculated to ensure that the experiments are conducted within the ohmic regime (eq 13 in Supporting Information).…”

Section: Materials and Methodsmentioning

confidence: 99%

“…The ion transport rate by electromigration is governed by the transport numbers; the transport number is defined as the proportion of current conducted by the ion relative to the total applied current, characterizing the combined effects of ion partitioning and mobility across the IEM. 55,56 The ion and water permeability coefficients are analogous to the conventional parameters used in diffusion models 57 and are regressed from multi-ionic diffusion experiments as reported in our prior publications. 35,53,58 Concentration polarization effects in the electrolyte streams, as depicted in Figure 2B, are incorporated based on mass transfer correlations for the spacers adopted in our experiments 11 (eq 11 in Supporting Information).…”

Section: Computational Analysismentioning

confidence: 99%

Sustainable Lithium Recovery from Hypersaline Salt-Lakes by Selective Electrodialysis: Transport and Thermodynamics

Foo,

Thomas,

Heath

et al. 2023

Environ. Sci. Technol.

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Evaporative technology for lithium mining from salt-lakes exacerbates freshwater scarcity and wetland destruction, and suffers from protracted production cycles. Electrodialysis (ED) offers an environmentally benign alternative for continuous lithium extraction and is amenable to renewable energy usage. Salt-lake brines, however, are hypersaline multicomponent mixtures, and the impact of the complex brine–membrane interactions remains poorly understood. Here, we quantify the influence of the solution composition, salinity, and acidity on the counterion selectivity and thermodynamic efficiency of electrodialysis, leveraging 1250 original measurements with salt-lake brines that span four feed salinities, three pH levels, and five current densities. Our experiments reveal that commonly used binary cation solutions, which neglect Na+ and K+ transport, may overestimate the Li+/Mg2+ selectivity by 250% and underpredict the specific energy consumption (SEC) by a factor of 54.8. As a result of the hypersaline conditions, exposure to salt-lake brine weakens the efficacy of Donnan exclusion, amplifying Mg2+ leakage. Higher current densities enhance the Donnan potential across the solution-membrane interface and ameliorate the selectivity degradation with hypersaline brines. However, a steep trade-off between counterion selectivity and thermodynamic efficiency governs ED’s performance: a 6.25 times enhancement in Li+/Mg2+ selectivity is accompanied by a 71.6% increase in the SEC. Lastly, our analysis suggests that an industrial-scale ED module can meet existing salt-lake production capacities, while being powered by a photovoltaic farm that utilizes <1% of the salt-flat area.

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“…The long-term environmental effects should be ascertained from life cycle analysis, to identify next-generation solvent candidates that are safer and more environmentally benign. First, the thermodynamics of directional solubility and the fundamental phenomena governing the process require further investigation; in particular, potential adverse effects, arising from transport coupling in multicomponent brines [137] (including organic molecules and inorganic ions other than Na + and Cl − ), on water selectivity remain unquantified. Data on the effect of temperature on the multinary phase equilibria is limited, and mechanistic understanding of the molecular interactions in water-solvent-salt systems is incomplete.…”

Section: Trends In Chemistrymentioning

confidence: 99%