Thermodynamic Properties of Aqueous Sodium Chloride Solutions

Pitzer, Kenneth S.; Peiper, J. Christopher; Busey, R. H.

doi:10.1063/1.555709

Cited by 726 publications

(524 citation statements)

References 23 publications

(40 reference statements)

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“…A.19. p vap (T, s) for sodium chloride solution is obtained from Pitzer's model [49]. Over the range of temperatures and feed salinities relevant to MD, ∆T VPD ≈ ∆T BPE with a maximum deviation of about 3%, occurring at high salinity and temperature.…”

Section: Discussionmentioning

confidence: 99%

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Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

et al. 2018

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This study presents a comprehensive analytical framework to design efficient single-stage membrane distillation (MD) systems for the desalination of feed streams up to high salinity. MD performance is quantified in terms of energy efficiency (represented as a gained output ratio, or GOR) and vapor flux, both of which together affect the specific cost of pure water production. Irrespective of the feed salinity, permeate or conductive gap MD (P/CGMD) performs better than direct contact MD (DCMD) when the heat transfer resistance of the gap (in P/CGMD) is lower than that of the external heat exchanger in DCMD. Air gap MD's (AGMD) better performance relative to the other configurations at high salinity and large system area can be explained in terms of its thicker 'effective membrane', which includes the air-gap region. CGMD and DCMD employing a thick membrane are also resilient to high salinity, similar to AGMD, while not being susceptible to the gap flooding that can harm AGMD's performance. A method is described to simultaneously determine the cost-optimal membrane thickness and system size as a function of the ratio of specific costs of heat energy and module area. At low salinity and small system size, GOR rises and flux declines with an increase in membrane area. For salty feed solutions, there exists a critical system size beyond which GOR also begins to decline. Since both GOR and flux are lower, no economic rationale favors operation above this critical size, irrespective of the costs of thermal energy and system area. A closed-form analytical expression for this critical system area is derived as a function of the feed salinity and two dimensionless ratios of heat transfer resistances within the MD module.Keywords: membrane distillation, high salinity, energy efficiency, system size, optimal membrane thickness * Corresponding author: lienhard@mit.

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Section: Discussionmentioning

confidence: 99%

“…Pure sodium chloride solution up to 260 g/kg is considered as the feed. To account for the nonlinear effect of high feed salinity on vapor pressure, Pitzer's equations [49] describing the properties of aqueous NaCl solution were used to evaluate water activity and thereby water vapor pressure on the feed side:…”

Section: Manuscript Overviewmentioning

confidence: 99%

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

et al. 2018

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“…The value of ψ theoretical can be calculated from the thermodynamic activities of the salt solutions. The activity coefficients for 0.1 mol/L NaCl and 0.5 mol/L NaCl were taken as 0.778 51 and 0.686, 9 respectively, and the value of ψ theoretical was calculated to be 38.1 mV. 19 Multiple measurements were averaged, and the uncertainty was taken as one standard deviation from the mean.…”

Section: Intrinsic Ionicmentioning

confidence: 99%

Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

Geise

Hickner

Logan

2013

ACS Appl. Mater. Interfaces

250

239

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Salinity gradient energy technologies, such as reverse electrodialysis (RED) and capacitive mixing based on Donnan potential (Capmix CDP), could help address the global need for noncarbon-based energy. Anion exchange membranes (AEMs) are a key component in these systems, and improved AEMs are needed in order to optimize and extend salinity gradient energy technologies. We measured ionic resistance and permselectivity properties of quaternary ammonium-functionalized AEMs based on poly(sulfone) and poly(phenylene oxide) polymer backbones and developed structure−property relationships between the transport properties and the water content and fixed charge concentration of the membranes. Ion transport and ion exclusion properties depend on the volume fraction of water in the polymer membrane, and the chemical nature of the polymer itself can influence fine-tuning of the transport properties to obtain membranes with other useful properties, such as chemical and dimensional stability. The ionic resistance of the AEMs considered in this study decreased by more than 3 orders of magnitude (i.e., from 3900 to 1.6 Ω m) and the permselectivity decreased by 6% (i.e., from 0.91 to 0.85) as the volume fraction of water in the polymer was varied by a factor of 3.8 (i.e., from 0.1 to 0.38). Water content was used to rationalize a tradeoff relationship between the permselectivity and ionic resistance of these AEMs whereby polymers with higher water content tend to have lower ionic resistance and lower permselectivity. The correlation of ion transport properties with water volume fraction and fixed charge concentration is discussed with emphasis on the importance of considering water volume fraction when interpreting ion transport data.

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“…Properties for aqueous sodium chloride were obtained from an implementation of Pitzer's equations [37]. Parameters used for modeling as well as the results are given in Table 1.…”

Section: Mechanical Vapor Compression Brine Concentrationmentioning

confidence: 99%

“…The activity coefficients were obtained from an implementation by Thiel et al [30,33] of Pitzer's equations modeling the thermodynamics of aqueous electrolyte solutions [34][35][36][37][38][39]. Thiel et al [30] found that aqueous NaCl serves as a reasonable surrogate for the property estimation in certain high salinity waters.…”

Section: Salt Production and Zero-discharge Desalinationmentioning

confidence: 99%

Thermodynamic analysis of brine management methods: Zero-discharge desalination and salinity-gradient power production

et al. 2017

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Growing desalination capacity worldwide has made management of discharge brines an increasingly urgent environmental challenge. An important step in understanding how to choose between different brine management processes is to study the energetics of these processes. In this paper, we analyze two different ways of managing highly saline brines. The first method is complete separation with production of salts (i.e., zero-discharge desalination or ZDD). Thermodynamic limits of the ZDD process were calculated. This result was applied to the state-of-the-art industrial ZDD process to quantify how close these systems are to the thermodynamic limit, and to compare the energy consumption of the brine concentration step to the crystallization step. We conclude that the brine concentration step has more potential for improvement compared to the crystallization step. The second brine management method considered is salinity-gradient power generation through pressure-retarded osmosis (PRO), which utilizes the brine's high concentration to produce useful work while reducing its concentration by mixing the brine with a lower salinity stream in a controlled manner. We model the PRO system coupled with a desalination system using a detailed numerical optimization, which resulted in about 0.42 kWh/m 3 of energy saving.

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Thermodynamic Properties of Aqueous Sodium Chloride Solutions

Cited by 726 publications

References 23 publications

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

Energy efficiency of membrane distillation up to high salinity: Evaluating critical system size and optimal membrane thickness

Ionic Resistance and Permselectivity Tradeoffs in Anion Exchange Membranes

Thermodynamic analysis of brine management methods: Zero-discharge desalination and salinity-gradient power production

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