Limiting Partial Molar Volumes of Tetra-n-alkylammonium Bromides in xDimethylformamide + (1 − x)Water Mixtures at 298.15 K

García-Pañeda, Eugenio; Miguel, Ernestina Muñoz de; Yanes, and Cayetano; Maestre, Alfredo; Hirakawa, Hiromitsu

doi:10.1021/je960330s

Cited by 4 publications

(2 citation statements)

References 9 publications

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“…Apparent molar volumes in DMF for most of the ions and compounds used were extrapolated from information in the literature ͑all values in cm 3 /mol͒: TBAI ͑320͒, TBAI 3 ͑397͒, TPAI ͑250͒, TPAI 3 ͑327͒, I Ϫ ͑40͒, TBA ϩ ͑280͒, and TPA ϩ ͑210͒. [6][7][8][9][10][11] By dissolving I 2 into solutions of TBAI and measuring the resulting change in density, we estimated V ⌽ for I 3 Ϫ to be 117 cm 3 /mol. Using these values and either Eq.…”

Section: Discussionmentioning

confidence: 99%

Electrochemical Pumping of DMF Electrolyte Solutions across Membranes

Norman¹,

Noble

Koval³

2004

J. Electrochem. Soc.

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Electrolysis of ͑dimethylformamide͒ ͑DMF͒ solutions containing tetraalkylammonium iodide salts and dissolved iodine in a two-compartment cell separated by a Nafion membrane results in transfer of solution volume between the two compartments. The pumping process was reversible and the rate, which ranged from 20 to 50 L/min, was controlled by the cell current. The volume of solution pumped was significantly greater than what is predicted from the apparent molar volumes of the species involved in the electrolysis and from the charge passed. The additional volume is attributed to migration-assisted solvent flow across the membrane separator. Comparison of pumping results for a series of Nafion materials indicated that the solvent flow was related to the number of solvent molecules per ion-exchange site in the membrane. Pumping occurred with and against small external pressures up to 0.1 atm. Analysis of apparent molar ionic volumes indicates that the electrode reaction, I 3 Ϫ ϩ 2e Ϫ ϭ 3I Ϫ , contributes little to the observed volume change. Instead, the pumping is associated almost entirely with the apparent molar ionic volume of tetraalkylammonium ions and migration-assisted flow of DMF.

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Section: Discussionmentioning

confidence: 99%

Electrochemical Pumping of DMF Electrolyte Solutions across Membranes

Norman¹,

Noble

Koval³

2004

J. Electrochem. Soc.

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“…To obtain the molar volume quantities required in eq 5 to calculate Δ V calcd, apparent molar volumes of salts involved in the electrolysis experiments were determined from density measurements (Table ) and the equation where M 2 is the molecular weight of the electrolyte, m is its molality, and ρ and ρ o represent the density of solution and solvent, respectively. Densities for the iodide salts were obtained at several concentrations between 0.1 and 1.0 M. The densities for iodide salt solutions varied linearly with concentration, allowing the density of 0.9 M solutions to be calculated.…”

Section: Resultsmentioning

confidence: 99%

Characterization of a Membrane-Based, Electrochemically Driven Pumping System Using Aqueous Electrolyte Solutions

et al. 2005

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Electrokinetic flow provides a mechanism for a variety of fluid pumping schemes. The design and characterization of an electrochemically driven pump that utilizes porous carbon electrodes, iodide/triiodide redox electrolytes, and Nafion membranes is described. Fluid pumping by the cell is reversible and controlled by the cell current. Chronopotentiometry experiments indicate that the total available fluid that can be pumped in a single electrolysis without gas evolution is determined solely by the initial concentration of electrolyte and the applied current. The magnitude of the fluid flow at a given current is determined by the nature of the cation in the electrolyte and by the water absorption properties of the Nafion membrane. For 1 M aqueous electrolytes, pumping rates ranging from 1 to 14 microL/min were obtained for current densities of 10-30 mA/cm2 of membrane area. Molar volume changes for the I3-/I- redox couple and for the alkali cation migration contribute little to the observed volumetric flow rates; the magnitude of the flow is dominated by the migration-induced flow of water.

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