Diffusion Coefficients of Aqueous Solutions of Ammonium and Potassium Orthophosphates at 25°<sup>1</sup>

Hatfield, John D.; Edwards, O. W.; Dunn, R. L.

doi:10.1021/j100880a022

Cited by 21 publications

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“…The δx shift between two time instances is obtained directly by subtracting the fringe shifts at two different times. The obtained average diffusion coefficients are given in Table 1, along with the reported literature values, 29 which used Gouy interferometry, considered to be one of the most precise methods to measure diffusion coefficients. 9.…”

Section: Resultsmentioning

confidence: 99%

Imaging of mass transfer process using artificial fringe deflection

2014

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A noninterferometric technique used to measure the diffusion coefficients of transparent liquid solutions is reported. This technique uses a white light source and a diffusion cell, with an artificially developed fringe pattern of dark and white stripes at its entrance. As the diffusion process takes place in the cell, the light passing through this nonuniform refractive index medium will bend toward the higher refractive index region, which results in a fringe shift. This shift in the fringe pattern at different times is recorded in a personal computer (PC) using a CCD camera for the calculation of diffusion coefficients. The fringe shift is calculated after skeletonization and linear fit of the captured fringe system. The diffusion coefficient of different concentrations of ammonium dihydrogen phosphate was determined using the proposed technique and the measured values lay within 1% of the reported values. Detailed theoretical and experimental analyses with a comparison of other existing results are discussed.Chhaniwal, Narayanamurthy, and Anand: Imaging of mass transfer process using artificial fringe deflection Downloaded From: http://opticalengineering.spiedigitallibrary.org/ on 05/18/2015 Terms of Use: http://spiedl.org/terms

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Section: Resultsmentioning

confidence: 99%

Imaging of mass transfer process using artificial fringe deflection

2014

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“…The traces were made, by first converting the interferograms into binary images, and then using simultaneous vertical and horizontal scans [20]. Table 1 along with diffusion coefficients obtained using other experimental methods (literature values) [12,21,22]. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The error in the obtained diffusivity values was calculated by considering the average of Refs. [21,22] as the right diffusivity value. It can be seen that the error is less than 1% over the whole concentration range.…”

Section: Resultsmentioning

confidence: 99%

Measurement of diffusion coefficient of transparent liquid solutions using Michelson interferometer

Chhaniwal

Anand

Narayanamurthy

2004

Optics and Lasers in Engineering

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“…The solutions were prepared in a jacketed stirred vessel using immersion probes (WTW TetraCon 325 (K = 0.475 cm -1 and Schott LF1101T (K = 0.9 cm -1 )) and throughput cells in a circulation loop (WTW LR325/01 (K = 0.1 cm )) for the required conductivity measurement. [7,8] and measured with a Gouy interferometer [9]. The experimental values were fitted with an Antoine-like expression:…”

Section: Methodsmentioning

confidence: 99%

Surface Specific Mixing Rule for Ionic Diffusion Coefficients at Infinite Dilution in Polymer/Water Mixtures

Machefer

Schnitzlein

2008

Chem Eng & Technol

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It has recently been shown that the viscosity of polymer/water mixtures can be accurately predicted with an ideal linear mixing rule based on molecular van der Waals surfaces. Because of the Stokes-Einstein relation, a similar mixing rule may also be applicable to ionic diffusion coefficients at infinite dilution in polymer/water mixtures. This assumption is confirmed for the example system KDP/polyol/water at various temperatures. Moreover, the impact on electrolyte concentration is calculated and shows that the surface-based mixing rule can also be used as a good approximation for the ionic diffusion coefficient for finite electrolyte concentrations. IntroductionDiffusion of ions through a solution is a complicated process since long-range coulomb forces, electrophoresis and dissociation have to be additionally considered when compared to diffusion of uncharged molecules. Circumstances become highly complicated when the aqueous solution contains organic or, even worse, polymer admixtures which affect dielectricity, viscosity and ion dissociation. However, at infinite dilution, ions can be treated like molecular species. In this case, diffusion of molecules or ions may be treated like macroscopic particles within the framework of the Stokes law and a direct relation to viscosity is given according to the Stokes-Einstein equation [1] 1) :In a recent paper, linear ideal mixing rules for calculating mixture viscosities for binary mixtures containing polyol (index 2) and water (index 1) have been discussed. From Eyrings theory [2] the following mixing rule based on segment fractions n t was derived [3]: lng = lng 1 (1 -n t,2 ) + ln g 2 n t,2Van der Waals (VdW) surface fractions n q have been shown to be a good approximation for the segment fractions n t which can currently only be derived from experiments for complex polymers like polyols [3]. This way, viscosities of several binary mixtures containing different polyols with water could be reliably calculated with this entirely predictive VdW surface-based mixing rule [4]. Eq. (1) is equivalent to:A similar mixing rule may therefore also be applicable to ionic diffusion coefficients at infinite dilution:whereThe VdW molecular surfaces for any kind of organic species can be approximated from functional group contributions published elsewhere [5].This work focuses on an example electrolyte system containing potassium dihydrogen phosphate (KDP), water and a polyol admixture. Diffusion coefficients at infinite dilution are calculated from experimental limiting equivalent conductivities and compared to Eq. (4). The impact of electrolyte content on the ionic diffusion coefficient up to saturation is calculated from a rigorous physical model in order to assess deviations from Eq. (4) for finite electrolyte concentrations. -1) List of symbols at the end of the paper.

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Diffusion Coefficients of Aqueous Solutions of Ammonium and Potassium Orthophosphates at 25°¹

Cited by 21 publications

References 0 publications

Imaging of mass transfer process using artificial fringe deflection

Imaging of mass transfer process using artificial fringe deflection

Measurement of diffusion coefficient of transparent liquid solutions using Michelson interferometer

Surface Specific Mixing Rule for Ionic Diffusion Coefficients at Infinite Dilution in Polymer/Water Mixtures

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Diffusion Coefficients of Aqueous Solutions of Ammonium and Potassium Orthophosphates at 25°1

Cited by 21 publications

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Imaging of mass transfer process using artificial fringe deflection

Imaging of mass transfer process using artificial fringe deflection

Measurement of diffusion coefficient of transparent liquid solutions using Michelson interferometer

Surface Specific Mixing Rule for Ionic Diffusion Coefficients at Infinite Dilution in Polymer/Water Mixtures

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Diffusion Coefficients of Aqueous Solutions of Ammonium and Potassium Orthophosphates at 25°¹