Self-diffusion In Water Research Articles

Self-diffusion and polydispersity in water + AOT +p-xylene microemulsions. A dynamic light-scattering study

Download options Please wait... Article information DOI https://doi.org/10.1039/F19858101173 Article type Paper Download Citation J. Chem. Soc., Faraday Trans. 1, 1985,81, 1173-1182 BibTex EndNote MEDLINE ProCite ReferenceManager RefWorks RIS Permissions Request permissions Self-diffusion and polydispersity in water + AOT +p-xylene microemulsions. A dynamic light-scattering study J. H. R. Clarke, J. D. Nicholson and K. N. Regan, J. Chem. Soc., Faraday Trans. 1, 1985, 81, 1173 DOI: 10.1039/F19858101173 To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page. If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given. If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page. Read more about how to correctly acknowledge RSC content. Search articles by author Julian H. R. Clarke J. David Nicholson Karen N. Regan

Self Diffusion in Liquid Water. A Reassessment

Results on tracer and self-diffusion coefficients D of the various isotopic species of water as reported in the literature vary widely. The experimental situation is briefly described and an estimate is made of the best values at 298.15 K and atmospheric pressure. The conclusions are used to judge the results of work on the temperature and pressure dependence of D. A brief account on isotopic effects on tracer and self diffusion in water is given.

Self-diffusion in compressed supercritical water

The self-diffusion coefficients D of compressed supercritical water have been measured as a function of pressure in the temperature range 400 to 700 °C using the NMR spin–echo technique. The experimental diffusion data were compared to theoretical predictions based on a dilute polar gas model using a Stockmayer potential for the evaluation of collision integrals and a temperature dependent hard sphere diameter. The empirical expression ρDαTn, where n = 0.76, fits the experimental data to within±10% over the entire density and temperature region studied. The value of the exponent n = 0.76 agrees favorably with the n values found for diffusion of other gases. The product ρD is density independent under isothermal conditions which indicates that two-body collisions dominate the diffusion behavior. This finding is in agreement with our earlier results for proton relaxation in compressed supercritical water which were analyzed using a binary collision approximation and a collision modulated spin–rotation interaction described by a single correlation function which is an exponential function of time. The hydrodynanic Stokes–Einstein equation appears to hold at densities above ρc. As expected, the diffusion data cannot be described in terms of a hard sphere model but an empirical fit to lnρD = (A/T)+B, where A and B are constants, represents the experimental data well over the range of temperatures and densities studied.

Single-particle motions in liquid water. II. The hydrodynamic model

A compilation is made of available data on the self-diffusion coefficient, the dielectric relaxation time, and the NMR orientational time constant for liquid water under 1 atm pressure at temperatures between 273 and 333 K. The data then are examined in a self-consistent manner for their adherence to a simple hydrodynamic model of single-particle motions. In this model, a water molecule is treated as a rigid sphere with the van der Waals radius which carries out diffusive translations and rotations while surrounded by a viscous continuum. Arbitrary boundary conditions on the velocity field in the surrounding liquid are permitted at the sphere–liquid interface. It is found that the measured coefficient of self-diffusion in liquid water is in quantitative agreement with the predictions of the hydrodynamic model under near-slip boundary conditions, whereas the experimental values of the two orientational time constants are described well by the model under stick boundary conditions. Physical arguments are presented to show why the hydrodynamic model should account accurately for single-particle motions in liquid water at low pressures and temperatures.

Isotope effects and correlated motion in self and sodium ion diffusion in water

The information gained on atomic motions in solids from studies of the isotope effect in diffusion1,2 prompted us to examine this effect in liquids, in particular for diffusion in water, because of its importance as a solvent. As isotope effect measurements for self-diffusion in water and deuterium oxide are available3, the isotope effect for 22Na and 24Na ions in water was studied. We describe here a new technique which applies to liquids the solid state technique of simultaneous diffusion4 of these isotopes followed by sectioning and half-life (or other suitable method) separation.

Pressure and temperature dependence of self-diffusion in water

The self-diffusion coefficient, D, for pure liquid water has been measured at temperatures between 275.2 and 498.2 K and at pressures up to 1.75 kbar by the proton spin echo method. Our values of D agree, where they overlap, with recently published data which, however, were measured mostly at low temperature and over rather narrow ranges of temperature.The results are discussed in several ways. The Stokes–Einstein relation is found to be obeyed in the slipping boundary limit. The cubic cell model of Houghton accounts satisfactorily for the measured D values, particularly at higher temperatures. A simple test of a hard-sphere model is found to give poor agreement at lower temperatures but a modified hard-sphere theory seems to be more satisfactory. The activation analysis at constant density shows that water behaves very differently from non-associated liquids. It also suggests that an increase in both temperature and pressure leads to an increase in the fraction of free unbonded water molecules.A free-volume analysis has led to a modified Arrhenius equation which involves pressure-dependent terms. This semi-empirical equation describes the results within experimental error and predicts a glass temperature at 115 K which is in reasonable agreement with the values obtained by other methods.

Self-diffusion in liquid water

The behavior of the self-diffusion coefficient in water, along the coexistence curve for −31 °C⩽T⩽350 °C, is explained in terms of local fluctuations of free volume, energy per molecule, and ’’percentage of broken H bond’’ as derived from ir data. Our theoretical expression agrees with the experimental data, within their errors, in the overall range we considered. The transition to amorphous state is derived.

Self-diffusion in water and monohydric alcohols

Self-diffusion coefficients for methanol, ethanol, n-propanol, i-propanol and water have been measured as a function of temperature in the range 25–65°C. A flow technique has been used for the first time in the determinations, and the diffusion process has been monitored with the aid of monodeuterated tracers. The self-diffusion coefficients reported for methanol and water are in good agreement with the best available data obtained using n.m.r. techniques. The results have been used to examine both the Eyring theory of liquid diffusion and the more recent correlation of Ertl and Dullien.

Self-diffusion in compressed liquid heavy water

The self-diffusion coefficients D in liquid heavy water have been measured by the NMR spin-echo method over the temperature range 10–200°C and the pressure range 1 bar to 9 kbar. A good agreement with tracer diffusion studies by Woolf performed over a more limited range of temperatures and pressures has been obtained. As in other studies, we find an anomalous initial increase in the diffusion coefficients with pressure at temperatures below approximately 30°C. At high temperatures compression leads to a monotonic decrease of the self-diffusion. The fact that the activation energies at constant density decrease both with increasing temperature and increasing density indicates that both high temperature and high compression significantly affect the hydrogen bond network and produce a more ’’normal’’ liquid. We find that the Stokes–Einstein equation is accurate to within 10% over the range of experimental conditions studied. Phenomenological interpretation of plots of D/T vs molar volume supports the view that at high compression and high temperature the dynamic behavior of heavy water resembles that of a hard sphere liquid. All experimental results are in agreement with our conclusions obtained in our earlier study of NMR relaxation in compressed liquid water and heavy water.

Temperature and pressure dependence of self-diffusion, viscosity and nuclear relaxation times in liquid water

A scaled particle-quansilattice model for liquid water, which is based on the ice VII and ice fc structures, is shown to be capable of explaining several anomalous properties of water. The non-Arrhenius temperature dependence of coefficients of self-diffusion and viscosity and nuclear relaxation times are quantitatively interpreted. Negative volumes of activation, which are observed for viscosity and nuclear relaxation, are also computed to be in good agreement with experiment.

Self-diffusion in normal and heavy water in the range 1-45.deg.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSelf-diffusion in normal and heavy water in the range 1-45.deg.R. MillsCite this: J. Phys. Chem. 1973, 77, 5, 685–688Publication Date (Print):March 1, 1973Publication History Published online1 May 2002Published inissue 1 March 1973https://doi.org/10.1021/j100624a025RIGHTS & PERMISSIONSArticle Views5052Altmetric-Citations1355LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (570 KB) Get e-Alerts

Mechanism of self-diffusion in water

Mechanism of self-diffusion in water

Self-Diffusion in Water

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