The effects of aggregation, counterion binding, and added NaCl on diffusion of aqueous methylene blue

Abstract

DEREK G. LEAIST. Can. J. Chem. 66, 2452Chem. 66, (1988. A simplified version of the Harned conductimetric technique is used to measure binary diffusion of the self-associating dye methylene blue chloride in water at 25°C. As the dye concentration is increased from 0.0006 to 0.02 rnol dm-3, aggregation of the dye monomers and binding of the chloride counterions cause the dye's binary diffusion coefficient to drop from 0.83 x lo-' to 0.63 x lo-' m2 s-'. Ternary diffusion coefficients for aqueous methylene blue chloride + NaCl solutions are also reported.These results show that small amounts of added NaCl (0.005 or 0.01 mol dm-3) sharply reduce the diffusivity of the dye component, and that each mole of diffusing dye cotransports 0.2-0.7 mol NaC1. Diffusion of trace amounts of the dye in the presence of a large excess of an inert supporting electrolyte is discussed briefly. DEREK G. LEAIST. Can. J. Chem. 66, 2452Chem. 66, (1988. On a utilisC une version simplifiee de la technique de conductimetrie de Harned pour mesurer la diffusion binaire du colorant auto-associC, le chlorure du bleu de mtthyltne dans l'eau a 25°C. Lorsque la concentration du colorant passe progressivement de 0,0006 ?A 0,02 mol dm-3, I'aggrtgation des monomtres du colorant et la fixation des ions contraires du chlorure provoquent une chute du coefficient de diffusion binaire du colorant de 0,83 x lop9 a0,63 X lo-' m2 s-I. On rapportetgalement les coefficients de diffusion ternaire des solutions aqueuses de chlorure de bleu de mtthylene + NaCI. Ces rCsultats indiquent que l'addition de petites quantites de NaCl (0,005 ou 0,01 mol dm-3) rtduisent sensiblement la diffusibilite du colorant, et que la diffusion de chaque mole de colorant entraine celle de 0,2 a 0,7 mole de NaCI. On discute brievement de la diffusion du colorant 1'Ctat de traces en presence d'un grand excts d'un electrolyte agissant comme support inerte.[Traduit par la revue]

Optical methods to investigate the enhancement factor of an oxygen‐sensitive colorimetric reaction using microreactors

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Kinetic Study of Leuco‐Indigo Carmine Oxidation and Investigation of Taylor and Dean Flow Superposition in a Coiled Flow Inverter

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Photoresponsive Passive Micromixers Based on Spiropyran Size‐Tunable Hydrogels

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