Influence of adsorbed colloid particles on streaming potential

• Autorzy: Adamczyk Z. , Warszyński P. , Zembala M.
• Języki publikacji: EN

Abstrakty

EN

A new theoretical model was developed for describing changes in streaming potential arising for surfaces covered by adsorbed colloid particles. The laminar flow in a channel of a rectangular cross-section, governed by the Navier-Stokes equation, was solved analytically in the form of a series expansion. Then, assuming the thin electrical doublelayer approximation a general expression for streaming potential was derived for channels having arbitrary surface charge. The influence of adsorbed particles on streaming potential was quantitatively determined by considering the perturbation to the macroscopic shearing flow due to a particle attached to the surface. Two effects were considered: (i) the change in the streaming potential due to flow damping in the vicinity of adsorbed par-ticle, and (ii) the change due to charge transport out from the double layer surrounding adsorbed particles. It was found that both effects were proportional to surface coverage of particles ( for not too high coverages) with the proportionali ty constants determined from appropriate surface integrals to be C(i)(O) = -10.21 and 02 = 6.51. These values, valid for thin double-layers, are independent of particle size, channel shape and ionic strength of the electrolyte. These theoretical predictions were confirmed for channels composed of natural mica sheets covered by positively charged latex particles. Particle coverage e was determined directly by optical and electron microscope counting procedure. A quantitative agreement of the theoretical model with experimental results was found for low coverages. Using the low coverage results an interpolating function was proposed which describes well the adsorbed particle effect for the entire range of coverages. Based on this function anew formula was derived for calculating particle coverage from measured changes of streaming potential. This enables one to determine accurately particle surface coverage in situ by following streaming potential changes.

Słowa kluczowe

EN

adsorption; colloid; streaming potential; electrokinetic phenomena

• Wydawca: Centrum Upowszechniania Nauki PAN
• Czasopismo: Bulletin of the Polish Academy of Sciences. Chemistry
• Rocznik: 1999
• Tom: Vol. 47, No. 3
• Strony: 239--258
• Opis fizyczny: Bibliogr. 38 poz.

Twórcy

autor

Adamczyk Z.

autor

Warszyński P.

autor

Zembala M.

• Institute of Catalysis and Surface Chemistry, Polish Academy of Sciences, Niezapominajek 1, 30-239 Cracow, Poland (Instytut Katalizy i Fizykochemii Powierzchni PAN)