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1

Influence of adsorbed colloid particles on streaming potential

100%

Adamczyk Z. , Warszyński P. , Zembala M.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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tom Vol. 47, No. 3

239-258

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.

2

The meaning of the piezoelectric and streaming potential in bone remodeling

63%

Lech Ł. , Iwaniec M.

Vibrations in Physical Systems

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2010

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tom Vol. 24

251--258

EN

In this paper authors include the most important information about piezoelectric effect and streaming potential occurring in bone. In their opinion these phenomena play important role during bone remodeling, so that model binding them together was proposed. Model describes mechanisms responsible for “sensing” by osteocyteslocal changes in stresses and strains and for signal transmissions from sensors to effectors i.e. osteoblasts.

PL

W pracy tej zawarto najważniejsze informacje dotyczące występowania efektu piezoelektrycznego oraz potencjału przepływu w strukturach kostnych, które zdaniem autorów tego tekstu, ma odgrywa ważną rolę przy przebudowie tkanki kostnej. Dlatego został zaproponowany model odbierania sygnałów o stanie mechanicznym kości przez osteocyty i powiązany z modelem oddziaływań międzykomórkowych opisującym przekazywanie informacji z osteocytów do osteoblastów.

3

The use of electrokinetic measurements in a study of pulp wastewater treatment with aluminum and iron (III) salts

63%

Dziejowski J. , Libecki B. , Smoczyński L.

Polish Journal of Chemical Technology

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2005

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tom Vol. 7, nr 1

13-19

EN

Pulp wastewater poses a serious threat to the natural environment. It is characterized by strong coloration and a high content of organic contaminants, including compounds resistant to biochemical decomposition, often toxic to living organisms. Among a variety of physical and chemical methods of wastewater treatment, coagulation is distinguished by its simplicity and efficiency. The effectiveness of the process depends on the pH and the coagulant dose. The optimization of the process parameters can be done based on electrokinetic measurements, including: potential zeta and the streaming potential. This study examined the process of the coagulation of raw effluents from a sulfate pulp mill with aluminum and iron (III) chlorides. A standard jar test method was used. The color, turbidity, suspension and COD were determined in the samples. Tests with and without pH adjustment were conducted. Electrokinetic measurements were performed with a PCD 03 meter (Mütek Analytic Gmbh). It was found that coagulation effectiveness depended on the salts used. A correlation was also observed between the optimum pH for a determined coagulant dose and the reagent-adding sequence. Iron (III) chloride appeared more effective than aluminum chloride as regards the COD elimination. However, taking the lower optimal dose and a higher pH of coagulation into account, aluminum chloride seems to be a better coagulant for pulp wastewater treatment. The increase in the streaming potential recorded during the tests is correlated with the changes in the wastewater pH. The charge of colloids is dependent upon the pH, so different mechanisms of coagulation can be expected.

4

Streaming potential – characteristics of dyed cotton fibres

63%

Pielesz A.

Fibres & Textiles in Eastern Europe

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2010

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tom Vol. 18, no. 2 (79)

103--106

EN

This paper deals with the surface properties of dyed cotton fibres, which were analysed by measuring the streaming potential. Diversified values of the potential were obtained for samples of fabrics dyed with model direct dyes 1-10. Changes in the streaming potential in water solutions of the model dyes were also analysed in order to determine the impact of polar functional groups of the dyes on their anion character. For a broader view of the phenomenon discussed, the analysis of the surface properties of fibres was supplemented with a description of the relative dye content in the fibre, using the K/S ratio.

PL

W niniejszej pracy charakteryzowano powierzchniowe właściwości barwionych włókien bawełny dokonując pomiarów potencjału przepływu. Uzyskano zróżnicowane wartości potencjału przepływu dla próbek tkanin bawełnianych wybarwionych modelowymi barwnikami bezpośrednimi 1-10. Analizowano także zmiany wartości potencjału przepływu w wodnych roztworach modelowych barwników w celu określenia wpływu polarnych grup funkcyjnych barwników na ich anionowy charakter. Dla poszerzenia omawianego zjawiska, poza właściwości powierzchniowe włókien, charakteryzowano także względna zawartość barwników we włóknach, wykorzystując wartości współczynnika K/S.