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1

Nanostructure of the soluble sodium silicate in the aspect of basic mechanical characteristic of the moulding sands

Baliński A.

ECONTECHMOD : An International Quarterly Journal on Economics of Technology and Modelling Processes

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2012

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Vol. 1, No 1

3-8

EN

The paper describes the consequential advantages of the use of inorganic binders, particularly soluble sodium silicate, in the aspect of the environmental protection. Nanostructure of the soluble sodium silicate as a silicate colloid is described. Research of the structure of the soluble sodium silicate is executed with the use of the PCS method (Photon Correlation Spectroscopy). Characteristic parameters of the nanostructure of the soluble sodium silicate and the method of the estimation of the quantitative structure of the colloid are introduced. It has been proved that the nanostructure of the soluble sodium silicate has an essential influence on its proprieties as binders of the moulding sands. Mechanical characteristic of the moulding sands executed with this binder are dependent on the kind of the nanostructural characteristic of the soluble sodium silicate.

2

Interfacial material constants for system of fine sizes

Grodzka J., Drzymała J., Pomianowski A.

Physicochemical Problems of Mineral Processing

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2008

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Vol. 42

237-250

EN

The properties of bulk and interfacial regions was presented in the paper taking onto account suspensions, colloids, micellar solutions, microemulsions and the so called soft matter, which understanding is as important as the inorganic matter. A special attention was paid to the role and diversity of material constants necessary for delineation of the state and properties of the considered systems.

PL

W pracy szeroko scharakteryzowano właściwości materii i obszarów granicznych pomiędzy elementami materii o różnym rozdrobnieniu biorąc pod uwagę zawiesiny, koloidy, roztwory micelarne, mikroemulsje oraz tzw. materię miękką, której znajomość jest tak samo waża jak materii nieożywionej. Szczególną uwagę zwrócono na rolę i różnorodność stałych materiałowych niezbędnych do opis stanu i właściwości rozpatrywanych przykładów.

3

Phenomenon of vortex rings in method of production nanosuspension metallic

Laskowski S.

Prace Naukowe Instytutu Podstaw Elektrotechniki i Elektrotechnologii Politechniki Wrocławskiej. Konferencje

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2003

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Vol. 39, nr 14

74-80

EN

Nanosuspension was made using wire explosion in the liquid. Providing that silver and copper proportions are right, the liquid could be strongly sterile. Suspension which contains only silver particles has also antibacterial properties. We can control dimensions of metal in water by varying voltage, current and capacity of pulse generator. The experiments let us conclude that the increase of energy (over define limits) does not lead to crumbling in the suspension. It has been confirmed by microscope observations and sedimentation test in different conditions. Different types of wire dezintegration process have been observed and documented thanks to a high speed digital video camera and still photography. It was also possible to notice vortex ring process.

4

Irreversible adsorption of colloids and proteins at heterogeneous surfaces

Adamczyk Z., Weroński P., Musiał E.

Bulletin of the Polish Academy of Sciences. Chemistry

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2002

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Vol. 50, No. 2

175-187

EN

Irreversible adsorption of colloid particles at heterogeneous surfaces was studied theoretically. In contrast to previous models, the dimension of the adsorption sites having the shape of circular discs, was comparable with the size of adsorbing spheres. Adsorption was assumed to occur if the sphere contacted the disc only. Numerical simulation of the Monte-Carlo type enabled one to determine particle flux, adsorption kinetics and jamming coverage as a function of the site density (coverage) and the size ratio particle/site, denoted by lambda . It was demonstrated that adsorption kinetics and the jamming coverage increased significantly, at a fixed site density, when lambda increased, i.e., for larger particle to site size ratio. It was also proven that the results derived from previous model elaborated for negligible site dimensions are valid only if lambda > 10.

5

Colloid adsorption at heterogeneous surfaces

Adamczyk Z., Siwek B., Jachimska B., Kowal A.

Bulletin of the Polish Academy of Sciences. Chemistry

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2002

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Vol. 50, No. 3

347-357

EN

Irreversible adsorption of colloid particles at heterogeneous surfaces was studied experimentally. The substrate of controlled heterogeneity was produced by covering mica sheets by colloid iron oxide (hematite) particles to a desired concentration. The particles of averaged diameter of 70 nm were produced by forced hydrolysis of FeCls solutions followed by a hydrothermal ageing. The coverage of colloid hematite particles (heterogeneity degree) was determined by electron microscopy and atomic force microscopy (AFM). Adsorption kinetics of polystyrene latex (averaged diameter 0.87Mim) at heterogeneous surfaces was studied by using the direct optical microscope observations in the impinging-jet cell. It was demonstrated that the initial adsorption rate attained the limiting value pertinent to homogeneous surfaces for heterogeneity degree of a few per cent. This behaviour was quantitatively interpreted in terms of the theoretical model considering the coupling between surface and bulk transport of particles. Similarly, the experimental results obtained for higher surface coverage of latex (long adsorption times) were in a good agreement with the random sequential adsorption (RSA) model.

6

Colloid silica viscosity determined by the particle sedimentation method

Adamczyk Z., Siwek B., Zembala M.

Bulletin of the Polish Academy of Sciences. Chemistry

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2000

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Vol. 48, No. 3

231-242

EN

Viscosity of colloid silica was determined as a function of the volume fraction varied between 0 and 0.37. A new method of viscosity measurements was applied, based on determination of particle sedimentation velocity. The sedimentation velocity was calcu-lated from the kinetics of irreversible adsorption (deposition) of melamine latex particles (particle size 1.7 and 3.6 pirn) at silanized mica. Deposition kinetics was determined in the sedimentation cell using the direct microscope observation technique. This method is significantly more accurate, especially in the region of low shear rates, than the classical viscosity measurements exploiting commercial viscometers. It was found that colloid silica viscosity increased more rapidly with increased volume fraction than predicted by the classical Batchalor and Dougherty-Krieger models. The deviation has been attributed to the secondary electroviscous effect stemming from the electrostatic interactions among sil-ica colloid particle. This has quantitatively been interpreted in terms of the effective hard particle concept used previously to describe densities of particle mono-layers. Explicit de-pendence of the effective particle volume on the double-layer thickness has also been given.

7

Influence of adsorbed colloid particles on streaming potential

Adamczyk Z., Warszyński P., Zembala M.

Bulletin of the Polish Academy of Sciences. Chemistry

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1999

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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.

8

A direct method of studying colloid interactions and adsorption at solid / liquid interfaces

Adamczyk Z., Szyk L., Warszyński P.

Bulletin of the Polish Academy of Sciences. Chemistry

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1998

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Vol. 46, No. 4

425-439

EN

A new cell for direct in situ observations of colloid particle adsorption was developed. The controlled convective transport conditions were created by exploiting the slot impinging jet (SIJ) principle. Numerical solutions of the governing Navier-Stokes equation showed that the flow pattern in the cell can be approximated by the planeparallel stagnation flow with the perpendicular velocity component independent of the lateral distance X. Thus, the solid/liquid interface at distances close to the symmetry plane was found uniformly accessible for particle transport. This flow field was used to derive the mass transport equation which was then numerically solved to obtain the initial flux (adsorption rate) for various transport conditions. These theoretical predictions were verified experimentally using monodisperse polystyrene latex particles. A good agreement between predicted and measured initial flux was found for a broad range of Reynolds number and ionic strength of the particle suspension. This confirmed that the SIJ cell can be used as a useful tool of studying colloid and bioparticle interactions and adsorption under well-defined transport conditions.