Marek Kosmulski - Academia.edu (original) (raw)

Papers by Marek Kosmulski

Research paper thumbnail of Reaction volume in aqueous solutions in problem solving

Annales Universitatis Mariae Curie-Skłodowska, 2015

The volumes of reactions in solution are usually ignored in problem solving. Neglection of reacti... more The volumes of reactions in solution are usually ignored in problem solving. Neglection of reaction volumes may lead to errors on the order of 1 % in the final result. Calculation of the volume of neutralization reaction based on the specific densities of solutions from chemical tables is demonstrated.

Research paper thumbnail of Comment on the paper „Kinetics, equilibrium and isotope exchange in ion exchange systems” by Plicka et al

Comment on the paper „Kinetics, equilibrium and isotope exchange in ion exchange systems” by Plicka et al

Journal of Radioanalytical and Nuclear Chemistry, Apr 1, 1986

ABSTRACT

Research paper thumbnail of A collection of papers presented at the International Symposium on Electrokinetic Phenomena Cracow, Poland, August 18–22, 2002

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Jul 1, 2003

This cyclic symposium was dedicated this time to the memory of Marjan Smoluchowski an outstanding... more This cyclic symposium was dedicated this time to the memory of Marjan Smoluchowski an outstanding Polish physicist and physicochemist (see below for his detailed curriculum vitae). With merely 85 scientific publications he has made outstanding contribution to hydrodynamics, theory of fluctuation, Brownian motion and diffusion, coagulation kinetics and electrokinetic phenomena. The lasting significance of his works is best illustrated by the fact his paper: ''Versuch einer mathematischen Theorie der Koagulationskinetik kolloider Loesungen (attempt at a mathematical theory of coagulation of colloidal solutions)'' published in Zeit. Phys. Chem. 92:129 Á/168 (1917) has been cited over 1500 times. Similarly, the most frequently used relationship in colloid science connecting the electrophoretic mobility and electrokinetic potential is known as Smoluchowski equation.

Research paper thumbnail of Surface Charge and Conductance in Dispersions of Titania in Nonaqueous and Mixed Solvents

Surface Charge and Conductance in Dispersions of Titania in Nonaqueous and Mixed Solvents

Springer eBooks, 2011

The nature and speciation of ions, and their affinities to mineral surfaces are well-known for aq... more The nature and speciation of ions, and their affinities to mineral surfaces are well-known for aqueous solutions, and less well-known for mixed water-organic and nonaqueous solutions. Weak acids show strong preferential adsorption of anions on titania, and support a high negative surface charge on titania particles in organic solvents in spite of the very low degree of dissociation of these acids. The interaction between solutions of weak acids in organic solvents and titania particles results in enhanced electrical conductance with respect to the original solutions (in the absence of titania). This phenomenon is explained in terms of surface-induced electrolytic dissociation of weak acids. In mixed water-organic solvents the conductance behavior gradually shifts from water-like behavior (titania depresses the conductance) to opposite behavior (titania enhances the conductance). A quantitative model was proposed to explain the complex effect of the electrolyte and titania concentration on the conductance of the dispersion and zeta potential of the particles.

Research paper thumbnail of Correlation between the Zeta Potential and Rheological Properties of Anatase Dispersions

Journal of Colloid and Interface Science, 2001

On page 81, the parameter µ appears incorrectly as µu. The corrected text, with µ restored, reads... more On page 81, the parameter µ appears incorrectly as µu. The corrected text, with µ restored, reads as follows: "According to this model, the degree of saturation is given bȳ y = 1/2 1 + (s − 1)/[(1 − s) 2 + 4s/µ] 1/2 , [3]

Research paper thumbnail of The Isoelectric Point of an Exotic Oxide: Tellurium (IV) Oxide

Molecules, May 24, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Novel route of synthesis of Sn-coated SBA-15

Journal of Porous Materials, Oct 3, 2018

A series of Sn-modified SBA-15, was studied. On top of Sn-only modified materials, several materi... more A series of Sn-modified SBA-15, was studied. On top of Sn-only modified materials, several materials were modified with Sn and then Ti or with Sn and then Al. The new materials were obtained by adsorption of vapors of metal chlorides on SBA-15 (at 30-110 °C), and hydrolysis of adsorbed chlorides by water vapor at 25 °C, and then evaporation of left-overs of volatile compounds at 140 °C. The Sn-modified SBA-15 had lower specific surface area, and a higher thermal stability than the original silica. Even in materials containing substantial amount of Sn, the presence of crystalline phases representing Sn compounds was not detected by XRD. In contrast, rutile and anatase were observed in Sn-and Ti-modified SBA-15 while crystalline phases representing Ti compounds were not detected when Ti was deposited directly on SBA-15 (not modified with Sn). The profiles of Sn concentration across the particles of Sn-modified SBA-15 indicate that Sn is located in the pores rather than on the external surface.

Research paper thumbnail of Lanthanides adsorption on controlled pore glass

Journal of Radioanalytical and Nuclear Chemistry, 1990

pore glass from neu%ral and basic solutions. The experiments have been carried out using IO-5M so... more pore glass from neu%ral and basic solutions. The experiments have been carried out using IO-5M solutions of chlorides. For O.IM NaCI as a supporting electrolyte very low adsorption is observed below pH 6 and above pH 8 the ad" sorption curve has a plateau corresponding to over 90% of europium /or cerium/ adsorbed. At lower NaCI concentrations the above pH values shift towards lower values. Europium adsorbs considerably better than cerium and the best selectivity is observed at pH=7.

Research paper thumbnail of Calibration against a reference set: A quantitative approach to assessment of the methods of assessment of scientific output

Calibration against a reference set: A quantitative approach to assessment of the methods of assessment of scientific output

Journal of Informetrics, Jul 1, 2012

ABSTRACT

Research paper thumbnail of Two types of electrokinetic behavior of solid particles in the presence of anionic surfactants

Journal of Colloid and Interface Science, 2019

Research paper thumbnail of Effect of n-alcohols on the electric double layer formed on the surface of controlled pore glass

Journal of Colloid and Interface Science, Jun 1, 1990

Common intersection point of potentiometric titration curves and isoelectric point for the contro... more Common intersection point of potentiometric titration curves and isoelectric point for the controlled pore glass (CPG)-NaC1 system are 3 and 2, respectively; i.e., they are similar to those found for silica. The negative surface charge of CPG is decreased when pure water is replaced by mixed solvents containing water and ethanol, l-propanol, or 1-butanol. The same w/w concentrations of these alcohols lead to approximately equal decreases in the negative surface charges in the system CPG-NaC1 solution for 0.01 and 0.001 M NaG1 concentrations.

Research paper thumbnail of Gender disparity in Polish science by year (1975–2014) and by discipline

Journal of Informetrics, Jul 1, 2015

The production and impact of male and female authors in Poland over the period 1975-2014 have bee... more The production and impact of male and female authors in Poland over the period 1975-2014 have been studied. The method is based on a special property of Polish last names, namely several popular last names have separate masculine (-ski,-cki) and feminine (-ska,-cka) forms. In this respect Polish is different from most other languages, in which the last name has only one form independent of the gender. A set of 56 634 unique publications of authors bearing one of 26 most popular-ski or-cki names was analyzed. The male dominance was observed over the entire studied period, yet it became systematically less significant over the period 1995-2014, especially in terms of production.

Research paper thumbnail of Peculiar charging effects on titania in aqueous 1:1, 2:1, 1:2 and mixed electrolyte suspensions

Advances in Colloid and Interface Science, Nov 1, 2012

Charging of particles in aqueous suspensions is primarily related to potential determining ions, ... more Charging of particles in aqueous suspensions is primarily related to potential determining ions, such as silver and iodide ions at silver halide particle surfaces. Proton is considered as a (secondary) potential determining ion at hydrated metal oxide surfaces. Indifferent electrolytes neutralize at increased concentration the surface charge but do not reverse it. However, in the presence of a non-Coulombic interaction the surface charge may be enhanced or reversed at increased ionic strength. Such interaction is denoted specific which may be due to enhanced van der Waals dipolar, Lewis acid-base, solvation (Hofmeister) and/or Born solvation effects. Alternatively, these interactions have been characterized in terms of (semi) empirical ion and surface properties, such as hard-soft acid-base (HSAB) interaction. Within the Stern layer closest to the particle surface truly specific effects are related to the inner Helmholtz plane (IHP) in order to distinguish them from the charge and solvation related effects occurring within the outer Helmholtz plane (OHP). We review some recent observations on the particular influence of ions on the charging of titania particles in aqueous 1:1, 2:1, 1:2 and mixed electrolyte suspensions.

Research paper thumbnail of Comment on “Point of zero charge of a corundum-water interface probed with optical second harmonic generation (SHG) and atomic force microscopy (AFM): new approaches to oxide surface charge” by A. G. Stack, S. R. Higgins, and C. M. Eggleston

Comment on “Point of zero charge of a corundum-water interface probed with optical second harmonic generation (SHG) and atomic force microscopy (AFM): new approaches to oxide surface charge” by A. G. Stack, S. R. Higgins, and C. M. Eggleston

Geochimica et Cosmochimica Acta, 2003

Research paper thumbnail of The Specific Adsorption of Sodium Cations on Less Common Metal Oxides at High Ionic Strengths

Journal of Colloid and Interface Science, Apr 1, 2002

Sodium cations adsorb specifically on metal oxides at high ionic strengths. This results in a shi... more Sodium cations adsorb specifically on metal oxides at high ionic strengths. This results in a shift in the isoelectric point (IEP) to higher pH values. When the critical concentration of electrolyte is exceeded there is no IEP at all and the electrokinetic potential is positive even at very high pH values. The critical NaI concentration is rather insensitive to the nature of the metal oxide (but silica behaves differently), and this suggests that the specific adsorption is chiefly due to ion-ion and ion-solvent interaction in solution. The experimental results obtained with indium and niobium oxides (critical concentrations of about 0.35 mol dm −3) confirmed this trend.

Research paper thumbnail of High ionic strength electrokinetics of anatase in the presence of multivalent inorganic ions

High ionic strength electrokinetics of anatase in the presence of multivalent inorganic ions

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Nov 1, 2004

ABSTRACT Shifts in the IEP of anatase induced by various combinations of 1:1 electrolytes (at con... more ABSTRACT Shifts in the IEP of anatase induced by various combinations of 1:1 electrolytes (at concentration of 0.5 mol dm−3) and multivalent ions (concentrations in millimolar range) were studied. The high ionic strength enhanced the shift in the IEP of anatase to high pH induced by specific adsorption of barium and suppressed the shift in the IEP of anatase to low pH induced by specific adsorption of phosphate. The ζ potential of anatase at pH 3–5 is nearly zero in the presence of 0.01 mol dm−3 of sulfate at low ionic strength, but it assumes a positive value as high as 15 mV in the presence of 0.5 mol dm−3 NaI at otherwise the same conditions. Apparently, the contribution of 1:1 electrolytes to the surface charging at high ionic strengths is not mere neutralisation of the proton charge.

Research paper thumbnail of Effect of n-alcohols on the surface charge density and adsorption of supporting electrolyte on aluminas

Journal of Colloid and Interface Science, Mar 1, 1990

The presence of n-alcohols (ethanol up to 12, propanol up to 10, and butanol up to 4% weight) doe... more The presence of n-alcohols (ethanol up to 12, propanol up to 10, and butanol up to 4% weight) does not affect the course of the a0 vs. pH curves and the adsorption ofNa + and C1 ions from 0.1, 0.01, and 0.001 M solutions in the system alumina-NaC1 solution. For the sample of alumina containing mainly a-corundum the values of pzc and cip coincide at pH = 8. This sample adsorbs considerable amounts of counterions in relation to the values of o0 but adsorption of these ions at pHpzo is negligible within experimental error. For the sample containing mainly y-alumina, pUei p = 8.2 and o0 =-0.3 C/g for cip. This sample adsorbs considerable amounts of chloride ions even at pHpze but adsorption of sodium ions appears for the pH values above pHpze.

Research paper thumbnail of Confirmation of the Differentiating Effect of Small Cations in the Shift of the Isoelectric Point of Oxides at High Ionic Strengths

Langmuir, Dec 21, 2001

High concentrations of certain 1-1 electrolytes in water induce a shift in the isoelectric point ... more High concentrations of certain 1-1 electrolytes in water induce a shift in the isoelectric point (IEP) of metal oxides to pH values substantially higher than the pristine IEP. With large cations, the nature of the anion does not affect the magnitude of these shifts, but with Li and Na the shift depends on the nature of the anion. This effect is termed the differentiating effect of small cations, and it has been studied in detail for anatase. The present results confirm the existence of the differentiating effect of Na for alumina. The anion sequence I > Br > Cl > ClO4 > NO3 observed for alumina is identical with that reported for anatase.

Research paper thumbnail of Effect of n-alcohols on the potentiometric titrations of rutile

Effect of n-alcohols on the potentiometric titrations of rutile

Journal of Colloid and Interface Science, Dec 1, 1988

ABSTRACT

Research paper thumbnail of Charge interactions in semi-concentrated titania suspensions at very high ionic strengths

Charge interactions in semi-concentrated titania suspensions at very high ionic strengths

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Oct 1, 1999

ABSTRACT ζ-Potentials of titania particles in aqueous suspensions containing up to 1.2 mol dm−3 1... more ABSTRACT ζ-Potentials of titania particles in aqueous suspensions containing up to 1.2 mol dm−3 1-1 electrolyte are reported. At sufficiently high concentrations of supporting inert electrolytes (>0.1 mol dm−3), the isoelectric point (i.e.p.) of titania shifts toward higher pH values. At even higher ionic strength the ζ-potential of the titania particles are positive even at pH>10 (no i.e.p.). The lowest concentration at which such an effect is observed ranges from 0.5 mol dm−3 for NaI to 0.9 mol dm−3 for NaNO3 and over 0.9 mol dm−3 for NaCl. In mixed solvents, e.g. 30% methanol-70% water, similar effects are observed at substantially lower ionic strengths than in purely aqueous systems. The acidic branch of the ζ(pH) curves is much less sensitive than the alkaline branch to the electrolyte concentration in aqueous and mixed solvent systems. The effect of the supporting electrolyte is evaluated experimentally and discussed in relation to recently published results on the properties of suspensions of relatively high solids fraction.

Research paper thumbnail of Reaction volume in aqueous solutions in problem solving

Annales Universitatis Mariae Curie-Skłodowska, 2015

The volumes of reactions in solution are usually ignored in problem solving. Neglection of reacti... more The volumes of reactions in solution are usually ignored in problem solving. Neglection of reaction volumes may lead to errors on the order of 1 % in the final result. Calculation of the volume of neutralization reaction based on the specific densities of solutions from chemical tables is demonstrated.

Research paper thumbnail of Comment on the paper „Kinetics, equilibrium and isotope exchange in ion exchange systems” by Plicka et al

Comment on the paper „Kinetics, equilibrium and isotope exchange in ion exchange systems” by Plicka et al

Journal of Radioanalytical and Nuclear Chemistry, Apr 1, 1986

ABSTRACT

Research paper thumbnail of A collection of papers presented at the International Symposium on Electrokinetic Phenomena Cracow, Poland, August 18–22, 2002

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Jul 1, 2003

This cyclic symposium was dedicated this time to the memory of Marjan Smoluchowski an outstanding... more This cyclic symposium was dedicated this time to the memory of Marjan Smoluchowski an outstanding Polish physicist and physicochemist (see below for his detailed curriculum vitae). With merely 85 scientific publications he has made outstanding contribution to hydrodynamics, theory of fluctuation, Brownian motion and diffusion, coagulation kinetics and electrokinetic phenomena. The lasting significance of his works is best illustrated by the fact his paper: ''Versuch einer mathematischen Theorie der Koagulationskinetik kolloider Loesungen (attempt at a mathematical theory of coagulation of colloidal solutions)'' published in Zeit. Phys. Chem. 92:129 Á/168 (1917) has been cited over 1500 times. Similarly, the most frequently used relationship in colloid science connecting the electrophoretic mobility and electrokinetic potential is known as Smoluchowski equation.

Research paper thumbnail of Surface Charge and Conductance in Dispersions of Titania in Nonaqueous and Mixed Solvents

Surface Charge and Conductance in Dispersions of Titania in Nonaqueous and Mixed Solvents

Springer eBooks, 2011

The nature and speciation of ions, and their affinities to mineral surfaces are well-known for aq... more The nature and speciation of ions, and their affinities to mineral surfaces are well-known for aqueous solutions, and less well-known for mixed water-organic and nonaqueous solutions. Weak acids show strong preferential adsorption of anions on titania, and support a high negative surface charge on titania particles in organic solvents in spite of the very low degree of dissociation of these acids. The interaction between solutions of weak acids in organic solvents and titania particles results in enhanced electrical conductance with respect to the original solutions (in the absence of titania). This phenomenon is explained in terms of surface-induced electrolytic dissociation of weak acids. In mixed water-organic solvents the conductance behavior gradually shifts from water-like behavior (titania depresses the conductance) to opposite behavior (titania enhances the conductance). A quantitative model was proposed to explain the complex effect of the electrolyte and titania concentration on the conductance of the dispersion and zeta potential of the particles.

Research paper thumbnail of Correlation between the Zeta Potential and Rheological Properties of Anatase Dispersions

Journal of Colloid and Interface Science, 2001

On page 81, the parameter µ appears incorrectly as µu. The corrected text, with µ restored, reads... more On page 81, the parameter µ appears incorrectly as µu. The corrected text, with µ restored, reads as follows: "According to this model, the degree of saturation is given bȳ y = 1/2 1 + (s − 1)/[(1 − s) 2 + 4s/µ] 1/2 , [3]

Research paper thumbnail of The Isoelectric Point of an Exotic Oxide: Tellurium (IV) Oxide

Molecules, May 24, 2021

This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY

Research paper thumbnail of Novel route of synthesis of Sn-coated SBA-15

Journal of Porous Materials, Oct 3, 2018

A series of Sn-modified SBA-15, was studied. On top of Sn-only modified materials, several materi... more A series of Sn-modified SBA-15, was studied. On top of Sn-only modified materials, several materials were modified with Sn and then Ti or with Sn and then Al. The new materials were obtained by adsorption of vapors of metal chlorides on SBA-15 (at 30-110 °C), and hydrolysis of adsorbed chlorides by water vapor at 25 °C, and then evaporation of left-overs of volatile compounds at 140 °C. The Sn-modified SBA-15 had lower specific surface area, and a higher thermal stability than the original silica. Even in materials containing substantial amount of Sn, the presence of crystalline phases representing Sn compounds was not detected by XRD. In contrast, rutile and anatase were observed in Sn-and Ti-modified SBA-15 while crystalline phases representing Ti compounds were not detected when Ti was deposited directly on SBA-15 (not modified with Sn). The profiles of Sn concentration across the particles of Sn-modified SBA-15 indicate that Sn is located in the pores rather than on the external surface.

Research paper thumbnail of Lanthanides adsorption on controlled pore glass

Journal of Radioanalytical and Nuclear Chemistry, 1990

pore glass from neu%ral and basic solutions. The experiments have been carried out using IO-5M so... more pore glass from neu%ral and basic solutions. The experiments have been carried out using IO-5M solutions of chlorides. For O.IM NaCI as a supporting electrolyte very low adsorption is observed below pH 6 and above pH 8 the ad" sorption curve has a plateau corresponding to over 90% of europium /or cerium/ adsorbed. At lower NaCI concentrations the above pH values shift towards lower values. Europium adsorbs considerably better than cerium and the best selectivity is observed at pH=7.

Research paper thumbnail of Calibration against a reference set: A quantitative approach to assessment of the methods of assessment of scientific output

Calibration against a reference set: A quantitative approach to assessment of the methods of assessment of scientific output

Journal of Informetrics, Jul 1, 2012

ABSTRACT

Research paper thumbnail of Two types of electrokinetic behavior of solid particles in the presence of anionic surfactants

Journal of Colloid and Interface Science, 2019

Research paper thumbnail of Effect of n-alcohols on the electric double layer formed on the surface of controlled pore glass

Journal of Colloid and Interface Science, Jun 1, 1990

Common intersection point of potentiometric titration curves and isoelectric point for the contro... more Common intersection point of potentiometric titration curves and isoelectric point for the controlled pore glass (CPG)-NaC1 system are 3 and 2, respectively; i.e., they are similar to those found for silica. The negative surface charge of CPG is decreased when pure water is replaced by mixed solvents containing water and ethanol, l-propanol, or 1-butanol. The same w/w concentrations of these alcohols lead to approximately equal decreases in the negative surface charges in the system CPG-NaC1 solution for 0.01 and 0.001 M NaG1 concentrations.

Research paper thumbnail of Gender disparity in Polish science by year (1975–2014) and by discipline

Journal of Informetrics, Jul 1, 2015

The production and impact of male and female authors in Poland over the period 1975-2014 have bee... more The production and impact of male and female authors in Poland over the period 1975-2014 have been studied. The method is based on a special property of Polish last names, namely several popular last names have separate masculine (-ski,-cki) and feminine (-ska,-cka) forms. In this respect Polish is different from most other languages, in which the last name has only one form independent of the gender. A set of 56 634 unique publications of authors bearing one of 26 most popular-ski or-cki names was analyzed. The male dominance was observed over the entire studied period, yet it became systematically less significant over the period 1995-2014, especially in terms of production.

Research paper thumbnail of Peculiar charging effects on titania in aqueous 1:1, 2:1, 1:2 and mixed electrolyte suspensions

Advances in Colloid and Interface Science, Nov 1, 2012

Charging of particles in aqueous suspensions is primarily related to potential determining ions, ... more Charging of particles in aqueous suspensions is primarily related to potential determining ions, such as silver and iodide ions at silver halide particle surfaces. Proton is considered as a (secondary) potential determining ion at hydrated metal oxide surfaces. Indifferent electrolytes neutralize at increased concentration the surface charge but do not reverse it. However, in the presence of a non-Coulombic interaction the surface charge may be enhanced or reversed at increased ionic strength. Such interaction is denoted specific which may be due to enhanced van der Waals dipolar, Lewis acid-base, solvation (Hofmeister) and/or Born solvation effects. Alternatively, these interactions have been characterized in terms of (semi) empirical ion and surface properties, such as hard-soft acid-base (HSAB) interaction. Within the Stern layer closest to the particle surface truly specific effects are related to the inner Helmholtz plane (IHP) in order to distinguish them from the charge and solvation related effects occurring within the outer Helmholtz plane (OHP). We review some recent observations on the particular influence of ions on the charging of titania particles in aqueous 1:1, 2:1, 1:2 and mixed electrolyte suspensions.

Research paper thumbnail of Comment on “Point of zero charge of a corundum-water interface probed with optical second harmonic generation (SHG) and atomic force microscopy (AFM): new approaches to oxide surface charge” by A. G. Stack, S. R. Higgins, and C. M. Eggleston

Comment on “Point of zero charge of a corundum-water interface probed with optical second harmonic generation (SHG) and atomic force microscopy (AFM): new approaches to oxide surface charge” by A. G. Stack, S. R. Higgins, and C. M. Eggleston

Geochimica et Cosmochimica Acta, 2003

Research paper thumbnail of The Specific Adsorption of Sodium Cations on Less Common Metal Oxides at High Ionic Strengths

Journal of Colloid and Interface Science, Apr 1, 2002

Sodium cations adsorb specifically on metal oxides at high ionic strengths. This results in a shi... more Sodium cations adsorb specifically on metal oxides at high ionic strengths. This results in a shift in the isoelectric point (IEP) to higher pH values. When the critical concentration of electrolyte is exceeded there is no IEP at all and the electrokinetic potential is positive even at very high pH values. The critical NaI concentration is rather insensitive to the nature of the metal oxide (but silica behaves differently), and this suggests that the specific adsorption is chiefly due to ion-ion and ion-solvent interaction in solution. The experimental results obtained with indium and niobium oxides (critical concentrations of about 0.35 mol dm −3) confirmed this trend.

Research paper thumbnail of High ionic strength electrokinetics of anatase in the presence of multivalent inorganic ions

High ionic strength electrokinetics of anatase in the presence of multivalent inorganic ions

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Nov 1, 2004

ABSTRACT Shifts in the IEP of anatase induced by various combinations of 1:1 electrolytes (at con... more ABSTRACT Shifts in the IEP of anatase induced by various combinations of 1:1 electrolytes (at concentration of 0.5 mol dm−3) and multivalent ions (concentrations in millimolar range) were studied. The high ionic strength enhanced the shift in the IEP of anatase to high pH induced by specific adsorption of barium and suppressed the shift in the IEP of anatase to low pH induced by specific adsorption of phosphate. The ζ potential of anatase at pH 3–5 is nearly zero in the presence of 0.01 mol dm−3 of sulfate at low ionic strength, but it assumes a positive value as high as 15 mV in the presence of 0.5 mol dm−3 NaI at otherwise the same conditions. Apparently, the contribution of 1:1 electrolytes to the surface charging at high ionic strengths is not mere neutralisation of the proton charge.

Research paper thumbnail of Effect of n-alcohols on the surface charge density and adsorption of supporting electrolyte on aluminas

Journal of Colloid and Interface Science, Mar 1, 1990

The presence of n-alcohols (ethanol up to 12, propanol up to 10, and butanol up to 4% weight) doe... more The presence of n-alcohols (ethanol up to 12, propanol up to 10, and butanol up to 4% weight) does not affect the course of the a0 vs. pH curves and the adsorption ofNa + and C1 ions from 0.1, 0.01, and 0.001 M solutions in the system alumina-NaC1 solution. For the sample of alumina containing mainly a-corundum the values of pzc and cip coincide at pH = 8. This sample adsorbs considerable amounts of counterions in relation to the values of o0 but adsorption of these ions at pHpzo is negligible within experimental error. For the sample containing mainly y-alumina, pUei p = 8.2 and o0 =-0.3 C/g for cip. This sample adsorbs considerable amounts of chloride ions even at pHpze but adsorption of sodium ions appears for the pH values above pHpze.

Research paper thumbnail of Confirmation of the Differentiating Effect of Small Cations in the Shift of the Isoelectric Point of Oxides at High Ionic Strengths

Langmuir, Dec 21, 2001

High concentrations of certain 1-1 electrolytes in water induce a shift in the isoelectric point ... more High concentrations of certain 1-1 electrolytes in water induce a shift in the isoelectric point (IEP) of metal oxides to pH values substantially higher than the pristine IEP. With large cations, the nature of the anion does not affect the magnitude of these shifts, but with Li and Na the shift depends on the nature of the anion. This effect is termed the differentiating effect of small cations, and it has been studied in detail for anatase. The present results confirm the existence of the differentiating effect of Na for alumina. The anion sequence I > Br > Cl > ClO4 > NO3 observed for alumina is identical with that reported for anatase.

Research paper thumbnail of Effect of n-alcohols on the potentiometric titrations of rutile

Effect of n-alcohols on the potentiometric titrations of rutile

Journal of Colloid and Interface Science, Dec 1, 1988

ABSTRACT

Research paper thumbnail of Charge interactions in semi-concentrated titania suspensions at very high ionic strengths

Charge interactions in semi-concentrated titania suspensions at very high ionic strengths

Colloids and Surfaces A: Physicochemical and Engineering Aspects, Oct 1, 1999

ABSTRACT ζ-Potentials of titania particles in aqueous suspensions containing up to 1.2 mol dm−3 1... more ABSTRACT ζ-Potentials of titania particles in aqueous suspensions containing up to 1.2 mol dm−3 1-1 electrolyte are reported. At sufficiently high concentrations of supporting inert electrolytes (>0.1 mol dm−3), the isoelectric point (i.e.p.) of titania shifts toward higher pH values. At even higher ionic strength the ζ-potential of the titania particles are positive even at pH>10 (no i.e.p.). The lowest concentration at which such an effect is observed ranges from 0.5 mol dm−3 for NaI to 0.9 mol dm−3 for NaNO3 and over 0.9 mol dm−3 for NaCl. In mixed solvents, e.g. 30% methanol-70% water, similar effects are observed at substantially lower ionic strengths than in purely aqueous systems. The acidic branch of the ζ(pH) curves is much less sensitive than the alkaline branch to the electrolyte concentration in aqueous and mixed solvent systems. The effect of the supporting electrolyte is evaluated experimentally and discussed in relation to recently published results on the properties of suspensions of relatively high solids fraction.