Non-monotonic concentration dependence of the electro-phoretic mobility of charged spheres in realistic salt free suspensions

Abstract

Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the optically accessible range of concentrations in experiments on colloidal electro-kinetics. Here, we measured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic concentration dependence of the mobility for a single particle species. Our observations reconcile previous experimental observations made on other species over restricted concentration ranges. We compare our results to the state-of-the-art theoretical calculations using a constant particle charge and the carefully determined experimental boundary conditions as input. In particular, we consider the so-called realistic salt free conditions, i.e., we respect the release of counterions by the particles, the solvent hydrolysis, and the formation of carbonic acid from dissolved neutral CO2. We also compare our results to previous results obtained under similarly well-defined conditions. This allows identification of three distinct regions of differing density dependence. There is an ascent during the build-up of double layer overlap, which is not expected by theory, an extended plateau region in quantitative agreement with theoretical expectation based on a constant effective charge and a sudden decrease, which occurs way before the expected gradual decrease. Our observations suggest a relation of the non-monotonic behavior to a decrease in particle charge, and we tentatively discuss possibly underlying mechanisms.

Autoren

Denis Botin
Felix Carrique
Emilio Ruiz-Reina
Thomas Palberg

DOI

10.1063/5.0010692

eISSN

1089-7690

ISSN

0021-9606

Ausgabe der Veröffentlichung

24

Zeitschrift

The Journal of Chemical Physics

Sprache

en

Online publication date

2020

Datum der Veröffentlichung

2020

Status

Published

Herausgeber

AIP Publishing

Herausgeber URL

http://dx.doi.org/10.1063/5.0010692

Datum der Datenerfassung

2023

Titel

Non-monotonic concentration dependence of the electro-phoretic mobility of charged spheres in realistic salt free suspensions

Ausgabe der Zeitschrift

152

Datenquelle: Crossref

Abstract

Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the optically accessible range of concentrations in experiments on colloidal electro-kinetics. Here, we measured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic concentration dependence of the mobility for a single particle species. Our observations reconcile previous experimental observations made on other species over restricted concentration ranges. We compare our results to the state-of-the-art theoretical calculations using a constant particle charge and the carefully determined experimental boundary conditions as input. In particular, we consider the so-called realistic salt free conditions, i.e., we respect the release of counterions by the particles, the solvent hydrolysis, and the formation of carbonic acid from dissolved neutral CO<sub>2</sub>. We also compare our results to previous results obtained under similarly well-defined conditions. This allows identification of three distinct regions of differing density dependence. There is an ascent during the build-up of double layer overlap, which is not expected by theory, an extended plateau region in quantitative agreement with theoretical expectation based on a constant effective charge and a sudden decrease, which occurs way before the expected gradual decrease. Our observations suggest a relation of the non-monotonic behavior to a decrease in particle charge, and we tentatively discuss possibly underlying mechanisms.

Addresses

Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany.

Autoren

Denis Botin
Felix Carrique
Emilio Ruiz-Reina
Thomas Palberg

DOI

10.1063/5.0010692

eISSN

1089-7690

Externe Identifier

PubMed Identifier: 32610949

Funding acknowledgements

Deutsche Forschungsgemeinschaft: PA 459/18-1
European Regional Development Fund: SOMM17/6105/UGR
Consejriá de Conocimiento, Investigatión y Universidad, Junta de Andalucia:
IC1 University Granada:
Deutsche Forschungsgemeinschaft: PA 459/18-2

Open access

false

ISSN

0021-9606

Ausgabe der Veröffentlichung

24

Zeitschrift

The Journal of chemical physics

Sprache

eng

Medium

Print

Paginierung

244902

Datum der Veröffentlichung

2020

Status

Published

Datum der Datenerfassung

2020

Titel

Non-monotonic concentration dependence of the electro-phoretic mobility of charged spheres in realistic salt free suspensions.

Sub types

Journal Article

Ausgabe der Zeitschrift

152

Datenquelle: Europe PubMed Central

Abstract

Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the optically accessible range of concentrations in experiments on colloidal electro-kinetics. Here, we measured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic concentration dependence of the mobility for a single particle species. Our observations reconcile previous experimental observations made on other species over restricted concentration ranges. We compare our results to the state-of-the-art theoretical calculations using a constant particle charge and the carefully determined experimental boundary conditions as input. In particular, we consider the so-called realistic salt free conditions, i.e., we respect the release of counterions by the particles, the solvent hydrolysis, and the formation of carbonic acid from dissolved neutral CO2. We also compare our results to previous results obtained under similarly well-defined conditions. This allows identification of three distinct regions of differing density dependence. There is an ascent during the build-up of double layer overlap, which is not expected by theory, an extended plateau region in quantitative agreement with theoretical expectation based on a constant effective charge and a sudden decrease, which occurs way before the expected gradual decrease. Our observations suggest a relation of the non-monotonic behavior to a decrease in particle charge, and we tentatively discuss possibly underlying mechanisms.

Autoren

Denis Botin
Felix Carrique
Emilio Ruiz-Reina
Thomas Palberg

Autoren-URL

https://www.ncbi.nlm.nih.gov/pubmed/32610949

DOI

10.1063/5.0010692

eISSN

1089-7690

Ausgabe der Veröffentlichung

24

Zeitschrift

J Chem Phys

Sprache

eng

Country

United States

Paginierung

244902

Datum der Veröffentlichung

2020

Status

Published

Titel

Non-monotonic concentration dependence of the electro-phoretic mobility of charged spheres in realistic salt free suspensions.

Sub types

Journal Article

Ausgabe der Zeitschrift

152

Datenquelle: PubMed

Abstract

Using super-heterodyne Doppler velocimetry with multiple scattering correction, we extend the opti-cally accessible range of concentrations in experiments on colloidal electro-kinetics. We here meas-ured the electro-phoretic mobility and the DC conductivity of aqueous charged sphere suspensions covering about three orders of magnitude in particle concentrations and transmissions as low as 40%. The extended concentration range for the first time allows the demonstration of a non-monotonic con-centration dependence of the mobility for a single particle species. Our observations reconcile previ-ous experimental observations made on other species over restricted concentration ranges. We com-pare our results to state of the art theoretical calculations using a constant particle charge and the carefully determined experimental boundary conditions as input. In particular, we consider so-called realistic salt free conditions, i.e. we respect the release of counter-ions by the particles, the solvent hydrolysis and the formation of carbonic acid from dissolved neutral CO2. We also compare to previ-ous results obtained under similarly well-defined conditions. This allows identification of three dis-tinct regions of differing density dependence. An ascent during the built up of double layer overlap which is not expected by theory, an extended plateau region in quantitative agreement with theoretical expectation based on a constant effective charge and a sudden decrease which occurs way before the expected gradual decrease. Our observations suggest a relation of the non-monotonic behavior to a decrease of particle charge, and we tentatively discuss possibly underlying mechanisms.

Autoren

Denis Botin
Felix Carrique
Emilio Ruiz-Reina
Thomas Palberg

Autoren-URL

http://arxiv.org/abs/1912.05244v2

Schlüsselwörter

cond-mat.soft
cond-mat.soft
cond-mat.stat-mech
physics.chem-ph

Notes

Regular article 20 MS Pages 6 Figures 88 references

Datum der Veröffentlichung

2019

Herausgeber URL

http://dx.doi.org/10.1063/5.0010692

Datum der Datenerfassung

2019

Datum, an dem der Datensatz öffentlich gemacht wurde

2019

Titel

Non-Monotonic Concentration Dependence of the Electro-Phoretic Mobility of Charged Spheres in Realistic Salt Free Suspensions

Files

1912.05244v2.pdf

Datenquelle: arXiv

Non-monotonic concentration dependence of the electro-phoretic mobility of charged spheres in realistic salt free suspensions

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