Coagulation rate of silica dispersions investigated by single-particle optical sizing

S. Bárány, Martien A. Cohen Stuart, Gerard J. Fleer

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Using a single-particle optical sizer, the kinetics of the rapid coagulation of monodisperse silica particles of radius 265 nm in KCl and CaCl2 solutions was studied. The rate constant k11 of the process is 1.7 x 10-12 cm3 s-1, which is three times smaller than the Smoluchowski value for the overall rate constant. This discrepancy is explained by the retardation effect of viscous interactions and the existence of long-range attractive forces between particles. For suspensions with an initial particle concentration between 2.5 x 108 and 2.4 x 109 cm-3, the k11 values are independent of the pH value (in the range 7-10) and of the particle number concentration. The ratio between the coagulation concentrations of monovalent and bivalent counterions is 50, under both perikinetic and orthokinetic conditions, which indicates that this silica suspension is electrostatically stabilized. This is in contrast to literature data for very small SiO2 particles. We propose that the so-called 'structural' forces are much less important for large silica particles.

Original languageEnglish
Pages (from-to)213-221
Number of pages9
JournalColloids and Surfaces A: Physicochemical and Engineering Aspects
Volume106
Issue number2-3
DOIs
Publication statusPublished - Jan 22 1996

Fingerprint

sizing
coagulation
Coagulation
Dispersions
Silicon Dioxide
Silica
silicon dioxide
Rate constants
Suspensions
Kinetics
radii
kinetics

Keywords

  • coagulation rate
  • dispersions
  • silica
  • single-particle optical sizing

ASJC Scopus subject areas

  • Colloid and Surface Chemistry
  • Physical and Theoretical Chemistry

Cite this

Coagulation rate of silica dispersions investigated by single-particle optical sizing. / Bárány, S.; Cohen Stuart, Martien A.; Fleer, Gerard J.

In: Colloids and Surfaces A: Physicochemical and Engineering Aspects, Vol. 106, No. 2-3, 22.01.1996, p. 213-221.

Research output: Contribution to journalArticle

@article{4aa6ddb6c6494fc9a54f1044f124ce97,
title = "Coagulation rate of silica dispersions investigated by single-particle optical sizing",
abstract = "Using a single-particle optical sizer, the kinetics of the rapid coagulation of monodisperse silica particles of radius 265 nm in KCl and CaCl2 solutions was studied. The rate constant k11 of the process is 1.7 x 10-12 cm3 s-1, which is three times smaller than the Smoluchowski value for the overall rate constant. This discrepancy is explained by the retardation effect of viscous interactions and the existence of long-range attractive forces between particles. For suspensions with an initial particle concentration between 2.5 x 108 and 2.4 x 109 cm-3, the k11 values are independent of the pH value (in the range 7-10) and of the particle number concentration. The ratio between the coagulation concentrations of monovalent and bivalent counterions is 50, under both perikinetic and orthokinetic conditions, which indicates that this silica suspension is electrostatically stabilized. This is in contrast to literature data for very small SiO2 particles. We propose that the so-called 'structural' forces are much less important for large silica particles.",
keywords = "coagulation rate, dispersions, silica, single-particle optical sizing",
author = "S. B{\'a}r{\'a}ny and {Cohen Stuart}, {Martien A.} and Fleer, {Gerard J.}",
year = "1996",
month = "1",
day = "22",
doi = "10.1016/0927-7757(95)03376-9",
language = "English",
volume = "106",
pages = "213--221",
journal = "Colloids and Surfaces A: Physicochemical and Engineering Aspects",
issn = "0927-7757",
publisher = "Elsevier",
number = "2-3",

}

TY - JOUR

T1 - Coagulation rate of silica dispersions investigated by single-particle optical sizing

AU - Bárány, S.

AU - Cohen Stuart, Martien A.

AU - Fleer, Gerard J.

PY - 1996/1/22

Y1 - 1996/1/22

N2 - Using a single-particle optical sizer, the kinetics of the rapid coagulation of monodisperse silica particles of radius 265 nm in KCl and CaCl2 solutions was studied. The rate constant k11 of the process is 1.7 x 10-12 cm3 s-1, which is three times smaller than the Smoluchowski value for the overall rate constant. This discrepancy is explained by the retardation effect of viscous interactions and the existence of long-range attractive forces between particles. For suspensions with an initial particle concentration between 2.5 x 108 and 2.4 x 109 cm-3, the k11 values are independent of the pH value (in the range 7-10) and of the particle number concentration. The ratio between the coagulation concentrations of monovalent and bivalent counterions is 50, under both perikinetic and orthokinetic conditions, which indicates that this silica suspension is electrostatically stabilized. This is in contrast to literature data for very small SiO2 particles. We propose that the so-called 'structural' forces are much less important for large silica particles.

AB - Using a single-particle optical sizer, the kinetics of the rapid coagulation of monodisperse silica particles of radius 265 nm in KCl and CaCl2 solutions was studied. The rate constant k11 of the process is 1.7 x 10-12 cm3 s-1, which is three times smaller than the Smoluchowski value for the overall rate constant. This discrepancy is explained by the retardation effect of viscous interactions and the existence of long-range attractive forces between particles. For suspensions with an initial particle concentration between 2.5 x 108 and 2.4 x 109 cm-3, the k11 values are independent of the pH value (in the range 7-10) and of the particle number concentration. The ratio between the coagulation concentrations of monovalent and bivalent counterions is 50, under both perikinetic and orthokinetic conditions, which indicates that this silica suspension is electrostatically stabilized. This is in contrast to literature data for very small SiO2 particles. We propose that the so-called 'structural' forces are much less important for large silica particles.

KW - coagulation rate

KW - dispersions

KW - silica

KW - single-particle optical sizing

UR - http://www.scopus.com/inward/record.url?scp=0029970501&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0029970501&partnerID=8YFLogxK

U2 - 10.1016/0927-7757(95)03376-9

DO - 10.1016/0927-7757(95)03376-9

M3 - Article

AN - SCOPUS:0029970501

VL - 106

SP - 213

EP - 221

JO - Colloids and Surfaces A: Physicochemical and Engineering Aspects

JF - Colloids and Surfaces A: Physicochemical and Engineering Aspects

SN - 0927-7757

IS - 2-3

ER -