Flow behavior of coagulated colloidal sols. V. Dynamics of floc growth under shear

Hunter, Robert J.; Frayne, J. G.

doi:10.1016/0021-9797(80)90275-1

Cited by 65 publications

(34 citation statements)

References 8 publications

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“…The conclusion, that the final aggregate size increases with increasing 7, is contrary to the findings of Hunter and Frayne [20]. However, in their experiments floes were formed during ultrasonication preceding the shear application.…”

Section: The Final Coagulation Stagescontrasting

confidence: 68%

Coagulation of suspensions in shear fields of different characters

Stein

Logtenberg

Diemen

et al. 1986

Colloids and Surfaces

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Section: The Final Coagulation Stagescontrasting

confidence: 68%

Coagulation of suspensions in shear fields of different characters

Stein

Logtenberg

Diemen

et al. 1986

Colloids and Surfaces

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“…In the latter, the character of the glass surface clearly effects coagulation. A calculation of the interaction parameters according to Firth and Hunter (4-6) or Hunter and Frayne (8) was not attempted because it is rather problematic whether the assumptions of these authors apply to the systems concerned. Thus, on microscopic examination our suspensions of hydrophobic glass in glycerol + water mixtures were found to contain, in addition to agglomerates, quite a large number of single particles; furthermore, in the Hunter and Frayne analysis an important parameter, the "floc volume ratio" is calculated from the plastic viscosity by applying the Einstein relation, on the assumption that interactions between flocs influence only To.…”

Section: Discussionmentioning

confidence: 99%

“…Van de Ven and Hunter (7) could account for this energy dissipation through fluid movement inside flocs during collisions. Such fluid motion, however, is not independent of the mutual velocity of the flocs during collisions; it would lead to an energy dissipation during a collision which would be proportional to D and thus would give rise to an energy dissipation per unit of volume and time proportional to D 2, if the floc size is independent of D. However, Hunter and Frayne (8) report that the floc radius is a proportional to D -°'41 such as to make aoDa 2 independent ofD ; this leads to an energy dissipation per unit of volume and time proportional to D.…”

Section: Introductionmentioning

confidence: 99%

Energy dissipation during stationary flow of suspensions of hydrophilic and hydrophobic glass spheres in organic liquids

Diemen¹,

Stein²

1982

Journal of Colloid and Interface Science

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Suspensions of both hydrophilic and hydrophobic glass spheres in dioctylphthalate behave similarly to suspensions of hydrophilic glass spheres in glycerol + water mixtures: Newtonian behavior is shown up to a solid volume fraction (Cv) of 0.4; at larger Cv values, Bingham behavior is observed with a yield value steeply increasing at cv > 0.45. Suspensions of hydrophobic glass spheres in glycerol + water mixtures, on the other hand, already show deviations from Newtonian behavior at Cv < 0.1. The phenomena indicate absence of coagulation in dioctylphthalate. The number of collisions between the glass spheres in noncoagulating suspensions with 0.45 < Cv < 0.58 is calculated. That part of the energy dissipated per collision, which is independent of the mutual velocity of the colliding particles, cannot be accounted for by the attractive potential energy between the spheres as calculated by the Hamaker equation; in this respect the situation is analogous to that observed on floc formation in coagulating suspensions. It is suggested that the energy dissipation concerned is caused by the motion of spheres in the vicinity of a colliding pair, with the number of spheres entrained decreasing with increasing mutual velocity of the colliding spheres.

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“…5). Firth et al 27,28) obtained the value of f h /f w as 10.5 for aqueous suspension of kaolinite from plastic viscosity, attributing this large value to the anisometric nature of the kaolinite particles. In this work, the largest value (2.6) emanates from bridging effect at low concentration of PVP (0.001%), the smallest (1.4) from the dispersing property at concentrations of PVP (0.1-0.8 g/dl) and SLI (10-12 mM).…”

Section: Bingham Yield Valuementioning

confidence: 99%

Effect of Polyvinylpyrrolidone and Sodium Lauroyl Isethionate on Kaolinite Suspension in an Aqueous Phase

Kwan

Chu

Shimabayashi

2006

CHEMICAL & PHARMACEUTICAL BULLETIN

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Kaolinite is a very useful raw material in industries, such as paints, paper, plastics, cosmetics, pharmaceuticals, and ceramics. Rheological properties and/or suspension stability of kaolinite are crucial factors in these products. The rheology and suspension of kaolinite has been studied intensively so far.1-8) Nakagaki M., et al. [3][4][5] provided evidences that the divalent cations exert stronger effect than monovalent cations on a reduced viscosity and Bingham yield value of the suspension. In an aqueous suspension of kaolinite, the -NH group of urea, hydrazine and formamide, and the -OH group of alcohols form the hydrogen bonding with an -SiO group on kaolinite surface to alter fluidity of a suspension. 10,11) In this situation divalent cations manifest stronger effect than monovalent ones on the Bingham yield value.3-6) The edge(ϩ)/face(Ϫ) inter-particle interactions promote aggregation and increase the viscosity of a suspension. On the other hand, adsorption of multivalent anions decreases charge density on the edge, diminishing edge(ϩ)/face(Ϫ) interparticle interaction, which results in reduction of the viscosity. 7)Johnson indicated that the kaolinite edge contains both silica-and alumina-like sites positively charged at low pH, but bears a negative charge at high pH. Kaolinite face contains by contrast only silica-like charge sites and remains negatively charged within a wide pH range. 12,13) Heath and Todros 14) derived both a Bingham yield value and viscosity of kaolin suspension as a function of pH and electrolyte concentration. Their results showed a minimum viscosity around pH 7 and they assumed that the isoelectric point of particle's edges was around pH 7. Adsorption of polyacrylic acid (PAA) on kaolinite particles affected flocculation/dispersion of a suspension solution. PAA proved a higher suspension stability at low or high concentration than at a medium concentration.1,2) The sodium salt of polyacrylic acid (Na-PAA) is adsorbed by alumina sites on the edge of kaolinite particles but not on the site of silica on basal plane of particles.15) The acid form of carboxylic acid of PAA can be adsorbed via hydrogen bonding between the carbonyl group of carboxylic acid and the hydroxyl group on a surface of the kaolinite basal plane.16) Gebhardt and Fuerstenau 17) measured the adsorption amount of PAA by silica. Conceicao et al. 18) probed influence of carboxymethylcellulose on rheological behavior of kaolinite suspension in the presence of ammonium polycarbonate as a dispersant. The presence of carboxymethylcellulose in kaolinite suspension conferred a shear thinning behavior, especially in the low shear rate range, followed by a trend to Newtonian fluid behavior. Na kagaki M., et al. 3,4) pointed out that polyvinylpyrrolidone (PVP) acts on kaolinite suspension as a flocculating agent at concentration lower than 2ϫ10 Ϫ3 %, but as a dispersing agent above that point. Yalcin et al. 19) studied the influence of surfactants (sodium or ammonium dodecyl sulfate, SDS or ADS) on flow behavior of ben...

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Flow behavior of coagulated colloidal sols. V. Dynamics of floc growth under shear

Cited by 65 publications

References 8 publications

Coagulation of suspensions in shear fields of different characters

Coagulation of suspensions in shear fields of different characters

Energy dissipation during stationary flow of suspensions of hydrophilic and hydrophobic glass spheres in organic liquids

Effect of Polyvinylpyrrolidone and Sodium Lauroyl Isethionate on Kaolinite Suspension in an Aqueous Phase

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