Colloidal Charge Determination in Concentrated Liquid Dispersions Using Torsional Resonance Oscillation

Bergenholtz, Johan; Willenbacher, Norbert; Wagner, Norman J.; Morrison, Bradley R.; Ende, Dirk van den; Mellema, J.

doi:10.1006/jcis.1998.5463

Cited by 45 publications

(58 citation statements)

References 63 publications

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“…While this short-time quantity has been rather routinely determined for micron-sized charge-stabilized colloids [16,62], a direct mechanical measurement of η ∞ for BSA solutions is difficult, since the required frequencies ω ≫ τ…”

Section: High-frequency Viscositymentioning

confidence: 99%

Viscosity and diffusion: crowding and salt effects in protein solutions

et al. 2012

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We report on a joint experimental-theoretical study of collective diffusion in, and static shear viscosity of solutions of bovine serum albumin (BSA) proteins, focusing on the dependence on protein and salt concentration. Data obtained from dynamic light scattering and rheometric measurements are compared to theoretical calculations based on an analytically treatable spheroid model of BSA with isotropic screened Coulomb plus hard-sphere interactions. The only input to the dynamics calculations is the static structure factor obtained from a consistent theoretical fit to a concentration series of small-angle X-ray scattering (SAXS) data. This fit is based on an integral equation scheme that combines high accuracy with low computational cost. All experimentally probed dynamic and static properties are reproduced theoretically with an at least semi-quantitative accuracy. For lower protein concentration and low salinity, both theory and experiment show a maximum in the reduced viscosity, caused by the electrostatic repulsion of proteins. The validity range of a generalized Stokes-Einstein (GSE) relation connecting viscosity, collective diffusion coefficient, and osmotic compressibility, proposed by Kholodenko and Douglas [PRE, 1995[PRE, , 51, 1081 is examined. Significant violation of the GSE relation is found, both in experimental data and in theoretical models, in semi-dilute systems at physiological salinity, and under low-salt conditions for arbitrary protein concentrations.

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Section: High-frequency Viscositymentioning

confidence: 99%

Viscosity and diffusion: crowding and salt effects in protein solutions

et al. 2012

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“…Torsional resonance oscillation was applied at four distinct frequencies ( (52,120,198 and 364)10 3 rad/s), for which the criterion for high frequency regime is fulfilled, i.e. the applied shear field is much faster than the Brownian motion of colloidal particles [81] the characteristic small displacement mobility of a particle which decreases with increasing particle concentration).…”

Section: Identification Of the Stabilization Mechanism With High Freqmentioning

confidence: 99%

Clogging of microchannels by nano-particles due to hetero-coagulation in elongational flow

Georgieva

Dijkstra

Fricke

et al. 2010

Journal of Colloid and Interface Science

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We have investigated the phenomenon of flow-induced aggregation in highly concentrated colloidal dispersions exposed to strongly converging flow fields. This phenomenon is relevant not only for classical technical operations like coating, pumping or filtration, but also for the application of concentrated suspensions in upcoming processing technologies based on microfluidic devices. A ring-slit device (gap height 10 micrometers to 25 micrometers), which allows for a variation of flow kinematics in a wide range, has been developed in order to investigate this phenomenon. Various polymer dispersions with different particle surface properties have been used as model systems. Our experiments exclude, that channel clogging is due to retention of pre-existing aggregates, fouling or hydrodynamic bridging. Instead, we demonstrate that clogging of the microchannel is induced by hetero-coagulation between primary colloidal particles and micron-sized impurities present at concentrations on the order of 100 ppm to 1000 ppm. Clogging can occur even if the diameter of these impurities is less than a tenth of the gap height. Aggregation takes place in the converging flow field at the channel entrance, but not in the shear field within the slit. It can be suppressed by appropriate stabilization of the primary particles

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“…We are not aware of any closed analytical expressions for Z 1 (f)/Z 0 of charged spheres with stronger screening of the electrostatic double layer repulsions. The few measurements available 22,33,34 suggest, however, that…”

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confidence: 99%

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

et al. 2002

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According to the Stokes-Einstein-Debye (SED) relation, the rotational diffusion coefficient of a colloidal tracer sphere scales with the inverse of the solvent viscosity. Here we investigate the generalization of the SED relation to tracer diffusion in suspensions of neutral and charged colloidal host spheres. Rotational diffusion coefficients are measured with dynamic light scattering and phosphorescence spectroscopy, and calculated including two-and three-particle hydrodynamic interactions. We find that rotational tracer diffusion is always faster than predicted by the SED relation, except for large tracer/host size ratios l. In the case of neutral particles this observation is rationalized by introducing an apparent l-dependent slip boundary coefficient. For charged spheres at low ionic strength, large deviations from SED scaling are found due to the strongly hindered host sphere dynamics. Finally, we present some first experiments on tracer sphere diffusion in suspensions of host rods, showing that hydrodynamic hindrance by rods is much stronger than by spheres. We conclude by pointing to some interesting unresolved issues for future research. I IntroductionThe rotational diffusion coefficient of a single colloidal sphere with radius a T suspended in a solvent with shear viscosity Z 0 is given by the familiar Stokes-Einstein-Debye (SED) relationwith k B T the thermal energy and f r 0 the Stokesian friction factor. Eqn. (1) assumes that the particle is large enough for the solvent to behave as a structureless continuum with vanishing response time. Moreover, stick boundary conditions are assumed, i.e. the velocity of the fluid on the tracer surface equals that of the tracer. Eqn. (1) holds quantitatively not only for colloidal particles but,

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Colloidal Charge Determination in Concentrated Liquid Dispersions Using Torsional Resonance Oscillation

Cited by 45 publications

References 63 publications

Viscosity and diffusion: crowding and salt effects in protein solutions

Viscosity and diffusion: crowding and salt effects in protein solutions

Clogging of microchannels by nano-particles due to hetero-coagulation in elongational flow

On the validity of Stokes–Einstein–Debye relations for rotational diffusion in colloidal suspensions

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