Zeta Potentials and Yield Stresses of Silica Suspensions in Concentrated Monovalent Electrolytes: Isoelectric Point Shift and Additional Attraction

Franks, George V.

doi:10.1006/jcis.2002.8250

Cited by 269 publications

(263 citation statements)

References 39 publications

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“…2 Turbidity at k = 400 nm of CNC suspension for different CNC concentrations as a function of (a, left) salt concentration and of (b, right) ionic strength for divalent salts and monovalent salts, as indicated in the figure 2010; Vlachy et al 2009). Similar effects have been observed for other colloids such as bubbles (Craig et al 1993), silica nanoparticles (Franks 2002) as well as globular proteins (Boström et al 2003). Our results show a direct correspondence to the Hofmeister series where the surface affinity increases according to Li…”

Section: Ion Specific Effects For Monovalent Ionssupporting

confidence: 87%

Aggregation behavior of aqueous cellulose nanocrystals: the effect of inorganic salts

et al. 2016

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Natural anisotropic building-blocks such as cellulose nanocrystals (CNCs) have attracted considerable attention due to their biodegradability and nanometer-size. In this work the colloidal behavior of CNCs, obtained from sulfuric acid hydrolysis of microcrystalline cellulose, has been studied in presence of salts of different valences. The influence on the colloidal stability and nature of aggregates has been investigated for monovalent salts (LiCl, NaCl, KCl, CsCl), divalent salts (CaCl 2 and MgCl 2 ), and a trivalent salt (AlCl 3 ), both experimentally by means of turbidity and small angle X-ray scattering (SAXS) measurements, as well as by Monte Carlo simulations using a simple coarse-grained model. For the entire salt series, a critical aggregation concentration (CAC) could be determined by turbidity measurements, as a result of the reduction of effective Coulomb repulsions due to the presence of sulfate groups on the CNC surface. The CACs also followed the Schulze-Hardy law, i.e. the critical aggregation concentration decreased with increasing counterion valence. For the monovalent ions, the CACs followed the trend, which could be rationalized in terms of matching affinities between the cation and the sulfate groups present at the surface of CNCs. From the SAXS measurements it was shown that the density of the aggregates increased with increasing salt concentration and ion valence. In addition, these findings were rationalized by means of simulation, which showed a good correlation with experimental data. The combination of the experimental techniques and the simulations offered insight into interactionaggregation relationship of CNC suspensions, which is of importance for their structural design applications.Electronic supplementary material The online version of this article

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Section: Ion Specific Effects For Monovalent Ionssupporting

confidence: 87%

Aggregation behavior of aqueous cellulose nanocrystals: the effect of inorganic salts

et al. 2016

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“…3), it may be suggested that it is the larger charge of the larger particles that competes with the effect of steric hindrance. The higher particle charge may have two possible effects on the system, one being the adsorption of a higher load of potassium ions at the particle surface, as noted before [21], which would leave less cations free to act as electrostatic stabilizers in the junction gels and, thus, resulting in a weaker gel. A second possible effect relates to the higher repulsion between larger particles which would impede their physical approximation even at higher loads.…”

Section: Gelationmentioning

confidence: 91%

Rheological behavior of thermoreversible κ-carrageenan/nanosilica gels

Daniel‐da‐Silva

Pinto

Lopes‐da‐Silva

et al. 2008

Journal of Colloid and Interface Science

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“…The yield stress can be considered to be proportional to the inverse square of particle 224 separation (van der Waals forces) minus the square of the interaction potential (zeta potential) ( fly ash has been shown to be negative, with those in NaOH solutions showing a larger negative potential 234 (Nägele and Schneider 1989). This behavior is attributed to the enhanced adsorption of K + on the fly ash 235 particle surfaces than Na + ions (Franks 2002), resulting in a less negative surface charge as the K + 236 concentration is increased. As the zeta potential decreases (i.e., becomes less negative), the yield stress 237 increases due to a decreased repulsive force between fly ash particles.…”

Section: Rheological Behavior Of Fly Ash Suspensions Activated With Nmentioning

confidence: 99%

Observations on the rheological response of alkali activated fly ash suspensions: the role of activator type and concentration

et al. 2014

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5This paper reports the influence of activator type and concentration on the rheological properties of alkali 6 activated fly ash suspensions. A thorough investigation of the rheological influences (yield stress and 7 plastic viscosity) of several activator parameters, including: (i) the cation type and concentration of alkali 8 hydroxide, and (ii) the alkali-to-binder ratio (n) and silica modulus (Ms), and (iii) the volume of the 9 activation solution, on the suspension rheology is presented. The results indicate a strong dependence on 10 the cation and its concentration in the activation solution. The viscosity of the activation solution and the 11 volumetric solution-to-powder ratio are shown to most strongly influence the plastic viscosity of the 12 suspension. The suspension yield stress is predominantly influenced by the changes in fly ash particle 13 surface charge and the ionic species in the activator. A shift from non-Newtonian to Newtonian flow 14 behavior is noted in the case of silicate-based suspensions for Ms ≤ 1.5. This behavior, which is not 15 observed at higher MS values, or when the fly ash is dispersed in hydroxide solutions or pure water, is 16 hypothesized to be caused by colloidal siliceous species present in this system, or surface charge effects 17 on the fly ash particles. Comparisons of the rheological response of alkali activated suspensions to that of 18 portland cement-water suspensions are also reported. Page 2 NOMENCLATURE 22 n ratio of Na2O in the activator to the total fly ash content Ms ratio of SiO2-to-Na2O in the activator (as/p)v Activation solution-to-powder ratio, by volume (Refer to the definition of activation solution in 2.1 (as/b)v Activation solution-to-binder ratio, by volume; binder implying fly ash here (w/s)m Water-to-solids ratio, mass-based (Refer to the definition of solids in 2.1) w/c Water-to-cement ratio, mass-based, for OPC systems  Shear stress, Pa y Yield stress, Pa p Plastic viscosity, Pa.s a Apparent viscosity, Pa.s ̇ Shear rate, s -1 23Page 3 INTRODUCTION 24Ordinary portland cement (OPC) based concrete is one of the most widely used materials globally, and 25 production of OPC has been shown to require a significant quantity of energy and release significant 26 quantities of CO2. One of the sustainable alternatives to OPC that has been gaining attention is the use of 27 geopolymeric or alkali activated materials, where alumino-siliceous wastes/by-products such as fly ash or 28 slag can be activated using alkalis to create a binding medium that is X-ray amorphous and has a three-29 dimensional network structure (Palomo et al. 1999;Puertas and Fernández-Jiménez 2003; Škvára et al. 30 2009). The formation of the binding gel is a complex process including the dissolution process where Si 31and Al from the source materials are dissolved into a highly alkaline solution, precipitation of 32 aluminosilicate gel, and further polymerization and condensation to develop the final microstructure 33 (Davidovits 1999;Davidovits 2005). Geopolymeric...

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Zeta Potentials and Yield Stresses of Silica Suspensions in Concentrated Monovalent Electrolytes: Isoelectric Point Shift and Additional Attraction

Cited by 269 publications

References 39 publications

Aggregation behavior of aqueous cellulose nanocrystals: the effect of inorganic salts

Aggregation behavior of aqueous cellulose nanocrystals: the effect of inorganic salts

Rheological behavior of thermoreversible κ-carrageenan/nanosilica gels

Observations on the rheological response of alkali activated fly ash suspensions: the role of activator type and concentration

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