Determination of the zeta potential for highly charged colloidal suspensions

Giupponi, Giovanni; Pagonabarraga, Ignacio

doi:10.1098/rsta.2011.0024

Cited by 9 publications

(6 citation statements)

References 22 publications

(35 reference statements)

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“…However, one of the factors affecting the measurement of zeta potential is the viscosity of the medium. 49 Therefore, the presence of large anions close to the surface of GO can influence the obtained values even more in higher concentrations of salts. The interactions of cations with GO depend strongly on the deprotonation of carboxylic groups at higher pH values.…”

Section: ■ Introductionmentioning

confidence: 99%

Experimental and Molecular Dynamics Simulation Study of Specific Ion Effect on the Graphene Oxide Surface and Investigation of the Influence on Reactive Extraction of Model Dye Molecule at Water–Organic Interface

et al. 2016

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The influence of different inorganic anions (Cl − , Br − , SCN − , NO 3 − , SO 4 2−, and CH 3 COO − ) and cations (Ca 2+ , Mg 2+ , Na + , and NH 4 + ) on the surface potential of graphene oxide (GO) suspension has been investigated both experimentally and computationally. The hydrophilic GO surface has negative surface potential (zeta potential) which can be varied by changing the pH of the suspension as well as by adding external inorganic ions. The surface of GO is hydrophilic in a basic medium and becomes hydrophobic in an acidic medium because of the protonation and deprotonation of the surface functional groups. The presence of inorganic ions affects the electrophoretic mobility of the dispersed phase within the GO suspension and influences its zeta potential. This is due to the formation of a double layer of charge at the interface of the GO and ionic salt solution. Molecular dynamics simulations were used to understand the interactions of ions within the slipping plane of GO, which influences its zeta potential in salt solutions. The results suggested that the influence of the various inorganic ions on the electrokinetic potential of GO is ion-specific and depends on the polarizability of the ions. Having high specific surface area and being amphiphilic and biocompatible, GO was successfully utilized in the reactive extraction technique of methyl blue (MB) dye molecule at the water− toluene interface. The present study demonstrates that the presence of highly polarizable ions increases the zeta potential as well as hydrophobicity of GO, which facilitates the extraction of MB from the aqueous to the organic phase.

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Section: ■ Introductionmentioning

confidence: 99%

Experimental and Molecular Dynamics Simulation Study of Specific Ion Effect on the Graphene Oxide Surface and Investigation of the Influence on Reactive Extraction of Model Dye Molecule at Water–Organic Interface

et al. 2016

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“…The hydrodynamic forces exerted by the fluid on the suspended particles, together with the electrostatic and dispersion forces determine the motion of the macromolecules in the fluid [18]. The finite resolution of the colloidal particles on a lattice requires a proper calibration to identify the effective size where ζ is consistent with the colloidal charge [19]. The electrostatic potential drop around the colloids emerges consistently as a result of the ionic dynamics coupled to the fluid flow without further assumptions.…”

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confidence: 99%

Colloid Electrophoresis for Strong and Weak Ion Diffusivity

Giupponi

Pagonabarraga

2011

Phys. Rev. Lett.

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We study the electrophoretic flow of suspensions of charged colloids with a mesoscopic method that allows us to model generic experimental conditions. We show that for highly charged colloids their electrophoretic mobility increases significantly and displays a mobility maximum on increasing the colloidal charge for all salt concentrations. The electrophoretic mobility of highly charged colloids is also enhanced significantly when ion advection is dominant, leading to a strong heterogeneity in the local electrophoretic response especially at low-salt concentration, when ion diffuse layers overlap.

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“…The link-flux method employs the LBM for fluid dynamics and models ion motion in terms of fluxes between lattice cells. In [69] this method is compared to a LB-Poisson-Boltzmann approach for a fixed spherical particle in a periodic three-dimensional domain. The aim is to examine the influence of particle motion and counter-ion concentration on the ζ-potential, leading to the conclusion that for weakly perturbing electric fields or low Péclet numbers the equilibrium and dynamic ζ-potentials are indistinguishable.…”

Section: Related Workmentioning

confidence: 99%

A scalable multiphysics algorithm for massively parallel direct numerical simulations of electrophoretic motion

Bartuschat¹,

Rüde²

2018

Journal of Computational Science

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In this article we introduce a novel coupled algorithm for massively parallel direct numerical simulations of electrophoresis in microfluidic flows. This multiphysics algorithm employs an Eulerian description of fluid and ions, combined with a Lagrangian representation of moving charged particles. The fixed grid facilitates efficient solvers and the employed lattice Boltzmann method can efficiently handle complex geometries. Validation experiments with more than 70 000 time steps are presented, together with scaling experiments with over 4 · 10 6 particles and 1.96 · 10 11 grid cells for both hydrodynamics and electric potential. We achieve excellent performance and scaling on up to 65 536 cores of a current supercomputer.At the finest level of resolution, fluid, ions, and particles are simulated by Lagrangian approaches. These explicit solvent methods [37] typically apply coarse-grained molecular dynamics (MD) models to describe the motion of fluid molecules and incorporate Brownian motion [38]. The mesoscale dissipative particle dynamics method is applied in [39] to simulate electrophoresis of a polyelectrolyte in a nanochannel. Another explicit solvent method is presented in [40] for simulating DNA electrophoresis, modeling DNA as a polymer. In both methods the polymer is represented by bead-spring chains with beads represented by a truncated Lennard-Jones potential and connected by elastic spring potentials. Explicit solvent models, however, are computationally very expensive, especially for large numbers of fluid molecules due to pairwise interactions [40]. Moreover, the resolution of solvent, macromolecules, and ions on the same scale limits the maximal problem sizes that can be simulated [41]. Also the mapping of measurable properties from colloidal suspensions to these particle-based methods is problematic [37]. The high computational effort is significantly reduced in implicit particle-based methods that incorporate hydrodynamic interactions into the inter-particle forces. Such methods are applied in [37] and [42] to simulate electrophoretic deposition under consideration of Brownian motion and van der Waals forces. Nevertheless, these methods are restricted to few particle shapes and hydrodynamic interactions in Stokes flow.Euler-Lagrange methods constitute the intermediate level of resolution. These approaches employ Eulerian methods to simulate the fluid phase, whereas the motion of individual particles is described by Newtonian mechanics. For simulations of particles in steady-state motion, the resolved particles can be modeled as fixed while the moving fluid is modeled by an Eulerian approach. In [43] the finite volume method is applied to simulate electrophoresis of up to two stagnant toroids in a moving fluid, employing the Hückel approximation for a fixed ζ-potential and different electrical double layer thicknesses. The steady-state electrophoretic motion of particles with low surface potentials under a weak applied electric field in a charged cylindrical pore is simulated in [44] for a single c...

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Determination of the zeta potential for highly charged colloidal suspensions

Cited by 9 publications

References 22 publications

Experimental and Molecular Dynamics Simulation Study of Specific Ion Effect on the Graphene Oxide Surface and Investigation of the Influence on Reactive Extraction of Model Dye Molecule at Water–Organic Interface

Experimental and Molecular Dynamics Simulation Study of Specific Ion Effect on the Graphene Oxide Surface and Investigation of the Influence on Reactive Extraction of Model Dye Molecule at Water–Organic Interface

Colloid Electrophoresis for Strong and Weak Ion Diffusivity

A scalable multiphysics algorithm for massively parallel direct numerical simulations of electrophoretic motion

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