Approximate analytic expressions for the electrophoretic mobility of spherical soft particles

Ohshima, Hiroyuki

doi:10.1002/elps.202000339

Cited by 7 publications

(4 citation statements)

References 34 publications

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“…In short, the soft particle theory is based on the Poisson–Boltzmann equation for the electric potential distribution, the Navier–Stokes equation for the liquid flow, and a Debye–Bueche model for the polyelectrolyte layer contribution. , General expressions can be written from the soft particle theory to predict electrophoretic mobility, but they can only be solved numerically. However, within given sets of approximations, analytic solutions can be derived and applied in many relevant cases. ,− …”

Section: Introductionmentioning

confidence: 99%

Microalgae as Soft Permeable Particles

et al. 2022

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The colloidal stability of non-motile algal cells in water drives their distribution in space. An accurate description of the interfacial properties of microalgae is therefore critical to understand how microalgae concentrations can change in their biotope or during harvesting processes. Here, we probe the surface charges of three unicellular algae�Chlorella vulgaris, Nannochloropsis oculata, and Tetraselmis suecica�through their electrophoretic mobility. Ohshima's soft particle theory describes the electrokinetic properties of particles covered by a permeable polyelectrolyte layer, a usual case for biological particles. The results appear to fit the predictions of Ohshima's theory, proving that all three microalgae behave electrokinetically as soft particles. This allowed us to estimate two characteristic parameters of the polyelectrolyte external layer of microalgae: the volume charge density and the hydrodynamic penetration length. Results were compared with transmission electron microscopy observations of the algal cells' surfaces, and in particular of their extracellular polymeric layer, which was identified with the permeable shell evidenced by electrophoretic measurements. Noticeably, the algal surface potentials estimated from electrophoretic mobility using the soft particle theory are less negative than the apparent zeta potentials. This finding indicates that electrostatics are expected to play a minor role in phenomena of environmental and industrial importance, such as microalgae aggregation or adhesion.

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Section: Introductionmentioning

confidence: 99%

Microalgae as Soft Permeable Particles

et al. 2022

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“…The mobility expression involves the exponential integrals (specifically μ d ), and thus it is not very convenient to use for practical applications. Here we derive an alternative approximate expression for electrophoretic mobility using the simplified technique introduced by Ohshima. ,, Below we will discuss the detailed steps to derive the approximate form of expression ).…”

Section: Resultsmentioning

confidence: 99%

Gel Electrophoresis of a Hydrophobic Liquid Droplet with an Equipotential Slip Surface

et al. 2022

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A theoretical study has been carried out on the electrophoresis of charged dielectric liquid droplets with an equipotential and hydrodynamically slipping surface moving in a quenched polymeric charged hydrogel medium. The liquid inside the droplet is electrically neutral. The Brinkman–Debye–Bueche model is employed to study the gel electrophoresis of such a hydrophobic and equipotential liquid droplet considering the long-range hydrodynamic interaction between a migrating droplet and the gel skeleton. Within the weak field and Debye–Hückel electrostatic framework, we derive an original closed-form expression for electrophoretic mobility, which further recovers the existing mobility expressions derived under several limiting conditions. The derived expressions for electrophoretic mobility explicitly involve exponential integrals, which are not so convenient for practical applications. Thus, the exact forms of the electrophoretic mobility under various electrohydrodynamic conditions are further approximated to make them free from exponential integrals. The approximate forms are found to be in excellent agreement with the exact results with maximum relative errors of about 1.5%.

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“…Approximate solutions, such as those by Ohshima, Healy, and White (OHW, Eq. S8) [61] and by Ohshima (Eq. S9) [62], cover the whole range of possible ka values.…”

Section: Analogous Electrokinetic Potentials Between Nanoparticles An...mentioning

confidence: 98%

Assessment of nanoparticle immersion depth at liquid interfaces from chemically equivalent macroscopic surfaces

Smits

Giri

Shen

et al. 2022

Journal of Colloid and Interface Science

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Approximate analytic expressions for the electrophoretic mobility of spherical soft particles

Cited by 7 publications

References 34 publications

Microalgae as Soft Permeable Particles

Microalgae as Soft Permeable Particles

Gel Electrophoresis of a Hydrophobic Liquid Droplet with an Equipotential Slip Surface

Assessment of nanoparticle immersion depth at liquid interfaces from chemically equivalent macroscopic surfaces

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