Determination of surface potential of hollow fiber membranes by streaming potential method

Achieving large zeta-potentials with charged porous surfaces

“…Several of our theoretical predictions could be tested by experiment. We have already mentioned the work of Donath and Pastushenko [24] who found a finite V ∞ at high salt, as well as the papers by Sobolev et al [30] and Lorenzetti et al [38] who reported the same trends as we predict here, but they used a very narrow range of c ∞ . The concentration must vary in the range described in Sec.…”

“…( 8), is fulfilled strictly in our examples, except concentrations that are very close to 10 −5 mol/L. [30,38].…”

“…Although the authors do not recognize this, their results simply imply that for permeable interfaces Z ≥ Ψ s (which is equivalent to A ≥ 1). More recent calculations also indicate that Z typically exceeds Ψ s [30,31]. Neither paper addresses itself to the issues of surface slip.…”

“…The asymptotic approximations are very well verified for large and small values of KH, both for a limit of vanishing ρ (Eqs. (30) and ( 34)) and for highly charged films (Eqs. ( 43) and ( 47)).…”

“…There have been experimental reports of a phenomenon of a finite electrokinetic mobility in concentrated solutions for various systems, including the cell surface coated with a layer of charged glycoproteins and glycolipids [24], 'hairy' polystyrene latexes [39], and more [40,41], but it has never been interpreted in this fashion. Sobolev et al [30] recently reported zetapotential measurements for a set of polyacrylonitrile hollow fiber membranes by varying c ∞ from 10 −4 to 10 −3 mol/L and concluded that ζ reduces with salt. Their experimental results, included in Fig.…”