Internal surface electric charge characterization of mesoporous silica

Abstract

Mesoporous silica is an emerging technology to solve problems of existing and to support projected revolutionary applications ranging from targeted drug delivery to artificial kidney. However, one of the major driving mechanisms, electric charging of internal mesoporous surfaces, has not been characterized yet. In the nanoscale confinements of mesoporous structures made of pore throats and pore voids, surface charges diverge from existing theoretical calculations and show local variation due to two occurrences. First, when the size of pore throat becomes comparable with the thickness of ionic layering forming on throats’ surfaces, ionic layers from opposite surfaces overlap so that ionic concentration on the surface becomes different than Boltzmann distribution predicts, and there will no longer be an equilibrium of zero electric potential at pore throat centers. Second, when this non zero potential inside throats becomes different than the potential of pore voids, ionic diffusion from void to throat creates axial ionic variation on surfaces. For such a case, we performed a pore level analysis on mesoporous internal surface charge at various porosities and ionic conditions. Pore parameters strongly affected the average internal charge which we characterized as a function of overlap ratio and porosity, first time in literature. Using this, a phenomenological model was developed as an extension of the existing theory to include nano-effects, to predict the average mesoporous internal surface charge as a function of EDL thickness, pore size and porosity.

Control of interfacial pH in mesoporous silica nanoparticles via surface functionalization

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Slip Effects on Ionic Current of Viscoelectric Electroviscous Flows through Different Length Nanofluidic Channels

“…The coupled behavior of the local ionic concentration in the electrolyte solution and the surface dissociation/association reactions creates the surface charge. This spontaneous phenomenon is commonly simulated by charge regulation models ,− in the literature. In the case of silica channel walls, the resulting surface charge can be evaluated through the following equations. K A and K B in eq are the equilibrium constants of surface reactions shown in eqs and .…”

Development of a schwarzite-based moving bed 3D printed water treatment system for nanoplastic remediation

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