Pore size effects on surface charges and interfacial electrostatics of mesoporous silicas

Abstract

Water in confinement becomes more structured than bulk water, and its properties, such as the dielectric constant, change. It remains unclear, however, how the interfacial reactions in confinement, such as...

RETRACTED: Capacitive Behavior of Aqueous Electrical Double Layer Based on Dipole Dimer Water Model

“…Considering that very small electrode pores are being under consideration and the electric dipole is not considered in the calculations of Figure 3 b,c, the relative dielectric constant in the pore is set as and in the bulk it is still set as . The molecular dynamics simulations show that the perpendicular component of the water dielectric constant drastically decreases in narrow pores [ 82 , 83 ] compared with the bulk water dielectric constant; so, we choose a small value for the dielectric constant of water in the pore. From the information provided in Figure 3 , we can produce four analyses.…”

Adsorption of cesium and strontium on mesoporous silicas

“…Their pore sizes, specific surface areas, and surface hydroxyl group densities have been reported elsewhere, as listed in Table S1 in the ESI. † 24 Each mesoporous silica will be denoted by an acronym combining ''M'' or ''S'' (the first letters of MCM-41 or SBA-15) with the corresponding mesopore diameter shown in Table S1 (ESI †). As in a previous study, mesoporous silicas were pretreated with washing and drying.…”

“…As in a previous study, mesoporous silicas were pretreated with washing and drying. 24 Milli-Q s grade pure water and analytical-grade chemicals purchased from Wako Pure Chemical Industries were used to prepare the solutions for the adsorption experiments. Unless noted otherwise, all batch experiments were conducted in ambient atmosphere at room temperature (20-25 1C), and the containers were continuously agitated with a shaker.…”

“…Both G Cs and G Sr increased with increasing pH, corresponding to the fact that the surface charge densities of mesoporous silica increase with pH. 24 Conversely, G Cs and G Sr decreased with increasing ionic strength. This suggests that the adsorption of Cs + and Sr 2+ are inhibited by direct competition with Na + and/or the enhanced screening of the negative surface charge and implies that Cs + and Sr 2+ are electrostatically adsorbed on the surface hydroxyl groups of the mesoporous silicas, i.e., they form outer-sphere complexes.…”

“…The surface charge density of mesoporous silicas decreases with decreasing pore size because of the overlap of the electrical double layers (EDLs) inside the pore and a decrease in the relative permittivity of water near the interface. 24 Some reports have focused on individual metal ions and investigated the peculiarities of adsorption reactions in small spaces. 25 The pore size effects on adsorption reactions, however, a Regulatory Standard and Research Department, Secretariat of Nuclear Regulation lack a unified picture and differ among reports.…”