Mass transfer of weak acid in nanometer-sized pores of octadecylsilyl-silica gel

External and Intraparticle Diffusion of Coumarin 102 with Surfactant in the ODS-silica Gel/water System by Single Microparticle Injection and Confocal Fluorescence Microspectroscopy

“…In this case, Ke is defined as Ke = Cp/(εpCw), where εp is the porosity of the ODS-silica gel (0.69). 15 The Ke value agreed very well with Kk at [Triton X-100]w smaller than ~0.2 mmol dm -3 within the experimental errors. However, Ke was much less than Kk at [Triton X-100]w = 1 and 2 mmol dm -3 .…”

“…[14][15][16] In those reports, as the mass transfer rate in the microparticle/solution system was assumed to be limited by the intraparticle diffusion, the intraparticle diffusion coefficient (Dp) was estimated. When the supposed Dp value was independent of the microparticle diameter (d), the intraparticle diffusion was analyzed in detail on the basis of the pore and surface diffusion model.…”

“…When the supposed Dp value was independent of the microparticle diameter (d), the intraparticle diffusion was analyzed in detail on the basis of the pore and surface diffusion model. [14][15][16] For mass transfer of perylene as a water-insoluble organic compound in the presence of Triton X-100 (nonionic surfactant) in an ODS-silica gel/water system, however, the supposed Dp value depended on d, indicating that the mass transfer rate cannot be analyzed as the intraparticle diffusion. 17 From the d dependence of mass transfer rate, we concluded that the rate-determining step was the micelle-mediated solubilization of the dye at the microparticle surface.…”

Mass Transfer of Water-insoluble Organic Compound from Octadecylsilyl-silica Gel into Water in the Presence of a Nonionic Surfactant

“…In chromatography, solid phase extraction, drug delivery systems, and soil remediation, kinetic analyses of the sorption and release processes are important. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Surfactants are frequently used in porous material systems. For example, the dissolution of water-insoluble organic compounds from a soil or porous medium has been demonstrated on the basis of the characteristic behavior of surfactants.…”

“…3,8,10,17 In these systems, the rate-determining step of the sorption or release was the intraparticle diffusion, and the intraparticle diffusion could be discussed on the basis of the pore and surface diffusion model. In the present paper, we report the release of perylene as a water-insoluble organic compound from single ODS-silica gel microparticles into the water phase in the presence of polyoxyethylene (10) octylphenyl ether (Triton X-100).…”