A New Method for the Characterization Of Porous Materials

Abstract

A simple new method of characterization of porous materials is developed in this paper. In this method, we combine the traditional Kelvin equation with an improved statistical adsorbed film thickness to account for the finite dimension of pores. The adsorption process in a pore is viewed as a molecular layering process followed by a filling mechanism. Here, we argue that this mechanism is valid not just for mesopores but also micropores because of our allowance for the statistical film thickness to be a function of not only pressure but pore size as well. The model is tested against the data of nitrogen adsorption onto activated carbon samples: the fitting is found to be excellent, and the results are comparable with those obtained by other methods such as the DFT method. The much shorter computation time required by this method compared to that by DFT makes this method a very attractive alternative in the PSD characterization.

Behaviour of pure water and water mixture with benzene or chloroform adsorbed onto ordered mesoporous silicas

“…The dependence of this effect on the used pressure range results in different dependences of the S BET values on the high boundary value p/p 0,max for the studied silicas (Fig. 2) Pore size distributions (PSD, f V (R) and f S (R) with respect to the pore volume and the specific surface area respectively) were calculated using an overall isotherm equation based on the equation proposed by Nguyen and Do for carbon adsorbents with slitlike pores [40] and modified for cylindrical pores and voids between spherical particles [41,42]. This equation was solved by means of a regularization procedure based on the CONTIN algorithm [33] as described elsewhere [41].…”

Fumed Silicas Possessing Different Morphology and Hydrophilicity

“…The pore size distribution f (R p ) was computed by using the overall isotherm equation (12) with the modified Kelvin equation rewritten with consideration for pores as gaps between spherical primary particles in aggregates (9b) and the regularization procedure (13,14) under nonnegativity conditions with a fixed regularization parameter α = 0.01. The distributions of free-energy changes ( G) upon water adsorption on the silica surfaces from air were calculated by using the Langmuir equation (9) as the kernel in the overall adsorption isotherm in the form of Fredholm integral equation of the first kind (13,14).…”

Silver and Gold Nanoparticles on Sol-Gel TiO2, ZrO2, SiO2 Surfaces: Optical Spectra, Photocatalytic Activity, Bactericide Properties

“…These results indicate that the silver nanoparticles formed on TiO 2 under given experimental conditions (UV irradiation, ambient atmosphere, room temperature) are chemically very reactive and were easily oxidized with Ag 2 O shell formation. Authors (Nguyen, 1999) reported that the grows of silver oxide overlayer up to 6 nm on Ag o -TiO 2 interface is a function of plasma exposure time at room temperature. Higher intensity of oxide peak for TiO 2 /ZnO/Ag film as compared to TiO 2 /Ag supports our assumption about more homogeneous distribution of smaller Ag nanoparticles on this surface.…”