Zdeněk Brož

Manometric techniques for determination of gas transport parameters in membranes. Application to the study of dense and asymmetric poly(vinyltrimethylsilane) membranes

Abstract An experimental manometric arrangement has been suggested for the study of membrane transport properties based on new techniques for the estimation of diffusion, sorption and permeation coefficients. Different variants of the transient regime and steady regime permeation of gases through polymer films have been proposed for the determination of membrane transport parameters. These techniques make possible measurements either from a steady initial condition or with variable boundary conditions. Transport parameters in quite different conditions (e.g., in the high pressure range, or in transitions between two steady permeation states) can be obtained from various permeation variables, with some advantages over the classical time-lag and modified time-lag methods. The methods have been applied to the study of transport properties of CO 2 , O 2 and N 2 in dense and asymmetric membranes made from poly(vinyltrimethylsilane). Transport parameters of different gases obtained for dense membranes are consistent with those found in some of the literature. The CO 2 permeabilities are found to depend on the pressures applied on the two sides of the membranes: the CO 2 permeability decreases in the case of dense membranes, but increases in the case of asymmetric membranes, with increase in the applied pressure.

Characterization of membrane skin defects by gas permeation method

Abstract This paper deals with a gas permeation method designed for the characterization of the skin layer of asymmetric or composite membranes. The suggested method enables the determination of the average skin thickness, the number of defects and their mean size. It was applied for the evaluation of the efficiency of a new process for skin defects removal. Measurements were performed using flat asymmetric polyvinyltrimethylsilane membranes prior to and after their in situ treatment.

A method for determination of gas diffusion and solubility coefficients in poly(vinyltrimethylsilane) using a personal computer

Abstract A new method has been developed for the determination of the diffusion and solubility coefficients of a gas in a polymer membrane. It is based on the measurement of time dependence of the total volume of the gas which has permeated the membrane. The collection and processing of experimental data as well as the gas permeation apparatus were controlled by a personal computer. The proposed method has been tested for a CO 2 -PVTMS [poly(vinyltrimethylsilane)] system. The results obtained were compared with the reported data.