Flow dynamical characterization of sorbents immobilized as composites in membranes prepared by photochemical grafting onto polymers

Permeability measurements of water and n-hexane were carried out at 20°C through membranes prepared by photochemically grafting an epoxy-diacrylate copolymer or its composites onto cellulose. Composite membranes immobilizing 30.0 wt.% of calcite, seven calcium oxide samples obtained from calcination of calcite in different experimental conditions, α-iron(III) oxide and cobalt peroxide were thus tested. Hydraulic resistances as a function of membrane thickness were studied. Experimental results in the Poiseuille 's laminar flow regime are compatible with a normal Kozeny-Carman constant and a porosity of nominally 50%, indicating a regular packing of isometrically shaped particles in the microporous medium. Surface areas of membranes, both without additions and in the presence of filler materials, could thus be obtained by liquid permeametry measurements and successive treatment of data by the Kozeny-Carman equation. A general analysis of surface area characterization of immobilized sorbents is presented and compared with experimental values of B.E.T. method (liquid nitrogen adsorption). Results of flow dynamical investigation confirm the peculiar regularity of structure of the dense layer of photosynthetic membranes, as was found from morphology, from correlation between mean pore diameter and water fluxes per unit applied pressure drop, as well as from rejection characteristics in preceding studies.