Inorganic ion exchange membranes consisting of microcrystals of zirconium phosphate supported by Kynar®

Hybrid materials science: a promised land for the integrative design of multifunctional materials

For more than 5000 years, organic-inorganic composite materials created by men via skill and serendipity have been part of human culture and customs. The concept of "hybrid organic-inorganic" nanocomposites exploded in the second half of the 20th century with the expansion of the so-called "chimie douce" which led to many collaborations between a large set of chemists, physicists and biologists. Consequently, the scientific melting pot of these very different scientific communities created a new pluridisciplinary school of thought. Today, the tremendous effort of basic research performed in the last twenty years allows tailor-made multifunctional hybrid materials with perfect control over composition, structure and shape. Some of these hybrid materials have already entered the industrial market. Many tailor-made multiscale hybrids are increasingly impacting numerous fields of applications: optics, catalysis, energy, environment, nanomedicine, etc. In the present feature article, we emphasize several fundamental and applied aspects of the hybrid materials field: bioreplication, mesostructured thin films, Lego-like chemistry designed hybrid nanocomposites, and advanced hybrid materials for energy. Finally, a few commercial applications of hybrid materials will be presented.

Polysulfone-based Ionomers for Fuel Cell Applications

This paper is a review that is focused on ionomers based on aromatic polysulfone backbone and intended to be used in proton exchange membrane fuel cells or in direct methanol fuel cells. Emphasis is placed on the different chemical routes to prepare the ionomers. Special attention is given to the impact of the ionomer structure on the conductivity performance and on the dimensional stability of the membranes at high temperatures.

On the electrochemical characterization of ion-selective cellulose acetate membranes with and without stigmasterol liquid membranes

Stigmasterol, a plant product, has been used as a surfactant to generate liquid membranes supported on a cellulose acetate matrix. Electrochemical characterization of the membrane has been attempted with a view to simulating its behavior with natural membranes by measuring membrane potentials and membrane conductance. The selectivity of cellulose acetate membrane kept in contact with magnesium chloride solutions of different mean concentrations has been found to change from anion to cation. Transport numbers have been estimated from membrane potential data. Permselectivity and fixed charge density values for the cellulose acetate membrane with and without stigmasterol have been determined from transport numbers. The variation of these parameters with concentration and pH has also been examined.

Transport of Th(IV) and U(VI) through barium silico-phosphate composite membrane using electric field

The present paper describes the preparation of a novel barium silico-phosphate filter paper supported membrane. It is based on precipitation reaction of barium silico-phosphate on the outer surface and in the interstices of a filter paper by means of electrodialysis. The main physical and electrical properties of the membrane are given and its electrodialysis behaviour is assessed for Th(IV) and U(VI). The transport of Th(IV) in presence of U(VI) was studied. The cationic fluxes of Th(IV) and U(VI) were found to be 1.2 × 10−8 and 6.5 × 10−9 g eq cm−2 s−1, respectively. Transport of Th(IV) and U(VI) in presence of EDTA was investigated. The cationic flux of U(VI) is found to be 9.8 × 10−9 g eq cm−2 s−1 at a current density of 25 mA/cm2. A comparative study on the electro osmotic effect was carried out using the developed membrane and commercially available Nafion membranes. In this context, different parameters like current density, electrolyte concentration, etc. were investigated. The electro-osmotic permeability coefficient, D e, of Th(IV) through barium silico-phosphate and Nafion membranes were 6.9 × 10−2 and 1.0 × 10−2 cm3/A s, respectively. It can be concluded that inorganic membranes have very marked electro-osmotic properties unlike their organic counterparts.