Preparation of a novel polysulfone/polyethylene oxide/silicone rubber multilayer composite membrane for hydrogen-nitrogen separation

A novel poly sulfone/polyethylene oxide/silicone rubber (PSOPEO/SR) multilayer composite membrane was fabricated by double coating polysulfone substrate membrane with polyethylene oxide and silicone rubber. Gas permeation experiments were performed at 30 degrees C for hydrogen and nitrogen. PSf(PEO/SR membrane displayed high and steady performance for H-2/N-2: permeances of H-2 and N-2 of 49.51 and 0.601 GPU, respectively, and H-2/N-2 ideal separation factor of 82.3. It was explained that layer interfaces due to the introduction of PEO layer act as the permselective media and are responsible for the higher H-2/N-2 ideal separation factor which has exceeded the intrinsic permselectivities of the three polymers used in this study. (c) 2005 Elsevier B.V. All rights reserved.

A novel PTFE-reinforced multilayer self-humidifying composite membrane for PEM fuel cells

A novel polytetrafluoroethylene (PTFE)-reinforced multilayer self-humidifying composite membrane is developed. The membrane is composed of Nafion-impregnated porous PTFE composite as the central layer and nanosized SiO2 supported Pt catalyst imbedded into Nafion as the two side layers. The proton exchange membrane (PEM) fuel cells employing the self-humidifying membrane (20 mu m thick) under dry H-2/O-2 gave a peak power density of 0.95 W/cm(2) and an open-circuit voltage of 1.032 V. The good membrane performance is attributed to hygroscopic Pt-SiO2 catalyst at the two side layers, which results in enhanced anode side self-humidification function and decreased cathode polarization. (c) 2005 The Electrochemical Society.

Benzene electro-oxidation in a PEMFC for phenol and electricity cogeneration

In the present investigation, the electrochemically-assisted oxidation of benzene in a H-2-O-2 proton exchange membrane fuel cell (PEMFC) for electricity and phenol cogeneration is studied. Experiments were carried out in a PEMFC electrochemical reactor using Pd black as cathode electrocatalyst at 60 and 80 degrees C, respectively and 1 atm back pressure. Indeed, it was found that the only product detected under the examined experimental conditions was phenol. The online GC product analysis revealed that it is impossible to produce phenol when the fuel cell circuit is open (I = 0) under all the examined experimental conditions. When the fuel cell circuit was closed, however, the phenol yield was found to follow a volcano-type dependence on the cur-rent of the external circuit. It was found that the maximum phenol yield was 0.35% at 100 mA/cm(2) at 80 degrees C. At the same time, the PEMFC performance was also investigated during the phenol generation process. Furthermore, experiments with the rotating ring disc electrode (RRDE) technique showed that the intermediate oxidation product, i.e. H2O2 existed during the oxygen electro-reduction process. The cyclic voltammograms showed that benzene was strongly adsorbed on the Pd surface, leading to a degradation of the PEMFC performance. (c) 2005 Elsevier B.V. All rights reserved.

Separation of compounds interacting with liposome membrane in combined prescription of traditional Chinese medicines with immobilized liposome chromatography

Immobilized liposome chromatography (ILC), the stationary phase of which has been regarded as a mimic biomembranes system was used to separate and analyze compounds interacting with liposome membrane in Danggui Buxue decoction, a combined prescription of traditional Chinese medicines (CPTCMs), and its compositions Radix Astragli and Radix Angelica Sinensis. More than 10 main peaks in the extract of Danggui Buxue decoction were resolved on the ILC column, suggesting that more than 10 components in the prescription have significant retention on ILC column. Ligustilide, astragaloside, TV and formononetin, three main bioactive ingredients in Danggui Buxue decoction, were found to have relatively significant, while ferulic acid, another bioactive ingredient in the prescription, relatively weak retention on ILC column. Effects of the eluent pH and amount of immobilized phosphatidylcholine (PC) on separation of interactional compounds in the extract of Danggui Buxue decoction were also investigated. It was found that these two factors strongly affected the retention of some interactional compounds. In addition, the fractions partitioned with different solvents from water extract of this combined prescription were evaluated with this ILC column system. (c) 2005 Elsevier B.V. All rights reserved.