Search

In our previous work, we demonstrated ion selective transport through a single membrane. In this study, we adopted a new method by using a dual membrane system to improve the performance. Two gold-sputtered membranes were mounted between two independent glass cells. Then, polypyrrole (PPy) was electrochemically deposited on the gold side of each membrane. Benzylamine (BA) and Methylene blue (MB) were used as the probe materials in this membrane system. Since the PPy serves as a separator and an electrode, an electric field could be applied between the two membranes directly. Furthermore, a high electric field could be obtained between the two membranes even at a low applied potential because the distance between the two membranes is in microunits. As a result, the dual membrane system exhibited improved control and selectivity for the ions. Finally, the different transport mechanism for BA and MB was discussed in detail. [ABSTRACT FROM AUTHOR]

A number of ion separation methods successfully separate ions by controlling the ion's transport. In general, transport rate of ions depends on their charge, size or hydrated radii. However, methylene blue (MB) used in this study showed different transport tendency compared to other ions. The results indicate that the transport of MB is affected by its adsorption property. Thus, we tried to elucidate the special transport mechanism of MB in detail. The conducting polymer modified membrane used in this study was prepared by the electrochemical polymerization of pyrrole on a gold-sputtered polycarbonate (PC) membrane in aqueous solution. Characterization of the polypyrrole (PPy) modified membrane was performed by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDX). The transport of MB through the PPy membrane was controlled by applied potentials. The concentration change of MB in permeated cell was detected by high performance liquid chromatography (HPLC) equipped with a UV-Vis detector. [ABSTRACT FROM AUTHOR]

Highly porous off-stoichiometric tungsten trioxide (WO 3-σ ) with hollow and yolk-shell structures have been successfully synthesized via a selective leaching strategy, following hydrogenation using PbWO 4 spheres as the starting material. It was found that the yolk-shell WO 3-σ could be obtained from hollow WO 3-σ by dividing the continuous leaching process into two intervallic processes. The unique structural features and high conductivity facilitate both ion and electron transport, greatly enhancing reversible lithium storage capacity. In comparisons of the hollow WO 3-σ and yolk-shell WO 3-σ , the yolk-shell structure exhibited more long-term stability due to extra spatial elasticity. [ABSTRACT FROM AUTHOR]