Electrochemical technology for environmental treatment and clean
energy conversion*
F. C. Walsh
Electrochemical Engineering Group, Department of Chemical
Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK
Abstract: The applications of electrochemical technology in
environmental treatment, materials recycling, and clean synthesis are
briefly reviewed. The diversity of these applications is shown by the
number of industrial sectors involved. The scale of operation ranges
from microelectrodes to large industrial cell rooms. The features of
electrochemical processes are summarized.
Available and developing electrode designs are considered and illustrated
by examples including the regeneration of chromic acid electroplating
baths, metal ion removal by porous, 3-dimensional cathodes, rotating
cylinder electrodes (RCEs), and a reticulated vitreous carbon (RVC)
RCE. The use of performance indicators based on mass transport, electrode
area, and power consumption is emphasized.
Electrochemical reactors for energy conversion are considered, with
an emphasis on load-leveling and proton-exchange membrane (PEM) (hydrogenoxygen)
fuel cells. Ion-exchange membranes play an essential role in such reactors,
and the variation of electrical resistance vs. membrane thickness is
described for a series of extruded, Nafion® 1100 EW materials.
The characterization of high-surface-area, platinized Nafion surfaces
is also considered. The development of modular, filter-press cells as
redox flow cells in electrical load-leveling applications is concisely
described.
Trends in electrode, membrane, and reactor design are highlighted,
and the challenges for the development of improved reactors for environmental
treatment are noted.
* An issue of reviews and research papers based on
presentations made at the IUPAC/ICSU Workshop on
Electrochemistry and Interfacial Chemistry in Environmental Clean-up
and Green Chemical Processes, Coimbra, Portugal, 6-7 April, 2001.
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