Chemical Engineering September 2023 - 6

cies of 90-95% and is very
prone to membrane fouling.
Now, an international team
of researchers has developed
a thin-film composite
(TFC) nanoporous membrane
(NPM) that is said to
improve the performance
of electrodialysis, achieving
separation efficiencies of
more than 99%, while consuming
less energy.
The new membrane and its
performance is described
in a recent issue of Nature
Water, with authors from the
Dept. of Chemical Engineering
at the University of Bath
(U.K.; www.bath.ac.uk),
along with colleagues from
China, South Korea, Singapore,
Australia and Belgium.
The new membrane system
uses TFC nanoporous
polyamide membranes as
anion-conducting membranes
to replace conventional
anionic exchange
membranes (AEMs). The
surface properties of the
TFC NPM are engineered
by co-deposition of polyethyleneimine
and polydopamine
(PDA), a compound
mussels excrete and use to
stick to rocks or wood in
wet conditions. This bioinspired
coating intensifies
the charge-shielding effect
to enable fast ion transfer,
and thus improve separation
with reduced fouling.
ORGANIC BATTERY
Last July, the world's first
operational Organic SolidFlow
Battery was delivered
to the hybrid wind and solar
park Schattendorf in the
Burgenland state of eastern
Austria. The battery
storage system was manufactured
by CMBlu Energy
Alzenau, Germany; www.
cmblu.com), and Burgenland
Energie is the hosting
electric utility.
Organic SolidFlow batteries
do not require critical raw
materials, such as lithium
or cobalt, nor do they use
metal ions. Instead, the system
uses an organic electrolyte
that combines both flow
and solid-state technology.
Built in early 2023, the
hybrid photovoltaic (PV)
park in Schattendorf has
(Continues on p. 8)
6
This electrolysis cell produces high-purity iron
P
rocessing iron ore is the most carbon-intensive
step in the steelmaking
process, often using coal as
an energy source. A new technology,
called Molten Oxide Electrolysis (MOE)
aims to decarbonize the iron-ore process
through electrification. " In the MOE cell, an
inert anode is immersed in an electrolyte
containing iron ore, and then it is electrified.
When the cell heats to 1,600°C, the
electrons split the bonds of the iron oxide
in the ore, producing pure liquid metal. No
CO2 or other harmful byproducts are generated
in this process, just oxygen, " explains
Adam Rauwerdink, senior vice president
of business development at Boston Metal
(Woburn, Ma.; www.bostonmetal.com), the
developer of the MOE process. The pure
metal produced in the MOE cell can be
directly integrated into conventional downBoston
Metals
stream-steelmaking processes.
Both the melting and the reduction steps
take place within the MOE cell (diagram).
High-density iron collects at the bottom
of the cell (at the cathode), while any impurities
remain in the less-dense electrolyte
phase, which floats above the heavier
metal phase. The high-purity metal can be
removed from the cell separately from the
impurity-containing electrolyte. Because
the impurities are separated within the
cell, MOE enables the use of lower-quality
feedstock than other avenues for steel decarbonization,
such as hydrogen-based
direct reduction, which requires very pure
feedstock and several processing steps.
" Lower-temperature, solid-state processes
like direct reduction do not involve melting,
so the impurities remain within the iron,
which must be removed using subsequent
melting and refining, " adds Rauwerdink.
The specialized inert anodes form the
centerpiece of the MOE cell. They not only
enable scalable ore processing with no CO2
emissions, but also support continuous operation.
" While high-temperature electrolysis
for high-volume metals production has been
demonstrated in the aluminum industry, we
are the first company to use the approach
for steel, " he notes. Boston Metal is currently
working to validate the inert anodes at
a semi-industrial scale, with plans in place to
pilot the technology with major steelmakers.
A new approach to refrigeration with
no global-warming potential
T
raditional vapor-compression refrigeration
relies on hydrofluorocarbons
(HFCs) as refrigerant fluids - a class
of compounds with global-warming
potentials (GWP) thousands of times higher
than that of CO2. A new approach from scientists
at Lawrence Berkeley National Laboratory
(LBL; Berkeley, Calif.; www.lbl.gov)
demonstrates cooling without the use of
high-GWP fluids using what the researchers
call the " ionocaloric " effect.
In ionocaloric cooling, ions mixing with
a solid material induce a phase transition
in the solid by lowering its freezing point,
similar to the freezing-point depression that
occurs when salt is used to melt road ice.
Cooling occurs because the lowering melting
point moves through the solid-to-liquid
phase transition temperature. " Ionocaloric
refers to a thermal response to an applied
ionic field, or electrochemical potential, "
explains Drew Lilley, co-founder of Calion
Technologies, a company formed to develop
the technology. Lilley's co-founder is
LBL scientist Ravi Prasher.
To elicit the cooling effect, the salt is mixed
with the solid form of the pure solvent ethylene
carbonate, which has a melting point
around 35°C. The temperature of the mix
decreases through the solid-to-liquid phase
transition of ethylene carbonate The temperature
decreases to 6.4°C with 23% NaI,
the researchers say, with heat absorption
occurring to convert the solid to liquid, thus
giving rise to a cooling effect.
The key to the technology, however, is
making the phase transition reversible. To do
that, the researchers apply a voltage to separate
the ions from the solvent through a membrane,
similar to what occurs in a battery or
fuel cell. Separating the ions from the solvent
raises its melting point again, and the ethylene
carbonate re-crystallizes, releasing heat.
The researchers have built one prototype
system, and are working on a larger-scale
prototype to refine the ion-solvent separation
step. " Our current focus is on improving
the engineering, " Lilley says. " We are really
looking to flesh out the potential of this kind
of cooling for a host of different applications. "
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
SEPTEMBER 2023
http://www.bath.ac.uk http://www.bostonmetal.com http://www.lbl.gov http://www.cmblu.com http://www.cmblu.com http://WWW.CHEMENGONLINE.COM
Chemical Engineering September 2023

Table of Contents for the Digital Edition of Chemical Engineering September 2023
