Chemical Engineering July 2016 - 12

proof while still having very
good spring characteristics
- interesting for injection
nozzle diaphragms, casing
for consumer electronics,
or as dome tweeters for
speakers, says Heraeus.
" For fifty years, the commercial
success of amorphous
metals has been
held back by inadequate
manufacturing methods.
Now that changes, " says
Mattias Unosson, Exmet
co-founder and CEO.
new boriDes
Although borides are among
the hardest and most heatresistant
substances on the
planet, they oxidize at high
temperatures, leading to a
loss of the material's structural
integrity. Now researchers
from Drexel University
(Philadelphia, Pa.; www.
drexel.edu), Linköping University
(Sweden; www.liu.se)
and Imperial College London
(U.K.; www.ucl.ac.uk) have
produced an aluminum-layered
boride with unique behavior
at high temperatures.
To make the boride material
- molybdenum aluminum
boride (MoAlB) - the researchers
combined a molybdenum-boron
lattice with
a double layer of aluminum
to produce a material that
is durable enough to resist
oxidation at extremely high
temperatures. The key to this
remarkable characteristic is
the material's nanolaminated
structure with alternating layers
of molybdenum boride
and aluminum - a form the
Drexel group has established
a reputation for working with
since its creation of " MAX
phases " two decades ago.
The group also found that
the material retains its high
conductivity at elevated
temperatures. Its melting
point has yet to be determined,
but preliminary results
have shown it to be
greater than 1,400°C.
oxybroMination
The oxybromination of
methane into methyl bromide
typically generates
(Continues on p. 13)
12
A next-generation membrane bioreactor
Membrane
L
ast month at the IFAT
trade fair (May 30-June 3;
Munich, Germany), Huber
SE (Berching: www.huber.
de) and Microdyn-Nadir GmbH
(Wiesbaden, both Germany:
www.microdyn-nadir.de) unveiled
a rotating membrane bioreactor
(MBR) that utilizes membrane
laminate technology. " By combining
our two technologies we have created
a groundbreaking product symbiosis, " says
Walter Lamparter, CEO at Microdyn-Nadir.
In Huber's VRM (vacuum rotation membrane)
system (diagram, bottom), the membrane
modules are submerged into the activated
sludge and are mounted segmentally
onto air tubes. The trapezoidal membrane
segments are rotated through an air-induced
flushing stream driven by a filter drive. The
rising air bubbles are continuously cleaning
the membrane laminate sheets, thus significantly
reducing fouling and energy demand.
Instead of equipping the trapezoidal segments
with a Nadir flat-sheet membrane
welded onto a plate, as before, Huber is
now using the membrane laminate technology,
based on the Nadir flat-sheet membrane
made by Microdyn-Nadir. " By combining
our VRM technology with the unique
laminate technology, we achieve a significantly
higher packing density and therefore
an increase in membrane area per module.
Moreover, energy demand and costs can
be reduced tremendously, " says Oliver
Drainage layer
Rong, vice CEO at Huber.
Microdyn-Nadir's Bio-Cel membrane
laminate technology (diagram, top) is neither
a hollow fiber nor a plate, but rather
a hollow sheet. Unlike a plate-and-frame
construction, the Bio-Cel is backwashable
like a hollow-fiber module, and is said
to be the only module design that can
be cleaned mechanically. In addition, the
Bio-Cel membrane laminate technology
features a self-healing mechanism, which
allows the laminate to " heal " itself in less
than two minutes.
Recycling waste polystyrene into membranes
S
cientists from the National Chung
Hsing University (Taichung, Taiwan;
www.nchu.edu.tw), led by professor
Ming-Yen Wey, have successfully
developed an alternative route for recycling
plastic solid waste. They used waste polystyrene
to develop membranes suitable for
processes such as carbon capture, oxygen
enrichment and hydrogen purification.
They departed from three types of waste:
oriented polystyrene, expandable polystyrene
and high-impact polystyrene. The first
two are made solely from styrene monomer,
while high-impact polystyrene (HIPS) includes
butadiene to increase its strength.
Samples of waste polystyrene were
crushed, cleaned using ultrasonication with
water and ethanol, and dried overnight at
75°C. The scientists made the membranes
using a process called solution casting,
whereby polystyrene is dissolved in toluene,
and then the solutions are cast onto a glass
slide. These were then dried overnight at
75°C to evaporate the solvent, washed in
deionized water and dried again.
The decomposition temperatures of the
membranes are between 400 and 440°C,
and the presence of inorganic compounds
do not affect them.
Gas-permeability tests showed that expandable
polystyrene was the least effective
for gas separation due to instabilities in the
membrane structure. HIPS membranes were
slightly more stable and exhibited better
separation ability than the membranes made
from the other two types of polystyrene. According
to the scientists, this was due to the
butadiene molecules.
The scientists concluded that their novel
reuse route for polystyrene waste was economically
and environmentally friendly.
ChemiCal engineering www.Chemengonline.Com July 2016
http://www.huber http://www.microdyn-nadir.de http://www.drexel.edu http://www.liu.se http://www.ucl.ac.uk http://www.nchu.edu.tw http://www.Chemengonline.Com
Chemical Engineering July 2016

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