Chemical Engineering January 2022 - 5

Chementator
'Crystallized' hypochlorous acid brings enhanced
antimicrobial performance
A
new solid form of hypochlorous
acid (HOCl) is showing promise as a
highly effective antimicrobial agent.
PCT Ltd. (Little River, S.C.; www.
para-con.com) and Onza Corp. (Denver,
Colo.; www.onzacorp.com) achieved what
is said to be the industry's first-ever successful
" crystallization " of HOCl and rehydration
back into liquid HOCl, while maintaining all
the chemical properties of the original HOCl.
" We entrapped hypochlorous acid between
the crystal boundaries and fluid inclusions in
an erythritol-based matrix using Stevia in this
first test, " explains Paul Mendell, co-founder
of Onza. Onza's proprietary gas-trapping
technology enables much easier transport
and application of chemical products,
since they can be stored as a dry, stable
solid rather than in their gaseous form, effectively
extending products' useful life and
application range. Onza is also working on
gas-entrainment
technologies for ozone,
nitric oxide, chlorine dioxide and hydrogen
sulfide. The crystals were manufactured at
Noble Analytical Laboratory in Pampa, Texas
by Victoria McDowell.
After about a week of exposure to air at
room temperatures, the team tested the
HOCl crystals against non-pathogenic E.
coli on a stainless-steel surface at an independent
laboratory, and the test revealed
antimicrobial activity greater than the control
Edited by:
Gerald Ondrey
CO2 SEPARATION
Conventional DDR-type
zeolite membranes are
well suited for separating
CO2 from differentsized
molecules, such as
methane, which is present
in associated gas or
natural
gas.
However,
such membranes are not
very efficient for separating
CO2 from O2 or
N2, which is common in
many industrial exhaustgas
streams. Now, a
new
DDR-type
zeolite
PCT
(using Stevia alone) - resulting in a 95% reduction
in the E. coli colony.
" While this first test proved antimicrobial
activity, we plan to improve efficacy. The goal
will be to expand the application of hypochlorous
acid (and other disinfectants), by
offering new, alternative delivery forms and
hopefully greater stabilization of otherwise
sensitive or unstable compounds, " adds
Mendell. Future work will involve analyzing
different crystal structures and compositions,
and conducting efficacy studies with the U.S.
Environmental Protection Agency (EPA).
Layered catalyst selectively generates
two-carbon compounds from CO2
C
opper-catalyzed electrochemical
reduction offers a path for making
valuable chemicals, such as ethanol
or ethylene, from CO2. However,
selectively generating sufficient yields
of two-carbon products requires precise
manipulation of the microenvironment near
the surface to control reaction activity and
product selectivity.
Recent research from the Lawrence
Berkeley National Laboratory (LBL; Berkeley,
Calif.; www.lbl.gov) has demonstrated
progress toward a catalyst system capable
of activity and selectivity for C2 products
that vastly outstrips those of copper alone.
The LBL approach relies on layering two
ion-conducting polymers - one a perfluorosulfonic
acid, cation-conducting ionomer
(Nafion); the other a polystyrene-based,
anion-conducting ionomer (Sustainion) -
onto a copper surface to catalyze the electrochemical
reduction.
" The Sustainion layer boosts the concentration
of CO2 relative to that of H2O
at the catalyst surface because the CO2
affinity and hydrophobicity of this ionomer,
make it more likely that carbon-carbon
coupling will occur, " explains Alexis Bell,
senior scientist at LBL and professor of
chemical engineering at the University of
California at Berkeley (www.berkeley.edu).
" Meanwhile, the Nafion raises pH near the
copper surface by trapping hydroxyl ions,
thereby suppressing the formation of H2
and C1 products. "
Further enhancement of the surface effects
of the bilayer ionomer films is achieved
by altering the cathode voltage by applying
five-second pulses, generating Faraday efficiencies
of over 90% for C2 products, and
only 4% for hydrogen formation.
In the future, Bell and his team plan to investigate
methods to coat copper nanoparticles
with the bilayer ionomers. The concept
of layering ionomers can also be
applied to other catalyst systems.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
JANUARY 2022
membrane, developed
by NGK Insulators, Ltd.
(Tokyo, Japan; www.
ngk-insulators.com) has
been demonstrated to be
five times more efficient
than conventional DDRtype
zeolite membranes
for separating CO2 from
such exhaust gases.
Unlike conventional
zeolite membranes that
perform the separation
on the difference in
molecule's size, the new
membrane makes use of
the different adsorption
characteristics (affinity)
for molecules to separate
CO2 from N2 and O2. Taking
advantage of the stable
properties of ceramics
under harsh conditions,
the company is working
to increase the separation
factor even further for applications
involving hightemperature
industrial
exhaust gases. Following
more testing and development,
the company is
targeting a commercial
launch in 2030.
GAS SWEETENING
TechnipFMC plc (Newcastle
Upon Tyne, U.K.;
www.technipfmc.com)
and Petronas Technology
Ventures Sdn Bhd
(PTVSB), a subsidiary of
Petronas (Kuala Lumpur,
Malaysia; www.petronas.
com),
recently
entered
into an agreement to
commercialize a unique
natural-gas processing
membrane that reduces
(Continues on p. 6)
5
https://www.para-con.com/ https://onzacorp.com/ https://www.ngk-insulators.com/en/ https://www.ngk-insulators.com/en/ https://www.berkeley.edu/ https://www.lbl.gov/ https://www.technipfmc.com/ https://www.petronas.com/ https://www.petronas.com/ http://WWW.CHEMENGONLINE.COM
Chemical Engineering January 2022

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