Chemical Engineering March 2019 - 8

arrangement in the phosphorus
layers, in contrast to other
layered or flat materials, provides
ideal sites for nitrogen
adsorption and the electronic
structure at the edges was
best suited for binding, activating
and reducing nitrogen
by a low-energy pathway.
The team included the catalyst
nanosheets in a carbonfiber
electrode for electrolysis.
To provide a nitrogen supply, a
hydrochloride electrolyte solution
was saturated with nitrogen.
On application of a voltage,
the electrode readily and
selectively produced ammonia
from nitrogen. Wang says the
layered black phosphorus
even outperformed most
nonmetallic and metal-based
catalysts lately reported.
A drawback of black phosphorus
is that its performance
declines in the long term due
to oxidation, so it will be necessary
to find ways of preventing
degradation in the electrolyte,
says the team.
BIO-BASED MEG
Braskem (São Paulo, Brazil;
www.braskem.co/br) and Haldor
Topsoe S/A (Lyngby, Denmark;
www.topsoe.com) have
reached mechanical completion
of the MOnoSAccharide
IndustrIal Cracker (Mosaik)
process step of their demonstration
plant that will produce
bio-based monoethylene glycol
(MEG) from sugars. Mosaik
is a method for cracking
sugars into an intermediary
product, which can be further
converted to MEG or other
biochemicals, such as methyl
vinyl glycolate or glycolic acid,
using Topsoe's patented processes
and catalysts.
The demonstration plant,
located in Lyngby, Denmark,
is an important step to upscale
the Mosaik process and
begin production at an industrial
scale, which is planned
to commence in 2023. The
plant can produce more than
100 ton/yr of glycolaldehyde,
which is converted into MEG
in the next process step.
DAIRY BIOREFINERY
Whey permeate (WP) and delactosed
whey permeate (DLP)
(Continues on p. 10)
8
A single process to handle hydraulic fracturing
produced water and offgases
T
wo major concerns in
hydraulic fracturing operations
are finding efficient
ways to handle
the massive amount of produced
wastewater, and dealing
with offgases from the well.
A new technology developed
by Ship & Shore Environmental
Inc. (Signal Hill, Calif.; www.
shipandshore.com),
in
partnership
with Hydrozonix LLC
(Conroe, Tex.; www.hydrozonix.
com), employs an enclosed flare
to destroy the well offgases and
harvests the resulting energy to
evaporate wastewater. According
to Mike Pawlowski, senior
technical sales manager at Ship & Shore Environmental,
this the first technology available
to the hydraulic fracturing market for onsite
evaporation of produced water. The process
- called Hydroflare - works by connecting
the source of well offgases to an enclosed
flare burner. " The resultant heat from the flare
is passed to a tower or stack, which includes
spray nozzles to mist the produced water into
the high-temperature discharge of the burner
section, " explains Pawlowski. A conveyor is
also provided to discharge any solids present
in the liquid stream for solid-waste disposal.
The Hydroflare technology will be espeScrew
conveyor
Waste
solids
Combustion
air
blower
cially useful for hydraulic fracturing sites
that have difficulty in removing wastewater
via trucks, or those that must use enclosed
flares to treat offgases, says Pawlowski. The
Hydroflare enclosed flare is said to achieve a
destruction efficiency for offgases of 99% or
higher. Pawlowski notes that water disposal
capacity is limited to the amount of offgas
present or by the availability of supplemental
fuel. The technology can be " dropped in "
to existing sites, provided that ground support
and proper utilities are in place. The first
Hydroflare system was recently installed at a
1,000-bbl/d production site in Texas.
New membranes resist biofouling using sunlight
M
embranes in large-scale watertreatment
processes are often
fouled by accumulation of bacteria
or their biofilms. Now, a team
of researchers from Washington University St.
Louis (WUSTL; St. Louis, Mo.; www.wustl.
edu) have combined graphene oxide and
bacterial nanocellulose to design a highly efficient
ultrafiltration membrane that resists
biofouling. " Photothermal nanomaterials like
graphene oxide absorb light effectively, and
the absorbed light is quickly converted into
heat. Thus, the membrane gets hot, killing
microorganisms on its surface and minimizing
biofilm formation. This new membrane design
uses the natural energy of sunlight to resist
biofouling on membranes, " explains YoungShin
Jun, professor of Energy, Environmental
& Chemical Engineering at WUSTL. Previously
reported nanomaterial-enabled membranes
often suffer from short operational lifetimes
and poor physical and chemical stability
that can result in nanomaterials leaching into
water, adds Srikanth Singamaneni, professor
of Mechanical Engineering and Materials Science
at WUSTL. To secure the photothermal
materials within the membrane's structure,
the team from WUSTL started with a bacterial
culture medium where cellulose nanofibers
grow into a matrix. Next, as graphene
oxide nanosheets are incorporated into the
medium, the bacteria build a nanocellulose
matrix with embedded graphene oxide. " You
end up with a composite membrane consisting
of interlocked graphene oxide and nanocellulose,
so particulate matter from the membrane
itself does not leach out into the water, "
adds Singamaneni.
According to Jun, combining the bacteria-killing
properties of photothermal materials
with the mechanical and chemical
integrity of a nanocellulose network results
in a membrane with a longer life and higher
liquid flux than commercially available membranes
operating at the same pressure. The
team believes that the new membranes will
be readily scalable, since the technology
depends on culturing bacterial nanocellulose,
a process that is already conducted
at large scales.
CHEMICAL ENGINEERING WWW.CHEMENGONLINE.COM
MARCH 2019
Ship & Shore Environmental
Mist eliminator
Water supply
from pump
Burner for
offgases and
supplemental
fuel
http://www.shipandshore.com http://www.hydrozonix http://www.braskem.co/br http://www.topsoe.com http://www.wustl http://WWW.CHEMENGONLINE.COM
Chemical Engineering March 2019

Table of Contents for the Digital Edition of Chemical Engineering March 2019
