Chemical Engineering March 2017 - 11

A new adsorbent for
wastewater treatment
A
team at the Graduate School of Energy, Environment,
Water and Sustainability (EEWS) of Korea
Advanced Institute of Science and Technology
(KAIST, Daejeon; www.kaist.ac.kr), led by professor
Cafer T. Yavuz has developed a water-treatment
adsorbent that can selectively remove water-soluble
micromolecules, such as those of dyes and pesticides,
which cannot be removed completely during conventional
water-treatment processes. The adsorbent has
the added advantages of being inexpensive, easily synthesized
and renewable.
In order to remove very small molecules - which
also tend to be electrically charged - with high solubility
in water, and to do so selectively, the team had
to develop a new adsorbent technology. It developed
a fluorine-based nanoporous polymer that has all the
desirable properties. By controlling the size of the pores,
this adsorbent can selectively adsorb aqueous micromolecules
of less than 1-2 nm in size.
To separate specific contaminants, the adsorbent
had to be able to interact strongly with the target substance.
Fluorine, the most electronegative atom, interacts
strongly with charged soluble organic molecules.
The incorporation of fluorine enabled the adsorbent to
separate charged organic molecules up to eight times
faster than neutral molecules.
The adsorbent could see wide industrial application,
such as in batch-adsorption tests, and in column separation
for size- and charge-specific adsorption. Yavuz says the
charge-selective properties of fluorine could be used in desalination
or water-treatment processes using membranes.
Chemicals from bagasse
T
oray Industries, Inc. (www.toray.us) and Mitsui
Sugar Co. (both Tokyo, Japan; www.mitsuisugar.co.jp)
have started a six-year project to
demonstrate the production of useful materials
from bagasse, with support from the New Energy and
Industrial Technology Development Org. (NEDO; Kawasaki
City, Japan; www.nedo.go.jp). Cellulose Biomass
Technology Co. (CBT) - a joint venture (JV) established
by Toray (67%) and Mitsui Sugar (33%) - plans
to demonstrate the production of cellulosic sugar from
the waste bagasse that is generated at the sugar factory.
The cellulosic sugar will then be used as feedstock
for making other useful chemicals.
A demonstration plant is being constructed that will
include pulverization, pretreatment, enzyme-saccharization
and membrane-separation processes, and will process
15 ton/d of dried bagasse, which corresponds to
the production of 1,400 ton/yr of cellulose sugar.
Among the new technologies to be demonstrated
are: energy-saving,
membrane-based
separation
technology, developed by Toray; and extraction technology,
developed by Mitsui Sugar. The high-quality
cellulose sugar product can be used as a feedstock
for making useful bio-chemicals and chemicals, such
as ethanol, lactic acid, succinic acid, poly-phenol and
phenol compounds.
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11
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Chemical Engineering March 2017

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