rexresearch.com
Ahmed El-Shafei,
et al.
Pervaporative Desalination
http://www.scidev.net/global/water/news/egyptian-filters-seawater-environment.html
Egyptian method filters seawater in
minutes
Researchers at Alexandria University in Egypt have unveiled a
cost-effective desalination technology which can filter highly
salty water in minutes.
The technology is based on membranes containing cellulose acetate
powder, produced in Egypt. The powder, in combination with other
components, binds the salt particles as they pass through, making
the technique useful for desalinating seawater.
“The membrane we fabricated can easily be made in any laboratory
using cheap ingredients, which makes it an excellent option for
developing countries,” says Ahmed El-Shafei, an associate
professor of agricultural and biosystems engineering in Alexandria
University, and an author of the study.
“Using pervaporation eliminates the need for electricity that is
used in classic desalination processes, thus cutting costs
significantly.” -- Ahmed El-Shafei, Alexandria University
The technology uses pervaporation, a technique by which the water
is first filtered through the membrane to remove larger particles
and then heated until it vaporises. The vapour is then condensed
to get rid of small impurities, and clean water is collected.
According to the research paper, published in Water Science and
Technology last month, this method can be used to desalinate water
which contains different types of contamination, such as salt,
sewage and dirt. This kind of water is difficult to clean quickly
using existing procedures.
The membrane technology in combination with vaporisation can be
applied in remote settings, as it requires only the membranes for
the filtering process, and fire to vaporise the filtered water,
the researchers say.
“Using pervaporation eliminates the need for electricity that is
used in classic desalination processes, thus cutting costs
significantly,” says El-Shafei.
Pervaporation is used to separate organic liquids, like alcohols,
and is one of the more common systems used in sewage treatment to
separate water from organic solvents. The technology has been
around since the mid-90s, Helmy El-Zanfaly, a professor of water
contamination at Egypt’s National Research Center.
But, he says, “What is new is making the membrane locally, using
materials abundant in Egypt and developing countries.” El-Zanfaly
adds that existing pervaporation membranes are fabricated using
complicated procedures, making them unsuitable for cheap
production.
http://phys.org/news/2015-09-egyptian-method-filters-seawater-minutes.html
September 10, 2015
Egyptian method filters
seawater in minutes
by Rasha Dewedar
Researchers at Alexandria University in Egypt have unveiled a
cost-effective desalination technology which can filter highly
salty water in minutes.
The technology is based on membranes containing cellulose acetate
powder, produced in Egypt. The powder, in combination with other
components, binds the salt particles as they pass through, making
the technique useful for desalinating seawater.
"The membrane we fabricated can easily be made in any laboratory
using cheap ingredients, which makes it an excellent option for
developing countries," says Ahmed El-Shafei, an associate
professor of agricultural and biosystems engineering in Alexandria
University, and an author of the study.
The technology uses pervaporation, a technique by which the water
is first filtered through the membrane to remove larger particles
and then heated until it vaporises. The vapour is then condensed
to get rid of small impurities, and clean water is collected.
According to the research paper, published in Water Science and
Technology last month, this method can be used to desalinate water
which contains different types of contamination, such as salt,
sewage and dirt. This kind of water is difficult to clean quickly
using existing procedures.
The membrane technology in combination with vaporisation can be
applied in remote settings, as it requires only the membranes for
the filtering process, and fire to vaporise the filtered water,
the researchers say.
"Using pervaporation eliminates the need for electricity that is
used in classic desalination processes, thus cutting costs
significantly," says El-Shafei.
Pervaporation is used to separate organic liquids, like alcohols,
and is one of the more common systems used in sewage treatment to
separate water from organic solvents. The technology has been
around since the mid-90s, Helmy El-Zanfaly, a professor of water
contamination at Egypt's National Research Center.
But, he says, "What is new is making the membrane locally, using
materials abundant in Egypt and developing countries." El-Zanfaly
adds that existing pervaporation membranes are fabricated using
complicated procedures, making them unsuitable for cheap
production.
"The technology implemented in the study is much better than
reverse osmosis, the technology currently used in Egypt and most
of the countries in the Middle East and North Africa," El-Zanfaly
says. "It can effectively desalinate water with high concentration
of salt like that of the Red Sea, where desalination costs more
and yields less."
The technology can be adapted for commercial use by fabricating
larger sheets of the membrane and cutting these into suitable
swathes, according to El-Shafei. The next step for the team is to
establish a small desalination unit as a pilot project for the
technology.
http://www.researchgate.net/publication/277972638_Desalination_of_simulated_seawater_by_purge-air_pervaporation_using_an_innovated_fabricated_membrane
Water Science & Technology (Impact Factor: 1.11).
08/2015
http://wst.iwaponline.com/content/72/5/785
20 September 2015
DOI: 10.2166/wst.2015.277
Desalination of simulated seawater by
purge-air pervaporation using an innovative fabricated
membrane
Mona Naim, Mahmoud Elewa, Ahmed El-Shafei, Abeer Moneer
Abstract
An innovative polymeric membrane has been invented, which presents
a breakthrough in the field of desalination membranes. It can
desalinate simulated seawater of exceptionally high concentration
to produce a high flux of potable water with over 99.7% salt
rejection (%SR) in a once-through purge-air pervaporation (PV)
process. A set-up was constructed for conducting the desalination
experiments and the effect of initial salt solution concentration
(Ci) and pervaporation temperature (Tpv) on the water flux (J),
%SR, separation factor, and pervaporation separation index were
determined. The membrane was prepared by the phase-inversion
technique, of a specially formulated casting solution consisting
of five ingredients, after which the membrane was subjected to a
post-treatment by which certain properties were conferred. The
results confirmed that the salinity of the pervaporate was
independent of Ci (all %SR above 99.7). The best result was at Tpv
= 70 °C, where J varied from 5.97 to 3.45 l/m2 h for Ci = 40–140 g
NaCl/l, respectively. The membrane morphology was confirmed to be
asymmetric. The contact angle was immeasurable, indicating the
membrane to be super-hydrophilic. Activation energies computed
using Arrhenius law were, under all conditions investigated, less
than 20 kJ/mol K.
hdesalination.biz/news/news_story.asp?id=8182
Egypt researchers unveil new low-cost
membrane for desalting
Researchers at Alexandria University in Egypt have published what
they claim to be a new low-cost-desalination technology that uses
little energy and cheap membrane materials.
The technology uses pervaporation - vaporisation of permeate drawn
through a membrane. The researchers developed a cellulose acetate
membrane combined with other components, to filter particles and
bind salts before the permeate is vaporised using a heat source.
The researchers, led by associate professor of agricultural and
biosystems engineering Ahmed El-Shafei, said the system
desalinated simulated seawater of "exceptionally high
concentration" to produce a high flux of potable water with over
99.7% salt rejection. It used once-through, purge-air
pervaporation.
In their report in Water Science and Technology, El-Shafei's team
said the best result was at 70 °C, where flux varied from 5.97
l/m² at a salt concentration of 40 g NaCl/l, to 3.45 l/m²h for 40g
NaCl/l.
"The membrane we fabricated can easily be made in any laboratory
using cheap ingredients, which makes it an excellent option for
developing countries," said El-Shafei.
In their paper, Desalination of simulated seawater by purge-air
pervaporation using an innovative fabricated membrane, the
researcher explained that the membrane was prepared by the common
phase-inversion technique, using a casting solution with multiple
components. Once cast, the membrane was subjected to further
treatments to produce its hydrophilic and other properties.
The researchers said the membrane had an asymmetric pore size
distribution and the contact angle was "immeasurable" which
demonstrated the membrane was exceptionally hydrophilic.
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