Ahmed El-Shafei, et al. : Pervaporative Desalination -- Articles & patents

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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.

h desalination.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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