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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