The Thickness of the New Reverse Osmosis Membranes can be altered

The Thickness of the New Reverse Osmosis Membranes can be altered

A new innovation in reverse osmosis membranes helps in obtaining a much cleaner water from the seawater.

Water plays a crucial role in human survival as it accounts for nearly 70% of our body. The human body and its internal anatomy require water in order to function. Cells, organs, and tissues help our body to regulate its temperature. Clean water is something that is directly proportional to our health. Clean water is a blessing that several countries are robbed of. Thus, water purification takes place. Many of the philanthropists, celebrities, and humanitarians have worked for the cause of delivering clean water to those who cannot access it. Audrey Hepburn spoke about the importance of clean water and said,

“Water is life, and clean water means health”.

Numerous processes can attain water purification; one of the methods is by using the Reverse Osmosis technology. Reverse Osmosis is a technology that use a semipermeable membrane to remove ions, molecules, and particles from water. This process uses force to function. Seawater is pushed through a membrane that is capable of removing salts and other small molecule contaminants. This process has an excellent success rate, but it is not applied in all scenarios for a number of reasons. The amount of energy consumed by this procedure is very high. Additionally, there is a tendency for membranes to foul. The conventional technique of Reverse Osmosis was not immune to change and variability which urged the researchers at the University of Connecticut to upgrade the process of membrane creation.

It involves an additive methodology by using electrospraying technology. This approach allowed the scientists to create and experiment with ultra-thin and ultra-smooth polyamide membranes. As a result, the frequency of fouling of membranes diminished alongside a substantial decrease in energy consumption. The orthodox technique of reverse osmosis leaves less room for experimentation. It also offers flexibility to the process as the fundamental properties of the membranes can be altered. Jeffery McCutcheon, an Associate Professor for Chemical and Biomolecular Engineering, praised this latest technology by saying,

“Today’s membranes for reverse osmosis are not made in a way that allows their properties to be controlled. Our approach uses an ‘additive’ technique that allows for control of the membrane’s fundamental properties such as thickness roughness, which is currently impossible using conventional methods.”

In general, the membrane consists of three layers. The bottom layer is made up of unwoven Polyester cloth, having a thickness of 100-200 µm, which supports the entire membrane’s structure. The middle layer is comprised of Polysulfone (PSF) or Polyethersulfone (PES) with the thickness of 30 to 50 µm. Finally, the top layer, which is made up of Polyamide (PA) or Polyetherimide (PEI) who are supported by either Polysulfone or Polyethersulfone, has an average density of 100 to 200 nm. This aids in removing solutes from impure water.

The standard method for developing Reverse Osmosis Membranes have not altered for around 40 years now. That conventional method is known as ‘Interfacial Polymerization’. This technique depends upon the self-dissolution reaction between an aqueous phase amine and an organic phase acid chloride monomer. The polyimides films formed are thin and permeable to water. This purification method was no doubt exceptional but it did not allow membranes to have changeable thicknesses and controllable roughness to improve water flow thus initiating pollution.

The additive methodology developed by researchers at the University of Connecticut allows the thickness and roughness to vary. Previously, the recorded membrane had a fixed thickness of 100 to 200 nanometers. The electrospraying technology allows the researchers to develop a film as thin as 15 nm. In addition to that, this technology also allows 4 nm increments in the thickness of these membranes. Moreover, this method allows the variation for the membrane’s roughness. The afresh roughness formed is as low as 2 nm whereas, formerly the roughness recorded was as high as 80 nm.

This technology allowed high salt elimination rate and assured good sustainability under high pressure. The facts that this technique consumes less energy (essential for mass production) and is nature-friendly increases its utility many times. Therefore, it can be concluded that it is a mass-produced technology which is making its way around the world to ensure that none of us run out of clean water. McCutcheon summed it up in the following words:

“These benefits would be magnified in large-scale membrane manufacturing and make the process more “green” than it has been for the past 40 years”.

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