New Device Can Desalinate Seawater

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Let’s face it: Access to clean water is something we take for granted. At this very moment, chances are you’re no more than a 30-second walk from a faucet. It’s not all that easy for everybody, though. Scientists estimate that about 4 billion people — 66 percent of the world’s population — don’t have access to fresh water for at least one month out of a year. With an increasing amount of water shortages at home and abroad, it’s time we explored new methods of making what’s available safer to drink. One of the methods is to desalinate seawater.

Desalination Demystified

Desalination, the process of removing salt from saltwater, sounds simple. However, it’s much more complicated in practice. Making saltwater drinkable requires a huge amount of energy — typically from fossil fuels — and often leaves behind environmentally damaging waste.

The plants themselves must also comply with various environmental protection standards. Though they’re in place for good reason, the increased costs could drive up already high water prices in stricken areas.

Thanks to recent advances in desalination techniques, this could all be set to change.

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Graphene Membranes

A research team at the University of Manchester recently reported that they’ve discovered a far more useful method of desalination using complex graphene-oxide membranes. This project builds upon previous research employing the membranes to filter out nanoparticles and organic molecules. At that time, the filters did not have any way of removing the common salts encountered in seawater.

The problem was, when exposed to water, the membrane would swell, allowing small salts to bypass the filter. Through research and testing, the team developed a way to prevent the swelling and control the pore size, allowing for better filtration.

Science at Work to Desalinate Seawater

The membranes work by blocking salt on a microscopic level. When salt dissolves in water, water molecules form a sort of shell around the salt molecules. The pores of the membrane are so small that they allow the water molecules through without the larger salt molecules. This process blocks 97 percent of the salt from flowing through.

According to joint-authors Jijo Abraham and Dr. Vasu Siddeswara Kalangi, the ability to control the pore size of the membrane opens up the technology to many other applications than just desalination. Scientists could, for example, filter ions by size.

Hope for the Future

The beauty of the graphene-oxide filter is that it’s comparatively simple to make in a lab, especially compared with a graphene lattice, which is hard to produce in significant quantities and must have the holes drilled into it.

To mitigate the swelling, the team used the deviously simple solution of sandwiching the filter between two walls made of common epoxy. This restriction is what allows people to fine-tune what passes through the filter.

Thanks to the cost-effectiveness of this filter, areas with few economic resources could start producing fresh water at a fraction of the cost of a desalination plant. As the UN estimates water scarcity will only increase in urban areas and developing countries, the sooner this technology is perfected, the better.

Though it still needs refining in terms of durability and ease of cleaning, the development team is hopeful their research will play a part in mitigating our impending water crisis.