A person can live about three weeks without food, but only about three days without water. “You can go 100 hours without drinking at an average temperature outdoors,” says Claude Piantadosi of Duke University. “If it’s cooler, you can go a little longer. If you are exposed to direct sunlight, it’s less.”
Today, more than two billion people all around the world lack access to clean and safe drinking water. The search for water is a primary factor in global migration patterns. All those people moving around leads to conflicts within the global community — conflicts that can lead to war. As we all learned from reading The Rime Of The Ancient Mariner in school, sea water cannot sustain human life. “Water, water everywhere and not a drop to drink,” moaned the intrepid sailor.
Researchers in Australia and the US have discovered a new class of materials called metal-organic frameworks, which have the largest internal surface area of any known substance. Similar to sponges, they can capture, store, and release chemical compounds. One potential use is removing the dissolved minerals in sea water to make it drinkable.
The team that made this discovery consisted of professors Huacheng Zhang, Huanting Wang, and Zhe Liu at Monash University in Melbourne, professor Benny Freeman at The University of Texas in Austin, and Dr Anita Hill of the Commonwealth Scientific and Industrial Research Organization, Australia’s leading scientific research agency.
With further development, the MOF membranes they created have the potential to perform the dual functions of removing salts from seawater and separating metal ions in a highly efficient and cost effective manner, offering a revolutionary new technological approach for the water and mining industries. One possible application could be removing lithium from the highly contaminated wastewater that results from fracking operations.
“The prospect of using MOFs for sustainable water filtration is incredibly exciting from a public good perspective, while delivering a better way of extracting lithium ions to meet global demand could create new industries for Australia,” Dr Hill said. Today, creating drinking water from sea water is either a highly energy intensive process that involves distillation, or a slow process that involves forcing the source water through a membrane in a process known as reverse osmosis.
Professor Huanting Wang says, “We can use our findings to address the challenges of water desalination. Instead of relying on the current costly and energy intensive processes, this research opens up the potential for removing salt ions from water in a far more energy efficient and environmentally sustainable way.”
“Also, this is just the start of the potential for this phenomenon. We will continue researching how the lithium ion selectivity of these membranes can be further applied. Lithium ions are abundant in seawater, so this has implications for the mining industry who current use inefficient chemical treatments to extract lithium from rocks and brines. Global demand for lithium required for electronics and batteries is very high. These membranes offer the potential for a very effective way to extract lithium ions from seawater, a plentiful and easily accessible resource.”
Mining minerals from sea water could be hugely important from an economic standpoint, but providing abundant supplies of drinking water at low cost to communities around the world that suffer from water shortages is arguably even more important from a humanitarian perspective.