Researchers from Princeton University have invented a new method of filtering water. It involves using Carbon dioxide in a low-cost water treatment system to remove dirty particles and reduce the need for complex and expensive filters.
It basically works by injecting CO2 gas into a stream of water. The gas will temporarily change the water’s chemistry, causing the contaminating particles to react to it and move to one side of the filtering channel due to its electrical charge, allowing the clean and filtered water to pass through the other channel.
Source: New Atlas
“You could potentially use this to clean water from a pond or river that has bacteria and dirt particles,” said Sangwoo Shin, assistant professor of mechanical engineering at the University of Hawaii at Manoa. Their paper published in the journal Nature Communications describes how their laboratory scale CO2 filter is more efficient at removing impurities in water than traditional microfiltration systems, as well as the system requiring only 1 moving part and no physical filter that needs maintenance or replacement.
When CO2 is mixed with water, the solution becomes more acidic, and it creates charged particles, or ions. One of the ions created is a positively charged hydrogen atom which moves very quickly in the solution, and the other one is a negatively charged bicarbonate molecule which moves more slowly. Their movement creates a subtle electric field that attracts the contaminating particles (which also have charged ions) and then flushes them out toward one side of the water stream, leaving clean water on the other.
Source: Nature Communications
Not only is this method more effective than conventional systems, it’s also cheaper since it has very few moving parts, and there are no actual filters and membranes that can clog the system and need to be cleaned or replaced on a regular basis.
The researchers hope to scale up the system next so that it could be used in actual water treatment plants for larger communities. “In Hawaii, we have a fresh water problem,” said Shin. “We hope to scale up the device to help solve it.”