At this moment, you may not feel that it is difficult to drink pure water when you stumble on the bed or struggle to squeeze into the subway. But in fact, about one billion people on this planet can't get safe drinking water.

According to the World Bank, 88% of today's diseases are caused by poorly drinking water.

Water pollution is a very serious social problem

Therefore, water purification and filtration are particularly important. But what is even more sad is that most of the polluted water sources are concentrated in developing countries, and the average living standard is not high, but the price of filters is very expensive.

Recently, researchers at Princeton University, Unilever, and the University of Hawaii have developed a technology for low-cost water purification systems that may save hundreds of millions of lives in the future.

This system uses carbon dioxide (CO2) as a filter particle for purification.

It injects carbon dioxide gas into the contaminated water stream, and the mixing of water and gas temporarily changes the chemical properties of the water. Chemical changes can cause contaminating particles to concentrate on one side depending on the charge movement. Through this migration, the researchers were able to break down the water stream and filter out the suspended contaminating particles.

Sangwoo Shin, Assistant Professor of Mechanical Engineering at the University of Hawaii at Manoa, said:

“You can use this method to clean ponds or rivers that contain bacteria and dirt particles.”

The researchers published this technical paper in the journal Nature Communication, which describes how to create a laboratory-scale filter that removes three orders of magnitude (1000 times) more efficiently than traditional microfiltration systems.

he system consumes less energy and the bottled carbon dioxide is the only moving part (except for the pump that is responsible for the flow) and there are no physical filters or membranes that are clogged or need to be replaced.

Carbon dioxide changes the chemical properties of water by its acidity: acidity means that when CO2 is dissolved in water, charged particles called ions are produced. The positively charged hydrogen atoms in these ions can move through the aqueous solution very quickly.

Another negatively charged bicarbonate molecule moves more slowly. The movement of ions through the water creates a subtle electric field that attracts particles in the water on one side of the water stream, so that particles with the same electrode are concentrated on the same side.

Because most contaminants have a certain amount of surface charge, the electric field is an effective way to push it out of the water.

The researchers' equipment uses different electrodes of different particles and a subtle power plant to draw contaminants into the side of the flow and then break the water into two channels:

One path carries water containing contaminating particles and the other path keeps water. Since the system does not use a filter membrane or a mechanical filter, there is no problem of clogging. Researcher Howard Stone said:

The use of soluble gases as a means of controlling particles in solution may be used in other industries and may not be limited to the field of water filtration: "The principles we hope to explore in this study will also have an impact in other areas of research."

Carbon dioxide is particularly useful as a filter gas in developing countries because it does not require the need to replace expensive filters at regular intervals, and the cost is much lower. Not only that, but its operation is also simple and convenient, only need to bottled carbon dioxide.

LifeStraw straw

Liquidity, the US startup, also hopes to use a nanotechnology-supported cup to filter contaminated water in real time;

Researchers at the University of St. Louis in Washington found that graphene-based bio-foam boards can be used to filter contaminated water...

In short, we hope that these technologies will allow everyone on the planet to drink healthy, pure water.