Revolutionizing the Water Purification Industry – the Roles of Sunlight and ‘Hydrogels’

by Dr. Jonathan Doyle - Updated November 02, 2021
Recent collaborative research between the researchers at the University of Texas, Austin, and Lockheed Martin Corporation has led to the invention of a hydrogel-based water purification technique.Many features make this technique outstanding, including a 12x higher efficiency compared to present technologies.

Drinkable Water – Challenges and Progress

The world needs an affordable purification technique that makes filthy water drinkable. Unfortunately, millions of people worldwide resort to unsafe water every day because of their inabilities to access or afford personal purification systems. Another contributory factor to this is the non-inclusion of the most water-starved locations in the extensive purification efforts.
Common purification techniques include pasteurizing and boiling water, but these take a lot of time and labor to achieve. Moreover, some regions cannot simply get all they need for these procedures.
We have also seen water purification using a solar-based water distillation device. The device is essentially a bottle with a black bottom exposed to sunlight. Once the water evaporates, it forms on the top of the bottle and gradually settles into a container.
Although this is an effective technique, it is inefficient because evaporation cannot occur without heating the bottle and its contents. Fortunately, we now have something better and more efficient, thanks to recent research.

Newer Water Purification Techniques

Guihua Yu, an associate professor of materials science and mechanical engineering at the University of Texas Cockrell School of Engineering, recently led a research team to develop a more affordable and small-footprint technique using gel-polymer hybrid materials.
These ‘hydrogels’ are semiconducting (solar-absorbing) and hydrophilic (attracted to water), making them suitable for extracting safe, clean, and healthy drinking water from any source.
This technique works for even oceans or tainted supplies. Demonstrating the technique, the sponge was put over the unclean water in a solar still, which led to the rapid evaporation of the water. The evaporation is caused by weaker hydrogen bonds formed by the contact between a layer of water and the sponge.
Primarily, the tablet is designed to produce hydrogen peroxide, which combines with carbon particles to halt the metabolism processes of bacteria, thereby killing them. According to the research team, the purification process is safe without the production of any harmful byproducts.
This technique has remarkable potentials to improve the water scarcity problems rocking the entire world. This is because it can purify filthy water in a shorter time. For example, it takes an hour or less to purify a liter of river water using the hydrogel tablet. This, coupled with its ease of use and high effectiveness, makes it an ideal choice.
Under direct sunlight, the hydrogel can produce water vapor that is subsequently collected in a condenser for freshwater supply. It also has desalinating qualities, which have been tested and proven on water from the salt-rich Dead Sea. Finally, the technique meets the drinking water standards as set by the US Environmental Protection Agency and the World Health Organization.

Hydrogel vs. Traditional Filtration Technology

Physical water filtration techniques like ultrafiltration and reverse osmosis work differently than the hydrogel purification technique. Let’s take a look at each of these techniques.

How does Reverse Osmosis work?

The simple design of the reverse osmosis water filtration technique is one of its top qualities. A semi-permeable membrane allows the forced passage of water to separate the water molecules from the pollutants. Our latest blog has introduced reverse osmosis in a very detailed way: What Is a Reverse Osmosis System and How Does It Work. It is essentially the removal of dissolved inorganic solids from a solution. The filter media traps the impurities in traditional filtration, but this case is different. The filtration occurs via a series of filters, and only the filtered water ends up in the storage tank while the pollutants are flushed out of the system.

How does ultrafiltration work?

As a membrane filtration technique, ultrafiltration relies on a membrane that doubles as a barrier, keeping harmful bacteria, viruses, and other contaminants out of clean water. Therefore, the technique uses a refined membrane to force water through it while blocking other particles larger than the water molecules. Therefore, only pure water and dissolved minerals are found on the other side of the membrane. What Is Ultrafiltration Membrane And How Does It Work? describes ultrafiltration vividly for your reference.

Similarities and Differences

The three filtration techniques – hydrogels, ultra-filtration, and reverse osmosis – all remove up to 99.9% harmful pollutants from water. These pollutants include heavy metals, harmful chemicals, viruses, and bacteria.
But the filtration principles are not the same. For example, hydrogels rely on solar, evaporation, and pure water collection, with the contaminants left in the original solutions. In addition, the hydrogel tablets produce hydrogen peroxide, which is harmful to germs, killing their cell components and halting their metabolism.
In the cases of ultrafiltration and reverse osmosis, the two techniques rely on a specialized membrane to intercept impurities. Then, rather than kill or inactivate the germs, they flush them out alongside the wastewater.
The power source is also different in either case. While hydrogel works fine with limited solar power, reverse osmosis needs electricity to operate. Therefore, the former is green and eco-friendly. Ultrafiltration requires no electricity.
The only downside of the hydrogel technique is the speed. Considering it takes about an hour to purify a liter of river water, it is best to purify water in advance. It is not the ideal filtration technique if you always need pure water instantly.

Finally…

We can conclude that hydrogel is a remarkable water purification with a lot of potentials. It is safer, eco-friendly, and effective. There are plans in work to commercialize it once it is proved. The research team expects and is ready for industry inquiries for scalability testing.
Natural supplies cannot meet the global demand for fresh and healthy drinking water. Therefore, it is important to explore a technology that proffers an effective yet simpler solution.

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