The document discusses a new low-cost water purification method developed by Professor Yu using hydrogels that can purify water using only solar power. The hydrogels contain polymers that absorb solar energy to heat up and evaporate water, distilling contaminants out of the water. This allows unsafe water from any source to be purified without infrastructure or electricity. The system is self-sustaining and can continuously treat water for over a month. The technology has potential to provide clean water at the household level in developing areas that lack water treatment.

2. A New Solution to Water
Purification in Rural Areas
A KARTHIKEYAN 07095949495

3. It’s been said that water is life, as necessary as food and oxygen to human survival.
Unsanitary water can also be a health risk, killing more than 500,000 people
worldwide every year, according to the World Health Organization. And this
problem is only going to get worse. By 2025 half of the world’s population will be
living in what are known as “water-stressed areas,” where access to clean water is
limited or nonexistent. Some 844 million people will lack basic drinking water and
another 159 million will be dependent on untreated surface water sources.

4. This is primarily a problem in the developing world, where as many as 38
percent of health care facilities are operating without modern water treatment and
roughly the same amount don’t even have clean soap and water for hand washing.
These are regions where clean water is hard to come by and related illnesses,
including cholera, dysentery, typhoid and more, are widespread. Money and
investment to solve these problems are also limited, preventing developments that
could save lives.

5. Yu, a professor of materials science and mechanical engineering at the
school, has developed a new, low-cost way to treat water safely and effectively in
the field – without the need for electricity or powered components – using a
distillation process that combines gel-polymer materials and the power of the sun.
“Right now, people mostly use multi-stage flashing or multi-effect
distillation for water desalination,” Yu says. “So basically you need to get rid of
the salt so the water can become drinkable. But these traditional industrial scale
technologies require a lot of energy and they also require very significant
infrastructure.”

6. The Texas team’s solution eliminates both of these needs by tapping solar
energy to drive its process. Arguably the cheapest, most abundant energy
source in the world, solar allows water samples to be purified anywhere, at
any time, without any specific infrastructure or tools.
Distillation is a common technique for producing clean water, and the
development by Yu’s team utilizes hydrogels – networks of polymer chains
that offer high water absorbency rates – with both hydrophilic (attracted to
water) and semiconducting (solar-adsorbing) properties, allowing for the
production of safe drinking water from almost any source, from seawater to
contaminated freshwater.

7. A MATERIALS SOLUTION
• “In this work actually used a hyper-hydrogel,” Yu says.
• “That means that this hydrogel is not one component, but rather is
actually two different polymers that are chemically blended together.
• One polymer is a water-soluble polymer called a polyvinyl alcohol, or
PVA. So PVA can actually store water, and it can contain a very significant
amount of it, typically over 95 percent. The other component is called
polypyrrole (PPy) that has a molecule structure that is conjugated so they
can actually act as a semi-conductor just like solar panels.
• Polypyrrole is one of the components that can absorb the solar energy
so you convert solar energy to locally heat up these polypyrrole, polyvinyl
and PVA networks.”
• It’s a complex process, but it works.

8. The hydrogel, which already contains a lot of water, heats up by absorbing energy
from the sun. Once the level of water in the hydrogel is evaporated off and
distilled, it starts to pull in untreated water that begins to evaporate.
By evaporating the water off and capturing it you’re able to get rid of whatever
salt or other contaminates are in the water, making it safe for drinking.
It’s a self-sustaining system that replenishes itself over and over again and keeps
treating water until the solar energy used to power the evaporation runs out.

9. Desalination was used to demonstrate the technology’s potential because salt is
notoriously difficult to remove from water. The hydrogel-based system can also filter
out a number of different contaminants or pollutants from unsafe water.
It’s also worth noting that the hydrogel material can be used over and over again; it
doesn’t get clogged up with salt or contaminants and replaced between uses.
As long as the hydrogels are kept wet so that salt can’t crystallize they can work
continuously for long periods of time. In testing, Yu’s team demonstrated that the
system could operate unimpeded for more than a month without any decay in overall
performance.

10. SCALING PURIFICATION
Yu says the hydrogel materials that are used in the process are focused on
household use, with 8- to 12-inch wafers that can be used to treat a few gallons of
water at a time. At that scale, he says, the technology can likely have the most
immediate impact.
“Even given this current system with the current materials, it's not like we
are talking about spending $1,000 to build this instrument,” Yu says. “You can have
a simple design with a container and these solar-sopping hydrogel materials and
then just start collecting water. Because it can be continuous use, we don't need to
have a cleaning system, so you can just put it into the sink and if you have a
continuous water supply you don't even need to do anything to enable this water
washing.”

11. Yu, who has two patents related to this hydrogel technology, says the
next step for his team is to find even cheaper, better performing materials than
the PVA and PPy that the system currently uses and to find ways to truly scale
the system.
They’re working with water researchers and civil engineers at the
university to develop more systematic evaporation systems that are capable of
solar-treating far larger water samples than is currently possible, focusing on
bacteria and foreign organic materials contamination.