Nav: Home

Green water-purification system works without heavy metals or corrosive chemicals

February 07, 2019

Scientists at the Institute of Process Engineering (IPE) at the Chinese Academy of Sciences in Beijing and Yangzhou University (YZU) in Jiangsu have developed an effective and energy-efficient technique for purifying water by using graphitic carbon nitride sheets.

Their prototype, presented February 7 in the journal Chem, purified pathogen-rich water in 30 min, killing over 99.9999% of bacteria, such as E. coli, meeting China's requirements for clean drinking water. Unlike metal-based photocatalytic disinfectants, it achieved this standard without leaving behind secondary pollution or heavy-metal-ion residues, offering a promising alternative to less eco-friendly technologies.

"The future application of photocatalytic disinfection technology can significantly relieve clean-water scarcity and global energy shortage," says Dan Wang, a professor at the Institute of Process Engineering and a senior author on the paper.

Unlike traditional water-purification processes using ultraviolet light, chlorination, or ozone disinfection, photocatalytic methods offer environmentally safe water treatment--as long as they use the right catalyst. But unfortunately, these greener catalysts tend to be less efficient than metal-based varieties. Widely studied carbon-based catalysts, such as carbon nanotubes and graphene oxide, aren't quite effective enough for practical water-treatment purposes because they fail to produce enough reactive oxygen to overcome pathogens.

The team from IPE and YZU manages to bypass these failings with a unique catalytic design. They utilize nanosheets of graphitic carbon nitride, an ultra-thin two-dimensional material with the right electronic properties to absorb the light and generate reactive oxygen. This configuration helped to facilitate the reaction by generating plenty of hydrogen peroxide, which efficiently kills bacteria by oxidizing their cell walls and wreaking havoc on their chemical structures.

Ultimately, Wang believes that these results, as well as the simplicity of the design and inexpensive materials, mean the technology should be relatively easy to develop on a larger scale. "The scale-up for both the catalysts and the device is not difficult," he says. "The construction of this material is completely metal-free, and one of the key components, the plastic bag, is commercialized, which makes it easy to obtain."

The team intends to hone the technique before it is ready for commercial use. As the next steps, they plan to improve efficiency by expanding the edge of the material's ability to absorb photons, develop antibacterial fibers, and refine the nanosheet preparation process.

However, he acknowledges that this bacteria-killing system is not intended to single-handedly purify water. "Purification needs other devices for removing heavy-metal ions, adjusting pH, and removing residue," he says. "We need to combine our system with others to meet water-purification requirements."
-end-
The researchers received financial support from the National Natural Science Foundation of China, the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Jiangsu Province Research Program on analytical methods and techniques on the shared platform of large-scale instruments and equipment.

Chem, Teng and Yang et al.: "Edge-Functionalized g-C3N4 Nanosheets as a Highly Efficient Metal-free Photocatalyst for Safe Drinking Water" https://www.cell.com/chem/fulltext/S2451-9294(18)30572-2

Chem (@Chem_CP) is the first physical science journal published by Cell Press. A sister journal to Cell, Chem, which is published monthly, provides a home for seminal and insightful research and showcases how fundamental studies in chemistry and its sub-disciplines may help in finding potential solutions to the global challenges of tomorrow. Visit: http://www.cell.com/chem. To receive Cell Press media alerts, contact press@cell.com.

Cell Press

Related Bacteria Articles:

Conducting shell for bacteria
Under anaerobic conditions, certain bacteria can produce electricity. This behavior can be exploited in microbial fuel cells, with a special focus on wastewater treatment schemes.
Controlling bacteria's necessary evil
Until now, scientists have only had a murky understanding of how these relationships arise.
Bacteria take a deadly risk to survive
Bacteria need mutations -- changes in their DNA code -- to survive under difficult circumstances.
How bacteria hunt other bacteria
A bacterial species that hunts other bacteria has attracted interest as a potential antibiotic, but exactly how this predator tracks down its prey has not been clear.
Chlamydia: How bacteria take over control
To survive in human cells, chlamydiae have a lot of tricks in store.
Stress may protect -- at least in bacteria
Antibiotics harm bacteria and stress them. Trimethoprim, an antibiotic, inhibits the growth of the bacterium Escherichia coli and induces a stress response.
'Pulling' bacteria out of blood
Magnets instead of antibiotics could provide a possible new treatment method for blood infection.
New findings detail how beneficial bacteria in the nose suppress pathogenic bacteria
Staphylococcus aureus is a common colonizer of the human body.
Understanding your bacteria
New insight into bacterial cell division could lead to advancements in the fight against harmful bacteria.
Bacteria are individualists
Cells respond differently to lack of nutrients.

Related Bacteria Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Digital Manipulation
Technology has reshaped our lives in amazing ways. But at what cost? This hour, TED speakers reveal how what we see, read, believe — even how we vote — can be manipulated by the technology we use. Guests include journalist Carole Cadwalladr, consumer advocate Finn Myrstad, writer and marketing professor Scott Galloway, behavioral designer Nir Eyal, and computer graphics researcher Doug Roble.
Now Playing: Science for the People

#529 Do You Really Want to Find Out Who's Your Daddy?
At least some of you by now have probably spit into a tube and mailed it off to find out who your closest relatives are, where you might be from, and what terrible diseases might await you. But what exactly did you find out? And what did you give away? In this live panel at Awesome Con we bring in science writer Tina Saey to talk about all her DNA testing, and bioethicist Debra Mathews, to determine whether Tina should have done it at all. Related links: What FamilyTreeDNA sharing genetic data with police means for you Crime solvers embraced...