Print Page | Contact Us | Report Abuse | Sign In | Register
Graphene Updates
Blog Home All Blogs

How to purify water with graphene

Posted By Graphene Council, The Graphene Council, Wednesday, May 15, 2019
Updated: Wednesday, May 1, 2019
Scientists from the National University of Science and Technology "MISIS" together with their colleagues from Derzhavin Tambov State University and Saratov Chernyshevsky State University have figured out that graphene is capable of purifying water, making it drinkable, without further chlorination. "Capturing" bacterial cells, it forms flakes that can be easily extracted from the water. Graphene separated by ultrasound can be reused. The article on the research is published in Materials Science & Engineering C.

Graphene and graphene oxide (a more stable version of the material in colloidal solutions) are carbon nanostructures that are extremely promising for Biomedicine. For example, it can be used for targeted drug delivery on graphene "scales" and for tumor imaging. Another interesting property of graphene and graphene oxide is the ability to destroy bacterial cells, even without the additional use of antibiotic drugs.

Scientists from the National University of Science and Technology "MISIS" together with their colleagues from Derzhavin Tambov State University and Saratov Chernyshevsky State University have conducted an experiment, injecting graphene oxide into solutions (nutrient medium and the saline) containing E.coli. Under the terms of the experiment, saline "simulated" water, and the nutrient medium simulated human body medium. The results showed that the graphene oxide along with the living and the destroyed bacteria form flakes inside the solutions. The resulting mass can be easily extracted, making water almost completely free of bacteria. If the extracted mass is then treated with ultrasound, graphene can be separated and reused.

"As working solutions, we chose a nutrient medium for the cultivation of bacteria (it is to the natural habitat of bacteria), as well as ordinary saline, which is used for injections. As a tested bacterial culture, E. coli modified with a luminescent agent was used to facilitate visualization of the experiments, was used", Aleksandr Gusev, one of the authors, Associate Professor of NUST MISIS Department of Functional Nanosystems and High-Temperature Materials, comments.

Graphene oxide was added to the nutrient solution in different concentrations - 0.0025 g/l, 0, 025 g/l, 0.25 g/l and 2.5 g/l. As it turned out, even at a minimum concentration of graphene oxide in saline (water), the observed antibacterial effect was significantly higher than in the nutrient medium (human body). Scientists believe that this indicates not a mechanical, but a biochemical nature of the mechanism of action, that is, since there are far fewer nutrients in the saline solution, the bacteria moved more actively and was "captured" by the scales of graphene oxide more often.

According to the fluorescent test data, confirmed by laser confocal microscopy and scanning electron microscopy, at 2.5 g/l concentration of graphene oxide, the number of bacteria decreased several times compared to the control group and became close to zero.

While it is not yet known exactly how the further destruction of bacteria occurs, researchers believe that graphene oxide provokes the formation of free radicals that are harmful to bacteria.

According to scientists, if such a purification system is used for water, it will be possible to avoid additional chlorination. There are other advantages: decontamination with graphene oxide has a low cost, in addition, this technology is easy to scale to the format of large urban wastewater treatment plants.

Tags:  Aleksandr Gusev  Derzhavin Tambov State University  Graphene  National University of Science and Technology  Saratov Chernyshevsky State University  water purification 

Share |
PermalinkComments (0)
 

Is graphene the future of water filtration?

Posted By Graphene Council, The Graphene Council, Tuesday, February 19, 2019
Updated: Saturday, February 16, 2019

The National Graphene Institute (NGI) at The University of Manchester has signed an 18 month research project with LifeSaver, a UK-based manufacturer of portable and reusable water filtration systems.

The project will focus on developing graphene technology that can be used for enhanced water filtration, with the goal of creating a proprietary and patented, cutting-edge product capable of eliminating an even wider range of hazardous contaminants than currently removed by its existing high performance ultra-filtration process.

Graphene has emerged as a material with fantastic potential for water filtration and desalination in recent years, with researchers on graphene membranes at the NGI leading the way. Graphene was the first two-dimensional material ever discovered, it is also one of the strongest known natural materials in the world, while retaining high levels of flexibility, conductivity and filtration.

By incorporating graphene into its existing market leading water purification technology, LifeSaver hopes to reduce the sieve size of its hollow fibre filtration membrane from the current 15 nanometers (which effectively removes bacteria, microbial cysts and viruses) to about 1-3 nanometers. At that size, LifeSaver products could remove a much wider range of contaminants, such as heavy metals, pesticides, certain chemicals and potentially even nuclear radiation, from drinking water supplies.

“Making a graphene-based portable water filter was our dream, and this collaboration with LifeSaver will enable that dream to be a reality sooner than later,” said Professor Rahul Nair, who will lead the project at The University of Manchester. “This is a great example of a collaborative project where we are trying to combine two independently developed technologies into one, to enhance the quality and availability of drinking water for those who need it most.” 

Founded in the UK in 2007, LifeSaver came to life following back-to-back natural disasters: the Indian Ocean Tsunami and Hurricane Katrina to address the resulting need for access to clean drinking water. The first LifeSaver prototype was developed and became the world’s first portable water filter capable of removing the smallest known waterborne viruses. Since that time, LifeSaver has established itself as an effective and long-lasting solution to drinking water issues in the humanitarian sectors, and outdoor enthusiasts.

Tags:  Graphene  LifeSaver  National Graphene Institute  Rahul Nair  water purification 

Share |
PermalinkComments (0)
 

Who Will Win the Race for Clean Water Technologies Using Graphene?

Posted By Dexter Johnson, IEEE Spectrum, Monday, April 10, 2017

 

Image: University of Manchester

Graphene can take on at least three distinct technology approaches for producing clean water, according to Miao Yu, a professor at University of South Carolina and founder of UK-based G2O Water Technologies Ltd. as he explained to The Graphene Council last year in a interview.

In that interview, Yu said the first approach of the three is to use graphene in the creation of functional coatings. The second approach involves producing lamellar structures with nano-channels, which requires using fine layers of alternating types of materials. G2O Water is doing a bit of both of these approaches by creating a functional coating that can be applied to today’s polymer water membranes, and also creating scalable fabrication of lamellar structures of graphene oxide.

The third approach is to allow selective permeation through structural defects of single-layer graphene or graphene oxide. A group at MIT is probably the most notable example of the use of this approach in a technique they reported on three years ago. 

All of these approaches to using graphene in water applications is taking on increased interest after news came out last week that researchers from the University of Manchester have developed a graphene oxide membrane that in addition to filtering out small particles has small enough pores that it can filter out salt ions. This approach, which was published in the journal Nature Nanotechnology, falls into the approach taken by the MIT researchers.

The Manchester researchers have managed to overcome a key problem in this approach when the membranes swell up after being immersed in water for some time, allowing smaller particles to continue to pass through.

“Realization of scalable membranes with uniform pore size down to atomic scale is a significant step forward and will open new possibilities for improving the efficiency of desalination technology,” said Rahul Nair, a professor at the University of Manchester and one of the co-authors of the research, in a press release. “This is the first clear-cut experiment in this regime. We also demonstrate that there are realistic possibilities to scale up the described approach and mass produce graphene-based membranes with required sieve sizes.”

Of course, the imprimatur of the University of Manchester on anything to do with graphene suddenly makes this latest research noteworthy. However, the final arbiter on whether this graphene approach or the others like it for either desalinating or purifying water remains squarely on the industry.

While the mainstream press--like the BBC--has seemingly ignored all other efforts for using graphene in the desalination or purification of water--setting up the Manchester research as a kind of first in the field--the trade press has been a bit more circumspect.

The publication Water & Wastewater International (WWi) has a pretty thorough assessment of the latest Manchester research and how it stacks up to other efforts for desalinating water using graphene.

While WWi remains pretty sanguine about the general prospects of using graphene for water desalination, they get some expert opinions that characterizes this latest research as something of a long shot at this point.

Graeme Pearce, principal at Membrane Consultancy Associates (MCA) told WWi in an interview: "The development at the University of Manchester aims to produce a membrane with a highly controlled character, free from defects. Given the materials used, longevity should also be good. The challenge will be whether the membrane can be effectively used with the current form factor (the spiral wound element mounted in series in long pressure vessels) and using current process design concepts.

"Alternatively, the membrane might be better exploited by a completely different approach to process design, which would be high risk and slow to introduce, but might have a much greater long term impact if the improved membrane can be exploited more efficiently."

He added: "The key issue would be to demonstrate both performance and longevity in the first instance and then establish what features of the current approach to desalination plants limit the benefits of a new membrane and what can be done to remove these impediments."

It turns out that the technology of G2O Water technologies might have the inside track at this point, according to Pearce.

He added: "This preserves the form factor and should be more easily adopted by the industry. The development is still early stage and the longevity of the coating has yet to be established, but the approach appears to be promising and initial results on performance enhancement have been encouraging. This is more likely to allow a radical optimization of existing practice rather than the potentially more revolutionary but higher risk development from Manchester."

Tags:  G2O Water Technologies  graphene oxide  membranes  University of Manchester  water desalination  water purification 

Share |
PermalinkComments (0)