Graphene Membranes Offer Energy-Efficient Water Purification
A promising technology that has emerged in recent years is the use of graphene in water purification. Graphene is a single layer of carbon atoms arranged in a hexagonal lattice and has unique properties that make it an ideal material for filtering and purifying water. It is incredibly strong, lightweight, and flexible, with a large surface area and excellent conductivity. Graphene-based membranes have been shown to enable more efficient water filtration with less energy input, making them a more sustainable option for large-scale desalination projects. Graphene’s flexibility and durability mean that it can be easily incorporated into existing water-treatment systems or used to create portable, low-cost filtration devices.
Chlorinated Chemicals Can Be Destroyed Through Sulfite and
The University of California, Riverside (UCR) researchers have discovered a chemical reaction mechanism that can degrade chlorinated PFAS into harmless substances. The researchers employed UV light and sulfite to break chlorine-to-carbon bonds and carbon-to-carbon and carbon-to-fluorine bonds, crucial for the quick and near-complete defluorination of PFAS compounds. The UCR team is investigating additional methods and mechanisms for PFAS degradation, and its ultimate objective is to break all carbon-fluorine bonds to detoxify PFAS contaminants.
New Method May Break Down PFAS on Water-Treatment Filters
Feng Xiao and colleagues at the University of Missouri have created an innovative method using thermal induction heating to rapidly break down PFAS left on the surface of two solid materials, granular activated carbon and anion exchange resin, after these materials have been used to filter PFAS from municipal water systems. While PFAS can be filtered out of water using adsorbents, the disposal of used adsorbents creates issues of environmental contamination. Xiao, who has spent his career focused on researching ways to safely remove PFAS from the environment, recently demonstrated efficiency with the use of induction heating to rapidly degrade PFAS in soil. Potential drawbacks of this method include byproducts created during the process, but Xiao suggests that some of these products can be degradable by regular thermal approaches.
Pressure-Driven Distillation Using Air-Trapping Membranes
A new water-desalination technology uses applied pressure to drive vapor transport through membranes with an entrapped air layer. Since separation occurs due to a gas-liquid phase change, near-complete rejection of dissolved solutes, including sodium chloride, boron, urea, and N-nitrosodimethylamine is observed. Membranes fabricated with sub-200-nm-thick air layers showed water permeabilities that exceed those of commercial membranes without sacrificing salt rejection. The air-trapping membranes tolerate exposure to chlorine and ozone oxidants. The results advance the understanding of evaporation behavior and facilitate high-throughput, ultraselective separations.
Scientists at the Johns Hopkins University Applied Physics Laboratory (APL) have made progress in developing better ways to remove and destroy PFAS in municipal and household water systems. APL scientists have adapted an inexpensive, off-the-shelf membrane that allows water to pass but captures destructive chemicals with “whiskers,” or fibers added to the surface and made of a synthetic element engineered at APL. The new membrane can be made into a quarter-size filter for a home faucet or a sheet to cover a large municipal water system. APL scientists are also researching ways to break down PFAS into minerals that are safe to throw away in the trash, as well as creating new chemicals that do the same job as PFAS but aren’t harmful to the planet and living beings.
Electrified Dialysis for Desalination Cuts Cost and Energy Expenses
Researchers at the Beckman Institute for Advanced Science and Technology have developed an electrified version of dialysis to separate salt and other unnecessary particles from potable water. Xiao Su and his colleagues used a modified version of electrodialysis to remove salts and organic matter from wastewater to produce a clean, drinkable product. To save energy, the researchers streamlined the salt separation process with a chemical phenomenon called a redox reaction, which changes the charge of the entire water molecule in one fell swoop, achieving the same degree of salty separation with about 90 percent less energy than traditional water-splitting. To add economic savings, the researchers swapped conventional ion-exchange membranes for a nanofiltration membrane, a more robust and less expensive option.
Catalyst-Based Method Kills Bacteria, More Effective Than Chlorine
Researchers from Cardiff University have teamed up with Origin Aqua to develop a product that disinfects water, kills viruses and bacteria, and removes chlorine byproducts. Cardiff Catalysis Institute (CCI) researchers found that a catalyst made from gold and palladium takes in hydrogen and oxygen to form hydrogen peroxide—a commonly used disinfectant currently produced on an industrial scale. The catalyst-based method was shown to be 10,000,000 times more potent at killing bacteria than an equivalent amount of industrial hydrogen peroxide, and over 100,000,000 times more effective than chlorination, under equivalent conditions. The innovation project, led by CCI, is a finalist in the Water Discovery Challenge, run by Challenge Works and the Water Services Regulation Authority, Ofwat, with Arup and Isle Utilities.
Sandia Scientists Achieve Breakthrough in Tackling PFAS Contamination
A team at Sandia National Laboratories is developing materials to tackle human exposure to PFAS through contaminated water and other products. Sandia chemist Andrew Knight has been working with Ryan Davis, who specializes in materials science, to create a filter that could not only eliminate PFAS in water on a large scale but also in a household setting. With $100,000 in recently awarded funds from the Sandia Technology Maturation Program, the team hopes to build its data to show how well the materials work. The goal is to commercialize the product to remove 99 percent of PFAS from water.
Applying Iron Oxide Nanoparticles to Arsenic Removal
Iron oxide nanoparticles offer a promising sustainable solution to arsenic contamination in water sources with their high surface areas and reactivity, which makes them effective at absorbing and removing arsenic. Iron oxide nanoparticles work by adsorbing arsenic onto their surface, which is then removed from the water through filtration. Iron oxide nanoparticles provide a sustainable solution for water purification; they are effective at removing arsenic from water and relatively easy to synthesize and modify, making them a cost-effective and scalable solution for developing countries. They are also environmentally sustainable—they do not produce any harmful byproducts or generate waste.
‘Predatory’ Bacteria Could Replace Chlorine as Effective Water Purifier
Chlorine has long been used as an effective way to remove microorganisms from drinking water, but it has been linked to health problems. In a new study, researchers looked at how bacteria responded when chlorine was removed from the water-purification process. Researchers from Lund University tested how removing chlorine affected the bacteria that grew in the water system in the city of Varberg, Sweden. Three months after chlorine was removed from the water system, the researchers found that certain bacteria had significantly reduced in number, except for one—Bdellovibrio, which is known to prey on other bacteria. Researchers now want to know what effect those bacteria that grow in drinking water after chlorine has been removed would have on humans. Ultimately, the researchers found that using bacteria as an alternative to chlorine might present a less costly, more energy-efficient way to purify drinking water.