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Scientists fight toxic "forever" chemicals



The day Susan Gordon learned that Venetucci Farm in Colorado was contaminated by toxins, the vegetables looked as good as ever, the grass was so green, and the cattle, pigs, chickens, and goats were so healthy.

The beauty of the community farm that she and her husband ran made the disclosure all the more tragic. Invisible and insidious chemicals known as per- and polyfluoroalkyl substances had spoiled the groundwater under their feet. PFAS had penetrated the ground after decades of training drills that sprayed fire-fighting foam onto nearby Peterson Air Force Base, Colorado Springs. The danger became clear when the US Environmental Protection Agency issued a health recommendation in 201

6 that recommended that drinking water be kept below the limit values ​​of two common types, PFOA and PFOS. Although the Air Force provided filters, the farm was closed in December 2017.

PFAS was originally a symbol of the American spirit of invention and was designed as a miracle cure that could resist stains, repel water, extinguish terrible oil-based fires and keep eggs from sticking to the pan. Today we know it as a Frankenstein-like invention, zombie chemicals that won't die.

Chemists have made thousands of such compounds by binding carbon to fluorine in chemical chains, thus forging one of the strongest bonds ever discovered. Now they have been found all over the world – even in the blood of arctic foxes and polar bears. Public health studies have shown that approximately 95 percent of Americans have PFAS in their blood. While the health effects of low exposure levels are less clear, the chemicals are related to liver, thyroid and immune effects, cancer and low birth weight. Removing PFAS from drinking water and the environment will require billions of dollars – and even more technical skills. The task seems bleak, even though the U.S. Department of Defense is willing to spend more than $ 2 billion on PFAS rehabilitation at its bases. Fire brigade training centers, airports and industrial sites also make a major contribution.

On Friday, the US House of Representatives passed the PFAS Action Act, which requires the EPA to set drinking water limits for two PFAS (PFOA and PFOS) to label PFAS chemicals as hazardous substances under the Superfund cleaning program. Your way forward is uncertain. Even though the Senate passed the measure, the Trump administration has described its provisions as "problematic and unreasonable" and threatened to veto this. This means that the compounds known as "forever" chemicals can at least be removed from groundwater , "I actually felt a little bit of hope," says Chris Higgins, environmental engineer at the Colorado School of Mines and PFAS expert. "We are getting some technologies that seem to be working."

The most promising approach is an electrical response that looks like lightning strikes water. Contaminated water passes through a plasma reactor in which argon gas presses the PFAS connections to the surface. Electrodes above and below the surface generate plasma – a highly reactive gas made up of positive ions and free electrons – that interacts with the PFAS and breaks the carbon-fluorine bonds.

"Our goal is to completely destroy the connection, not just move it from one phase to another," said Michelle Crimi, an environmental engineer at Clarkson University in Potsdam, New York. She is working on new technologies for the rehabilitation of PFAS. The technology of the plasma reactor was developed by her colleagues Selma Mededovic, chemical engineer, and Tom Holsen, environmental engineer.

Crimi also uses ultrasound waves to create voids – essentially holes – in the water. When they collapse, they trigger physical and chemical reactions that break the PFAS chains. Other researchers are working on electrochemical techniques and even soil bacteria that can metabolize PFAS.


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