Poisonous heavy metals contaminating thousands of sites nationwide threaten to enter the food chain, and there’s been no easy way to remove them. An experimental chemical bath and electrochemical filter could now extract heavy metals from the soil and leave fields safe.
When poisonous heavy metals like lead and cadmium escape from factories or mines, they can pollute the nearby soil. With no easy ways to remove these contaminants, fields must be cordoned off to prevent these toxins from entering the food chain where they threaten human and animal health.
According to the Environmental Protection Agency, heavy metals have been found at thousands of locations nationwide. While some have been cleaned up through a combination of federal, state and private efforts, the need remains for new technologies to address heavy metal contamination.
Now a research team led by Stanford materials scientist Yi Cui has invented a way to wash heavy metals from contaminated soils using a chemical process that’s a bit like brewing coffee.
As they describe June 4 in Nature Communications, the researchers started by rinsing contaminated soil with a mixture of water and a chemical that attracts heavy metals. When that mixture percolates through the soil, the chemical pulls heavy metals loose. The team members then collected this toxic brew and ran it through an electrochemical filter that captured the heavy metals out of the water. In this way they cleansed the soil of heavy metals and recycled the water and chemical mixture to percolate through more contaminated ground.
“This is a new approach to soil cleanup,” said Cui, who is a professor of materials science and engineering and photon science. “Our next step is a pilot test to make sure that what works in the lab is practical in the field, and to figure out how much this process will cost.”
So far, his team has cleansed soils contaminated with lead and cadmium, two prevalent and dangerous toxins, as well as with copper, which is only dangerous in high concentrations. Cui believes this process of chemical cleansing and electrochemical filtering will work with other dangerous heavy metals like mercury and chromium, but further lab experiments are needed to demonstrate that.
No more sacrificial plants
Cui said the project began two years ago when he and graduate student Jinwei Xu brainstormed about how to solve the basic problem: Heavy metals bind to the soil and become virtually inextricable. Today, Cui said, cleanup may involve digging up contaminated soils and sequestering them somewhere. Agricultural researchers have also developed phytoremediation techniques – growing sacrificial plants in contaminated soil to absorb heavy metals, then harvesting these crops and taking them to an extraction and disposal facility. But phytoremediation can take many years of repeated harvests.
Seeking a quick, cost-effective way to extract heavy metals from contaminated fields, the researchers tried washing toxic soil samples with plain water. They soon realized that plain water couldn’t break the chemical bond between the heavy metals and the soil. They needed some additive to pry the contaminants loose. They found the answer in a common chemical known by its initials: EDTA.
In retrospect, EDTA was the obvious choice because this same chemical is used to treat patients poisoned with lead or mercury. Negatively charged EDTA bonds so strongly to positively charged heavy metal particles that it pulls the lead or mercury from the patient’s tissues. The researchers reasoned that, when dissolved in water, EDTA’s negative hooks would rip heavy metals loose from soils. Experiments bore this out. When EDTA-treated water percolated through contaminated soil, it carried the heavy metals away.
But the team’s job was only half done. The soil was clean, but the treated water was still toxic. They needed a way to separate the EDTA from the heavy metals in the rinse water and capture those toxins once and for all.
Isolating heavy metals
The scientists knew that EDTA remained strongly negative even after it captured a positively charged metal particle. So, the researchers built a sieve with the electrical and chemical properties to pull the negatively charged EDTA and positively charged heavy metals apart. The result was isolated heavy metals and a mixture of water and EDTA ready to purify more soil.
In addition to lead and cadmium, the researchers tested the process on copper, which is only dangerous in high concentrations. Next Cui would like to run the experiment on other heavy metals like mercury, which are so toxic they require special handling to protect the researchers. But he thinks the chemistry is so sound that he is confident of success in the lab. The bigger question is whether the process can be scaled up to treat tons of contaminated soil. The researchers have sought to patent the process through the Stanford Office of Technology Licensing and would like to find an opportunity to run a pilot project in a contaminated field.
“We really have no good remediation technology for heavy metals,” Cui said. “If this proves practical on a large scale it will be a significant advance.”
The Latest on: Heavy metals
via Google News
The Latest on: Heavy metals
- Mitsubishi Power Concludes Licensing Agreement with Aubert & Duval, Leading Manufacturer of Additive Manufacturing Metal Powderson November 27, 2020 at 8:27 am
Development and manufacturing base established at Mitsubishi Power Hitachi Works- New business to emerge applying proprietary ...
- Beached Whales, Dolphins on US Coast Had High Levels of Pollutants, Heavy Metalson November 26, 2020 at 10:40 pm
For the first time, scientists detected the widely used antibiotic Triclosan and the popular herbicide Atrazine in rare species that spend their lives hundreds of kilometres offshore.
- Heavy metal: Myrtle Beach cops say man stole 1,200lbs of copper from his former employeron November 26, 2020 at 6:01 pm
Earlier this month, officers went to Waccamaw Metal Recycling on Stockholder Avenue for the reported theft. Police learned a person took copper from the property and that Chestnut, a former employee, ...
- Cows Exposed to Heavy Metals Worsen Antibiotic Resistance Crisison November 26, 2020 at 9:18 am
Fundao Tailings Dam failure in Brazil, researchers analyzed the consequences of long-term exposure to contaminated drinking water on dairy cattle ...
- Heavy Metal movie star vs. actual stars and planets in Taarna #1 previewon November 24, 2020 at 8:33 am
"From the death of the last Taarakian and a collapsed universe, Taarna was born. Heavy Metal's flagship character from the animated film returns in a new series of cosmic mystery and battles ...
- ‘Sound of Metal’ director Darius Marder reveals how his heavy metal drama starring Riz Ahmed came to beon November 20, 2020 at 2:00 pm
Darius Marder was helping his friend, “I Know This Much Is True” director Derek Cianfrance, on a film about a real couple in a metal band. When Cianfrance, with whom Marder would write “Place Beyond ...
- ADA Claims Are Cut From American Airlines Heavy Metals Suiton November 20, 2020 at 1:48 pm
An Oklahoma federal judge has trimmed Americans with Disabilities Act claims from a proposed class action alleging American Airlines Inc. exposed workers to heavy metals then subjected them to ...
- The Definitive Heavy Metal Holiday Gift Guide 2020on November 20, 2020 at 11:36 am
Hanukkah and Kwanza shopping for metal heads may not be easy, so we have a few suggestions. We can all agree that 2020 will go down in the history books. A year like no other, but it seems like the ...
- Heavy Metal Military Thunder: Meet the American Military Motorcycleon November 17, 2020 at 3:19 am
The motorcycle still provides transportation for soldiers today. A big part of the global war on terror meant going to places where teams need to get in and out fast, and that included remote ...
- Heavy Metal Pioneer Jonny Z Talks Jersey Roots, Metallica’s Early Days in New Audiobookon November 16, 2020 at 6:52 pm
Heavy metal titan and founder of Megaforce Records/Crazed Management Jonny Zazula — best known in metal circles as Jonny Z — is tantamount for giving a voice and a platform to what was ...
via Bing News