A clean way extract rare earth metals

A clean way to extract rare earth metals

9:58 AM, 24th June 2016
A clean way to extract rare earth metals
Rare earth metals are used in everything from wind turbines to cell phones,electric cars and precision weapons.

CAMBRIDGE, US: Rare earth metals — those 17 chemically similar elements at the bottom of the periodic table — are in almost every piece of technology we use from cell phones to wind turbines to electric cars. Because these elements are so similar to each other, the process of separating them is time consuming, expensive, and dangerous. Processing one tonne of rare earths can produce 2,000 tonnes of toxic waste.

Now, researchers from the Harvard John A Paulson School of Engineering and Applied Sciences (SEAS) have found a clean alternative.

As part of their research at SEAS, from 2009 to 2015, David Clarke, the extended tarr family professor of materials, and his then graduate student, William Bonificio, have developed a method to separate rare earths using bacteria filters and solutions with pH no lower than hydrochloric acid.

The method was described in the journal Environmental Science and Technology Letters.

Harvard's office of technology development has filed patents and is actively pursuing commercial opportunities.

“Rare earths are very desirable but only if you can separate them,” said Clarke. “It’s a big 'if' because how can you separate ions that are almost the same size and the same charge?”

Current separation methods involve hundreds of steps and lots of hazardous chemicals.

Clarke and Bonifico found inspiration in the living world of bacteria. Bacteria filters have long been used to bio-absorb toxic elements from wastewater or filter metals from mine drainage systems. Recent research showed that some rare earths can bioabsorb, but Clarke and Bonifico wondered if all rare earths could be filtered through bacteria.

They immobilized the bacteria from marine algae on an assay filter and passed a solution of mixed rare earths (known as lanthanides) through it. The bacteria bio-absorbs all the elements as they passed — plucking them out of the solution and fixing them to their surface.

Then the team pumped solutions of various pH balances through the filter. With each successive pH wash, different rare earths detached. The researchers found that lighter lanthanides, such as europium and praseodymium, desorbed with higher-pH washes while heavier lanthanides, such as thulium, lutetium, and ytterbium, desorbed with lower pH.

The team also found that if they wanted to separate only the heaviest metals, such as Thulium, which is commonly used in lasers and portable X-rays, they could block the bacteria’s receptors that absorb the lighter rare earths and only use a low-pH solution.

“We found that it is possible to concentrate a solution of equal concentrations of each lanthanide to nearly 50 percent of the three heaviest lanthanides in just two passes,” said Bonificio. “This surpasses existing industrial practice.”

“This is a radically different way of doing separation,” said Clarke. “We have an opportunity to harness the diversity of bacterial surface chemistry to separate and recover these valuable metals in a way that is environmentally benign.”  

This research was supported by the Harvard University Center for the Environment and the Office of Naval Research.

© Harvard University News

0 Comments

Login

Your Comments (Up to 2000 characters)
Please respect our community and the integrity of its participants. WOC reserves the right to moderate and approve your comment.

Related News


New cheap, complementary method for chemical reaction developed

PRINCETON, US: A team of researchers at Princeton University, the Massachusetts Institute of Technology (MIT) and Merck & Co has developed a cost- ...

Read more
Clariant acquires Carboflex consortium full control in Brazil

MUTTENZ, SWITZERLAND: Clariant International Ltd has acquired full stake from Carboflex in the consortium that built and operates the Guanabara Bay pl ...

Read more
BASF, Kingenta partner for fertilizers in China

LINSHU, CHINA: BASF SE has entered into strategic partnership agreement with Chinese fertilizer supplier Kingenta Ecological Engineering Group Co Ltd ...

Read more
Henkel opens new composite lab in Germany

DUSSELDORF, GERMANY: Henkel AG & Company has opened its new state-of-the-art composite test lab in Heidelberg, Germany. Here automotive customers ...

Read more
Umicore opens new emission control catalysts plant in Poland

BRUSSELS, BELGIUM: Umicore NV has officially opened its new production plant for emission control catalysts in Nowa Ruda, Poland (near Wroclaw). The f ...

Read more
BASF, Aspen extend partnership to develop next generation building materials

LUDWIGSHAFEN, GERMANY/ NORTHBOROUGH, US: BASF SE and Aspen Aerogels Inc (Aspen) has expanded their strategic partnership with the signing of an exclus ...

Read more