Terbium can be used in technologies such as smart phones (to produce green colours on-screen), electric vehicle batteries and energy efficient lighting.

For this reason, a new method to extract it from toxic water sources could prove extremely valuable, according to Penn State professor and lead author of the study, Joseph Cotruvo Jnr.

“There is not currently a domestic supply chain of rare earth elements like terbium, but they are actually quite abundant in non-traditional sources in the U.S., including coal byproducts, acid mine drainage, and electronic waste,” he said.

“In this study, we developed a luminescence-based sensor that can be used to detect and even quantify low concentrations of terbium in complex acidic samples.”

The sensor uses a protein called lanmodulin which had been previously discovered.

The study found lanmodulin could attract rare earth elements almost one billion times better than it could attract other metals.

Cotruvo said the process of taking the sensor and applying it to water sources took advantage of natural processes

“One challenge with extracting rare earth elements is that you have to get them out of the rock,” Cotruvo said

“With acid mine drainage, nature has already done that for us, but looking for the rare earths is like finding a needle in a haystack.

“We have existing infrastructure to treat acid mine drainage sites at both active and inactive mines to mitigate their environmental impact.

“If we can identify the sites with the most valuable rare earth elements using sensors, we can better focus extraction efforts to turn waste streams into revenue sources.”

Further research plans to enhance the sensor and learn how to attract other rare earths elements.