A new method improves the extraction and separation of rare earth elements — a group of 17 chemical elements critical for technologies such as smart phones and electric car batteries — from unconventional sources. New research led by scientists at Penn State and the Lawrence Livermore National Laboratory (LLNL) demonstrates how a protein isolated from bacteria can provide a more environmentally friendly way to extract these metals and to separate them from other metals and from each other. The method could eventually be scaled up to help develop a domestic supply of rare earth metals from industrial waste and electronics due to be recycled.
“In order to meet the increasing demand for rare earth elements for use in emerging clean energy technologies, we need to address several challenges in the supply chain,” said Joseph Cotruvo Jr., assistant professor and Louis Martarano Career Development Professor of Chemistry at Penn State, a member of Penn State’s Center for Critical Minerals, and co-corresponding author of the study. “This includes improving the efficiency and alleviating the environmental burden of the extraction and separation processes for these metals. In this study, we demonstrate a promising new method using a natural protein that could be scaled up to extract and separate rare earth elements from low-grade sources, including industrial wastes.”
Because the U.S. currently imports most of the rare earth elements it needs, a new focus has been placed on establishing a domestic supply from unconventional sources, including industrial waste from burning coal and mining other metals as well as electronic waste from cell phones and many other materials. These sources are vast but considered “low grade,” because the rare earths are mixed with many other metals and the amount of rare earths present is too low for traditional processes to work well. Furthermore, current methods for extraction and separation rely on harsh chemicals, are labor intensive, sometimes involve hundreds of steps, produce a high volume of waste, and are high cost.
The new method takes advantage of a bacterial protein called lanmodulin, previously discovered by the research team, that is almost a billion times better at binding to rare earth elements than to other metals. A paper describing the process appears online Oct. 8 in the journal ACS Central Science.
