Reviewed by Lexie CornerSep 26 2024
A research team led by James Tour of Rice University has developed a more efficient method for recycling valuable metals from electronic waste, significantly reducing the environmental impact typically associated with metal recycling. This study was published in Nature Chemical Engineering.
James Tour, left, and Shichen Xu, right. Image Credit: Gustavo Raskosky/Rice University.
Recycling metals can reduce the need for mining, thereby mitigating the environmental damage caused by raw material extraction, such as greenhouse gas emissions, deforestation, and water pollution.
Our process offers significant reductions in operational costs and greenhouse gas emissions, making it a pivotal advancement in sustainable recycling.
James Tour, T.T. and W.F. Chao Professor, Chemistry and Materials Science and Nanoengineering, Rice University
Innovative Technique
The new technique enhances the recovery of critical metals. It builds on Tour's previous work with flash Joule heating (FJH), a method that rapidly heats materials using electric current, converting them into various substances.
The researchers employed FJH chlorination and carbochlorination processes to extract valuable metals like gallium, indium, and tantalum from e-waste. Unlike traditional recycling methods such as hydrometallurgy and pyrometallurgy—which are energy-intensive, generate hazardous waste, and require large amounts of acid—this new approach allows precise temperature control and rapid metal separation without using water, acids, or other solvents, greatly reducing environmental impact.
We are trying to adapt this method for recovery of other critical metals from waste streams.
Bing Deng, Study Co-First Author and Assistant Professor, Tsinghua University
Efficient Results
The researchers found that their technique effectively extracts indium from used solar conductive films, gallium from discarded light-emitting diodes, and tantalum from capacitors. By precisely controlling the reaction conditions, they achieved yields of over 85 % and metal purities exceeding 95 %.
Shichen Xu, a postdoctoral researcher at Rice University and co-first author of the study, noted that the method also holds potential for extracting lithium and rare Earth elements.
This breakthrough addresses the pressing issue of critical metal shortages and negative environmental impacts while economically incentivizing recycling industries on a global scale with a more efficient recovery process.
Shichen Xu, Study Co-First Author and Postdoctoral Researcher, Rice University
Jaeho Shin, Yi Cheng, Carter Kittrell, Justin Sharp, Long Qian, Shihui Chen, and Lucas Eddy of Rice’s Department of Chemistry and Khalil JeBailey of Rice’s Department of Materials Science and NanoEngineering are the other study authors.
The Defense Advanced Research Projects Agency, U.S. Army Corps of Engineers, Rice Academy Fellowship, and startup funds from Tsinghua supported the study.
Journal Reference:
Deng, B., et. al. (2024) Flash separation of metals by electrothermal chlorination. Nature Chemical Engineering. doi.org/10.1038/s44286-024-00125-2