KIT developing lithium-ion sieve for geothermal lithium extraction
KIT’s IAM-ESS, in collaboration with several agencies, is developing a lithium-ion sieve and process for extraction of lithium from geothermal brine.
A research team from the Karlsruhe Institute of Technology (KIT) has published a paper in the Energy Advances journal that details the performance of a lithium-ion sieve material for the selective recovery of lithium from geothermal brine. Joining the researchers from KIT’s Institute for Applied Materials – Energy Storage Systems (IAM-ESS) in this project are Energie Baden-Württemberg AG (EnBW), the Fraunhofer Institute for Chemical Technology (ICT) , and Hydrosion GmbH.
The full paper “Lithium recovery from geothermal brine – an investigation into the desorption of lithium ions using manganese oxide adsorbents” can be viewed here: https://doi.org/10.1039/D2YA00099G
The lithium-ion sieve presented in the study is based on a lithium-manganese oxide ( Li1.6Mn1.6O4) with a special spinel-type structure. It was prepared via hydrothermal synthesis, where a substance crystallizes from an aqueous solution at high temperatures and pressures.
The research team tested the adsorption performance of the lithium-ion sieve using brine collected from the Bruchsal geothermal plant operated by EnBW in the Upper Rhine Graben in Germany. We had previously reported on the start of this collaborative project. Aside from being lithium-selective, the team also considered developing an adsorbent material that can be produced, used, and disposed on in an environmentally friendly manner.
Geothermal brine in the North German Basin had concentrations of up to 240 milligrams per liter, while those in the Upper Rhine Graben has up to 200 milligrams of lithium per liter. Despite the high concentrations, extraction is still a challenge because of the presence of many competing ions.
Desorption to release the lithium ions from the adsorbent was another major part of the study. Seven desorption solutions were tested, with acetic acid being singled out as the most effective in terms of lithium extraction and adsorbent preservation. However, the lithium-ion sieve was enriched with competing ions for all desorption tests, marginally reducing the sieve’s lithium adsorption capacity.
The next phase of this research will then involve a scale up from laboratory to pilot phase. There are still challenges in terms of handling the lithium-ion sieve, and maintaining an acceptable level of adsorption capacity during the process.
Source: KIT
