Researchers from Australia and the U.S. have developed an efficient approach for extracting lithium and other minerals from seawater. The technique uses metal-organic-framework (MOF) membranes that mimic the filtering function, or ion selectivity, of biological cell membranes. The membrane process easily separates metal ions as well as salts from seawater, offering scope for advanced technologies benefitting the water and mining sectors.

In desalination applications, the zeolitic imidazolate framework (ZIF) membranes consume far less energy relative to the reverse osmosis systems now widely deployed. Their use is also envisioned in direct extraction and purification of lithium from salt water and waste process streams.

The Barnett and Eagle Ford shale formations in Texas contain high amounts of lithium, and the produced wastewater generated by hydraulic fracturing in those areas has high concentrations of lithium. Instead of discarding the produced water, the membrane filter could extract the resulting lithium and put it to use in other industries.

Each well in the Barnett and Eagle Ford can generate up to 300,000 gallons of produced water per week. Using their new process, the researchers conservatively estimate that from just one week’s worth of produced water, enough lithium can be recovered to power 200 electric cars or 1.6 million smartphones.

Scientists from the University of Texas at Austin, Monash University (Australia) and the Commonwealth Scientific and Industrial Research Organisation in Australia participated in this research, which is published in the journal Science Advances.

Schematic illustration of ion transport through a ZIF membrane with ~3.4 Å pore windows for ion selectivity and ~11.6 Å pore cavities for fast ion transport (drawing not to scale). The inset indicates the crystal structure of ZIF. Source: Science Advances