Breakthrough for lithium recovery

The design mimics biological ion channels and is claimed to show ‘remarkable efficiency and durability’ in separating lithium ions from magnesium ions in salt-lake brine. The study is detailed in Science Advances. 

The work introduces a "congener-welded" crystalline carbon nitride membrane with bio-inspired enhancements that outperforms traditional polymer membranes.

The membrane achieves a selectivity ratio of 1,708 for the extraction of highly dilute lithium ions (0.002M) from concentrated magnesium ions (1.0M), which addresses the high magnesium content in various sources of lithium.

The design of the membrane is inspired by highly selective biological ion channels, which discriminate between different ions.

In a statement Zhang Yuanyuan, co-first author of the study from QIBEBT, said: "Our approach was to mimic these natural systems, creating a membrane with both high selectivity and enhanced stability, which are critical for practical applications."

The performance of the membrane is due to its unique structure, which combines crystalline and amorphous forms of polymer carbon nitride. This structure provides pore uniformity and narrowness to exclude larger hydrated magnesium ions, but also facilitates lithium-ion transport, similar to the barrier-free ion transport seen in natural ion channels.