Crown ether-functionalized metal organic framework biomimetic nanochannels membrane for efficient Tl⁺ ion transport...

Fueled by the new energy revolution, the demand for lithium has soared beyond its supply, with lithium mining and smelting emerging as a crucial source. In this process, thallium-containing wastewater is produced, causing environmental pollution. In this work, inspired by the biological K⁺ ion channel, which preferentially transports Tl⁺ due to its similarity to K⁺, we constructed a conical single nanochannel (SCN) membrane modified with crown ether (4AB18C6) and MOF (UiO-66-(COOH)₂) for Tl⁺ ultrafast transport, instead of Li⁺. The 4AB18C6/MOF-MCN exhibited the Tl⁺ permeation rate of 5.72 mmol m^-2 h^-1 at low concentrations, with a Tl⁺/Li⁺ selectivity of about 30 in the binary system. The shape and charge properties of the SCN itself, along with its specific binding with 4AB18C6/MOF for fast Tl⁺ transport. The competitive inhibition arising from the difference of Tl⁺ and Li⁺ dehydration in a binary system further enhances the Tl⁺ ion selectivity. This work provides an efficient approach to excellent Tl⁺ transport and sieving capabilities, potentially inspiring further research on Tl pollution and resource recycling in the lithium industry.