Ratchet-Based Ion Pumps for Selective Ion Separations

Alon Herman, Joel W. Ager, Shane Ardo, Gideon Segev

Research output: Contribution to journalArticlepeer-review


The development of a highly selective, membrane-based ion separation technology could significantly improve the sustainability and energy efficiency of water treatment technologies and emerging applications, such as electrochemical
reduction, extraction of valuable metals from seawater, and battery recycling. In this work, we show through computational modeling that an electronic flashing ratchet mechanism can be used for high-precision ion separation. The suggested ratchet-based ion pumps utilize a unique feature of electronic ratchets, frequency-dependent current reversal, to drive ions with the same charge, but different diffusion coefficient, in opposite directions. The model shows that ions whose diffusion coefficients differ by as little as 1% can be separated by driving them in opposite directions with a velocity difference as high as 1.2 mm/s. Since the pumping properties of the ratchet are determined by a time-varying electric input signal, the proposed ion pumps could be instrumental in realizing an efficient, large-scale, and fit-for-purpose system for selective ion separation. Examples of ratchet-driven systems for lithium extraction from seawater, lead removal from drinking water, and water desalination are discussed and analyzed.
Original languageEnglish
Article number023001
Number of pages18
JournalPRX Energy
Issue number2
StatePublished - 1 Apr 2023


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