Temperature effect on ion selectivity of potassium and sodium ions in solution

•Using molecular dynamics simulation we study the ion selectivity of various diameter nano-pores, and find that the selectivity of membranes can be enhanced through decrease of temperature.•This carries important implications for the enhancement and control of selectivity.•The variation of the ion hydration shells and cation-anion interactions with temperature affects the ability of ions to access nanopores.•Higher temperature makes ion selectivity vulnerable.

The effect of temperature on ion selectivity of various-diameter nanopores in an NaCl and KCl solution has been studied with molecular dynamics simulation. Our results indicate that ion selectivity is absent at high temperature, while pores become increasingly selective as the system temperature decreases, but that depends on the nano-pore diameter. By investigating how the hydration shell of ions and cation-anion interactions affect the ability of ions to access the nanopore, we reveal the mechanism behind this dependence of selectivity on temperature. The implication that ion selectivity is vulnerable to higher temperature may provide a useful selectivity-control mechanism, and may help improve the performance of permeable membranes.

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