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Confining Water Inhibits Dissociation in Carbon Nanotubes

Confining Water Inhibits Dissociation in Carbon Nanotubes
Confining Water Inhibits Dissociation in Carbon Nanotubes

28/08/2018

 

One of the most fundamental processes in acid-base chemistry is the ionization of a water molecule forming the hydronium and hydroxide ions. The equilibrium between these ions and neutral water determines the dissociation constant of water (Kw) which in the bulk is 10-7. How this dissociation constant changes when water is near an interface or under confinement remains an open question. In this work, Damian Scherlis, a CMSP ICTP Associate and his student Yamila Perez Sirkin at the University of Buenos Aires and Ali Hassanali at ICTP teamed up to investigate how Kw changes for water under confinement within a carbon nanotube. Using ab initio molecular dynamics, they show that the Kw is reduced by three orders of magnitude implying that the presence of these ions in carbon nanotubes from spontaneous ionization is practically null. The origin of this is rooted partly in absence of water molecules to hydrate the ions. These results were published in The Journal of Physical Chemistry Letters (J. Phys. Chem. Lett., 2018, 9, pp 5029–5033).

 

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