Why direct or reversed Hofmeister series? Interplay of hydration, non-electrostatic potentials, and ion size.
A modified Poisson-Boltzmann analysis is made of the double layer interaction between two silica surfaces and two alumina surfaces in chloride electrolyte. The analysis incorporates nonelectrostatic ion-surface dispersion interactions based on ab initio ionic excess polarizabilities with finite ion sizes. A hydration model for the tightly held hydration shell of kosmotropic ions is introduced. A direct Hofmeister series (K > Na > Li) is found at the silica surface while the reversed series (Li > Na > K) is found at alumina, bringing theory in line with experiment for the first time. Calculations with unhydrated ions also suggest that surface-induced dehydration may be occurring at the alumina surface.
Parsons
D F
DF
Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia. Drew.Parsons@anu.edu.au
Boström
M
M
Maceina
T J
TJ
Salis
A
A
Ninham
B W
BW
D000537:Aluminum Oxide / Q000737:chemistry; D002712:Chlorides / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008672:Metals, Alkali / Q000737:chemistry*; D012492:Salts / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry; D055672:Static Electricity; D013499:Surface Properties; D014867:Water / Q000737:chemistry*
D002712:Chlorides; D004573:Electrolytes; D008672:Metals, Alkali; D012492:Salts; D014867:Water; D012822:Silicon Dioxide; D000537:Aluminum Oxide