Does cation dehydration drive the binding of metal ions to polyelectrolytes in water? What we can learn from the behaviour of aluminium(III) and chromium(III).

Much stronger binding is seen in aqueous solutions between the anionic polyelectrolyte potassium poly(vinyl sulfate) and the substitution labile aluminium(III) than with the kinetically inert chromium(III). This strongly supports the idea that entropy driven water loss from the hydration sphere of the metal ion plays a major role in driving binding of the trivalent metal ion to the polyelectrolyte.