Ion exchange equilibria

Effective removal of cesium by pristine graphene oxide: performance, characterizations and mechanisms

“…12 Another way to compare the selectivity of the sorbent for any pair of cations is to compare the K d values of the two cations in a mixed binary cation solution. The ratio between their K d values is known as the separation factor, a A B ¼ K d,A / K d,B , between the two cations A and B in the solution 45,46 which yields directly the selectivity of GO for one cation as compared to the other cation given the same initial concentrations of A and B in the solution. The larger the separation factor indicates the more preference of the sorbent towards cation A compared to that of B.…”

“…It should also be noted that the selectivity order we observed here is also quite similar to the selectivity order of many polymeric cation-exchange resins, 51,52 whose selectivity order has also been explained based on the same trend of hydration radius and charge density of the hydrated cations as above. 46 In addition, the ether hole defects in GO sheet may also play important role in the observed selectivity of GO towards Cs cations. J. Guo et al have also shown that large hole defects on GO sheets can bind Cs + stronger than that of Na + or Li + .…”