Lithium, along with other cations, can be removed from water with a strong acid cation exchanger such as DOWEX™ G 26 (H) Resin. However, since lithium has a very low affinity compared to most other cations, leakage from the resin will occur ahead of the more attracted ionic species in the matrix. Lithium can only be selectively removed as an aluminum complex as described in the provided references1 2.
1 "Recovering Lithium from Brines" by Lee, John M. and Bauman, William C.; US Patent 4,347,327, August 31, 1982
2 "Regeneration of Crystalline Lithium Aluminates" by Burba, III, John L.; US Patent 4,472,362, September 18, 1984
List of Elements