Titanium, zirconium, and hafnium are present as cations in acid, so a strong acid cation resin like DOWEX™ G 26 (H) Resin is the separation media of choice. In dilute hydrochloric acid, Ti, Zr, and Hf have a high affinity for a strong acid cation resin. The affinity diminishes as the concentration increases from 4M to 8M HCl, but then the affinity increases again as acid concentration increases above 8M.
In perchloric acid, a strong acid cation resin has an even higher affinity for these cations.
In HF and HCl, these elements also form anions that can be captured on a strong base anion exchange resin like DOWEX 21K XLT Resin1.
Often these metals are separated from other closely associated metals so resins with the maximum number of theoretical plates are needed. Strong acid cation fine mesh resins are proposed for this separation, such as DOWEX 50WX8 100 200 Resin or DOWEX 50WX4 100 200 Resin.
1 "Resin Selectivity in Dilute to Concentrated Aqueous Solutions" by R.M. Diamond and D.C. Whitney, Chapter 8 of Ion Exchange – A Series of Advances Edited by J.A. Marinsky, Published by Marcel Dekker, Inc., New York (1966).