At Res-Kem, we routinely get requests to remove specific cations or anions from water. Many of then I know, but there are many I do not. The first place I always look is on the Dow website. I believe Dow has the most creative way to navigate through the numerous Dowex and Amberlite resins they have available. They use the periodic table of elements to graphically show you what standard cation, standard anion or selective ion exchange resin might work. The problem is the chart is buried within the site and if someone at Dow hadn't shown me it years ago, I never would have thought to look for it.
Clearly, this is just the beginning. You will likely need to bench test and pilot test before any equipment should be purchased.
Important Links:
The Dow Product Selection Guide Via the Periodic Table
The Res-Kem Resin Equivalency Chart.