||Removal of metal ions in water for industrial use, called water softening, is an important procedure since ions cause significant problems with maintenance of equipment. Even though ion exchange and chelate resins are widely used for desalination, they have some limitations with regeneration condition. In this research, sulfonamide-derived cation capturing system is suggested as an alternative to relieve these drawbacks. Sulfonamide derivatives show a sharp transition from charged to uncharged form at certain pH, which alleviates the condition of regeneration. Four types of sulfonamide derivatives were selected as candidates in our research and introduced on the surface of polystyrene microbeads. The surface modification was confirmed by FT-IR analysis, and their calcium ion capturing capacities in actual circumstances were verified. Finally, the most regenerative type of sulfonamide in the moderate acidic condition was determined through regeneration test.