The invention is directed to ion capture devices and methods for ion capture.

Sorbent regeneration systems for use in dialysis machines are described. Sorbent regeneration cartridges may include a layer of urease, a layer of acid zirconium phosphate, and a layer of sodium zirconium phosphate. An apparatus for conducting dialysis may include a sorbent cartridge, and a dialyzer in fluid communication with the sorbent cartridge, wherein spent dialysate passes from the dialyzer to and through the sorbent cartridge, and wherein the sorbent cartridge comprises a layer of urease, a layer of acid zirconium phosphate, and a layer of sodium zirconium phosphate. The urease may be immobilized to or associated with a carrier.