Patent ID: 8173101

Claim:
A method for the removal of heavy metal ions from zeolite, the method comprising: (a) exposing the zeolite to a solution of hydrochloric acid enriched with ammonium salt that is sufficiently acidic to release exchangeable ions from the zeolite lattice; (b) neutralizing the zeolite; (c) exposing the zeolite to a plurality of ammonium salt solutions in a series of reactors to obtain a substantially complete replacement of exchangeable ions in the zeolite lattice by ammonium ions; (d) exposing the zeolite to a saturated calcium hydroxide and calcium chloride solution in a reactor to obtain a substantially complete replacement of the ammonium ions in the zeolite lattice by calcium ions; (e) decreasing the pH of the zeolite to a substantially neutral value; and (f) rinsing the zeolite with deionized water.