Recovery of mixed acids from mixed salts

  • US 4,999,095 A
  • Filed: 05/16/1988
  • Issued: 03/12/1991
  • Est. Priority Date: 05/03/1985
  • Status: Expired due to Fees
First Claim
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1. A process for recovering a mixed acid solution comprising hydrofluoric acid from a solution comprising salts of the acids to be recovered comprising the steps of:

  • (a) providing an electrodialytic water splitter comprising at least two unit cells, each unit cell comprising a means for splitting water comprising a bipolar membrane or spaced apart anion and cation membranes, a first compartment and a second compartment, said electrodialytic water splitter additionally comprising a single pair of anode and cathode electrodes said at least two unit cells being between the anode electrode and the cathode electrode;

    (b) feeding an aqueous solution comprising at least two salts formed from at least two different anions to the first compartment, one of said anions being fluoride anions;

    (c) feeding a liquid comprising water to the second compartment;

    (d) passing current through said electrodialytic water splitter to produce an aqueous product comprising mixed acids formed from the different anions in the second compartment, and an aqueous salt-containing product comprising a reduced concentration of said anions in the first compartment; and

    (e) recovering aqueous product comprising hydrofluoric acid from the second compartment.

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