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Separation of sulphides from pulping liquors by electrodialysis

  • US 5,536,384 A
  • Filed: 02/14/1995
  • Issued: 07/16/1996
  • Est. Priority Date: 02/14/1995
  • Status: Expired due to Term
First Claim
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1. A process for separating an alkaline aqueous sulphide-containing kraft pulping solution into a sulphide-rich solution and a sulphide-poor solution comprising:

  • i) feeding an aqueous sulphide-containing kraft pulping solution containing hydroxide ions, alkali metal ions and sulphide as hydrosulphide ions into a diluting compartment of a two compartment unit electrodialysis cell, said two compartment unit comprising said diluting compartment and a concentrating compartment, said diluting compartment being separated from said concentrating compartment by a monovalent anion-selective membrane,ii) feeding a liquid comprising water into said concentrating compartment,iii) passing a direct current through the electrodialysis cell to effect transfer of said hydrosulphide and alkali metal ions from said diluting compartment to said concentrating compartment, andiv) recovering a sulphide-rich solution from said concentrating compartment.

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