TH99455A - Method for electrochemical removal of chlorine in brine anolite from electrolysis of NaCl. - Google Patents

Abstract

DC60 (18/04/51) A method for subsequent conditioning of a NaCl solution by reduction. This method involves preparing a NaCl solution from the anode of the electrolytic NaCl cell, containing reducing components, and then reducing this solution using an electrochemical process at the cathode.

Claims (20)

1. The method involves preparing a solution containing NaCl, which serves as the anode for electrolytic NaCl decomposition. This solution contains reducing components, and the solution is then reduced electrochemically at the cathode. 2. The method under claim 1, as previously described, involves adjusting a solution containing NaCl with hydrogenated carbon. 3. Method according to claim 2, where the NaCl solution is conditioned with hydrogen sulfide before reduction by electrochemical process at the cathode. 4. Method according to claim 2, where a solution containing NaCl is conditioned with hydrogen sulfide before electrochemical reduction at the cathode. 5. The method under claim 1, as previously described, involves conditioning a solution containing NaCl with a hydrogen sulfide solution containing water. 6. The method under claim 5, whereby a solution containing NaCl is conditioned with an aqueous hydrogen sulfide solution before reduction by an electrochemical process at the cathode. 7. The method under claim 5, where a solution containing NaCl is obtained and adjusted with an aqueous hydrogen sulfide solution after reduction by an electrochemical process at the cathode. 8. The method under Claim 1 where the electrochemical reduction at the cathode is carried out in a cell with anode and cathode compartments separated by a membrane or ion-exchange septum. 9. The method under Claim 1, where the electrochemical reduction at the cathode is carried out galvanostatically. 10. The method under Claim 1, where the electrochemical reduction at the cathode is carried out in a potentiostatic manner. 11. The method under Claim 1 where electrochemical reduction at the cathodes is carried out by the anodes, and each cathode is independently composed of materials selected from a group consisting of carbon, carbon-graphite, graphite and titanium coated with noble metals and noble metal oxides. 12. Method according to claim 1, whereby the cathodic electrochemical reduction of a reducing component carried out in an electrochemical cell containing an anode and a cathode chamber, an anode reaction occurs in the anode chamber, in which such anode reaction is selectively chosen from groups consisting of chlorination, oxygen production, oxidation of iron (II) chloride to iron (III) chloride, and a combination of these. 13. The method under Claim 1 where electrochemical reduction at the cathode is carried out using a cathode with an internal surface area and an external geometric surface area such that the internal surface area is larger than the external geometric surface area. 14. The method under claim 13, where the area of such interior surface is at least twice the area of such exterior geometric surface. 15. The method under Claim 1, whereby the cathodic electrochemical reaction is carried out in a cathode-containing electrolytic cell and whereby a solution containing NaCl has a duration in the cathode-containing chamber of 1 to 30 minutes. 16. The method under claim 15, where the NaCl solution has a residence time in the cathode chamber of 1 to 10 minutes. 17. The procedure under Claim 1, whereby the electrochemical reaction at the cathode is carried out with a current intensity of 5 to 100 amperes/square meter. 18. Method according to claim 1 where an electrochemical reaction at the cathode is carried out with a discharge rate of 0.05 to 0.5 Ah/L, where the NaCl solution contains approximately 100 mg/L of chlorine. 19. The method under Claim 1, whereby at least 80% of the reducing components are reduced by electrochemical reduction at the cathode. 20. The method under Claim 1, where at least 80% of the reducing compounds are reduced by a combination of electrochemical reducing processes at the cathode, and the remaining compounds to be reduced are modified by a chemical reducing process by adding a sulfur-containing reducing agent.