Method for continuous measurement of the sulfite/sulfate ratio

• US 4,533,440 A
• Filed: 08/04/1983
• Issued: 08/06/1985
• Est. Priority Date: 08/04/1983
• Status: Expired due to Fees

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Kim, Bang M.
• Primary Examiner(s): Metz, Andrew H.
• Assistant Examiner(s): Nguyen, Nam X.
• Application Number:
  US06/520,389
• Time in Patent Office: 733 Days
• Field of Search: 204/1 F, 204/1 T, 204/400, 204/435, 204/92
• US Class Current: 205/782.5
• CPC Class Codes: B01D 53/346 Controlling the process
• CPC Class Codes: B01D 53/504 characterised by a specific device

Abstract

The redox potential is used as a measure of the ratio of sulfite and sulfate ions in a solution containing these ions. In one embodiment of the present invention a slip stream sample of a process solution is divided into two components one of which is oxidized to serve as a reference solution. The ratio of sulfite and sulfate ions or the oxidation state of the solution is indicated by the oxidation potential of a process solution or the potential difference between electrodes disposed within a process solution and a reference solution.

Claims

1. A method to monitor the ratio of sulfite ion species concentration to sulfate ion species concentration and the rate of change thereof in a solution containing said species, said method comprising the steps of:

supplying at least a portion of said solution containing said sulfite and said sulfate ion species to a vessel in which there is disposed a redox electrode and a reference electrode so that both said electrodes are in contact with said solution;

determining the electrical potential difference, V₁, between said electrodes;

simultaneously with said supplying step, oxidizing a portion of said supply solution and supplying said oxidized solution to a second vessel in which there is disposed a second redox electrode and a second reference electrode so that both of said second electrodes are in contact with said oxidized solution;

determining the electrical potential difference, V₂, between said second electrodes; and

determining the difference between V₁ and V₂.

2. The method of claim 1 in which said supplying step is performed continuously along with continuous removal of said solution from said vessel.

3. The method of claim 1 in which said redox electrode comprises platinum.

4. The method of claim 1 in which said redox electrode comprises gold.

5. The method of claim 1 in which said reference electrode comprises mercury and mercury sulphate.

6. The method of claim 1 in which an additive is provided in at least one of said vessels to provide a stable potential difference, said additive comprising material selected from the group consisting of potassium ferricyanide and potassium iron EDTA.

7. A method to monitor the ratio of sulphite ion species to sulphate ion species in a solution containing said species, said method comprising the steps of:

supplying a solution containing said sulphite and said sulphate ion species to a first portion of a vessel internally divided by a semi-permeable barrier into first and second vessel portions, said first vessel portion having disposed therein a first reference or redox electrode in contact with said solution in said first vessel portion, said second vessel portion having disposed therein a second reference or redox electrode, each of said vessel portions having contained therein the same kind of electrode;

oxidizing a portion of said solution prior to supplying said solution to said second vessel portion;

simultaneously with said previous supply step, supplying to said second vessel portion a quantity of said oxidized solution, said oxidized solution being in contact with said second reference electrode in said second vessel portion; and

determining the electrical potential difference, V, between said first and second electrodes.

8. The method of claim 7 in which said supplying step is performed continuously along with continuous removal of solution from the first and second portions of said vessel.

9. The method of claim 7 in which said barrier comprises an ion exhange membrane.

10. The method of claim 7 in which said barrier comprises a liquid junction.

11. The method of claim 7 in which an additive is provided in at least one of said vessel portions to provide a stable potential difference, said additive comprising material selected from the group consisting of potassium ferricyanide and potassium iron EDTA.