Chloramine amperometric sensor

• US 20030205465A1
• Filed: 05/03/2002
• Published: 11/06/2003
• Est. Priority Date: 05/03/2002
• Status: Active Grant

• Current Assignee: Rosemount Analytical, Inc. (Emerson Electric Company)
• Original Assignee: Rosemount Analytical, Inc. (Emerson Electric Company)
• Inventors: Feng, Chang-Dong
• Granted Patent: US 7,087,150 B2
• Time in Patent Office: Days
• US Class Current: 204/415
• CPC Class Codes: G01N 2033/184 herbicides, pesticides, fungicides, insecticides, or the like
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 33/0049 for halogenated organic compounds

Abstract

A chloramine amperometric sensor includes a sensor body with an electrolyte disposed inside the sensor body. A membrane is coupled to the sensor body and adapted to pass chloramine therethrough. A reference electrode is disposed in the electrolyte and coupled to a first conductor. A second conductor is coupled to a working electrode that is disposed proximate the membrane. The working electrode is constructed from a noble metal in non-compact form. The non-compact form can be a Gas Diffusion Electrode, which can include metal mesh, carbon paper, carbon cloth, metal/carbon powder loaded on a porous membrane or any combination thereof.

Claims

1. An amperometric sensor for measuring chloramine, the sensor comprising:

a sensor body;

an electrolyte disposed within the sensor body;

a membrane coupled to the sensor body and adapted to pass chloramine therethrough into the sensor body;

a reference electrode disposed in the electrolyte;

a first conductor coupled to the reference electrode;

a working electrode disposed proximate the membrane, the working electrode being constructed from a noble metal in non-compact form; and

a second conductor coupled to the working electrode.

2. The sensor of claim 1, wherein the non-compact form is a Gas Diffusion Electrode.

3. The sensor of claim 2, wherein the Gas Diffusion Electrode is loaded with the noble metal in a powdered form.

4. The sensor of claim 3, wherein the noble metal is platinum.

5. The sensor of claim 4, wherein the platinum is loaded onto the Gas Diffusion Electrode at approximately 80% Pt/C.

6. The sensor of claim 2, wherein the Gas Diffusion Electrode includes a carbon cloth.

7. The sensor of claim 1, wherein the non-compact form of the working electrode is a mesh.

8. The sensor of claim 7, wherein the working electrode is constructed from gold mesh.

9. The sensor of claim 1, wherein the pH of the electrolyte is within the range of about 9.0 to about 11.0.

10. The sensor of claim 1, wherein the sensor has an output that is linear in concentrations of chloramine ranging from about 0 ppm to about 8.0 ppm.

11. The sensor of claim 1, wherein the reference electrode is constructed from silver.

12. The sensor of claim 1, wherein the electrolyte includes potassium chloride.

13. The sensor of claim 12, wherein the potassium chloride is present at a concentration of about 0.1 M.

14. In a chemical sensor, a method of measuring chloramine, the method comprising:

placing a testing solution containing chloramine in fluidic communication with a membrane permeable to chloramine;

providing a working electrode having a noble metal in non-compact form, wherein the working electrode is permeated with electrolyte;

diffusing the chloramine through the membrane into the working electrode; and

measuring a current between the working electrode and a reference electrode disposed in the electrolyte.

15. A system for monitoring chloramine concentration, the system comprising:

a chloramine amperometric sensor including;

a sensor body;

an electrolyte disposed within the sensor body;

a membrane coupled to the sensor body and adapted to pass chloramine therethrough into the sensor body;

a reference electrode disposed in the electrolyte;

a working electrode disposed proximate the membrane, the working electrode being constructed from a noble metal in non-compact form; and

an analysis device coupled to the reference electrode and the working electrode, the analysis device adapted to provide a sufficient working potential and to measure a current flowing between the reference electrode and working electrode and provide an indication of chloramine concentration based on the current.

16. The system of claim 15, wherein the analysis device is a transmitter.