Chemically modified electrodes and method of using same in removing metals from a fluid

• US 5,421,967 A
• Filed: 10/25/1993
• Issued: 06/06/1995
• Est. Priority Date: 10/25/1993
• Status: Expired due to Fees

• Current Assignee: Nalco Chemical Company (Ecolab, Inc.)
• Original Assignee: Nalco Chemical Company (Ecolab, Inc.)
• Inventors: Tubergen, Karen R.
• Primary Examiner(s): Niebling, John
• Assistant Examiner(s): Phasge, Arun S.
• Application Number:
  US08/142,605
• Time in Patent Office: 589 Days
• Field of Search: 204/141.5, 204/149, 204/229, 204/231, 204/294, 204/275
• US Class Current: 210/709
• CPC Class Codes: C02F 1/5209 Regulation methods for flocculation or precipitation
• CPC Class Codes: G05D 21/02 characterised by the use of electric means

Abstract

A chemically modified electrode is provided for selectively and sensitively detecting the presence of precipitant within wastewater. A system and a method, utilizing the chemically modified electrode, are provided to monitor and control feed of a precipitant to a reservoir containing a fluid, such as wastewater, with metals therein. The chemically modified electrode in conjunction with a reference electrode are provided in the reservoir for measuring current flowing therebetween. In response, the feed of the precipitant may be controlled to maintain the current within a predetermined range.

Claims

1. A system for removing metals from a fluid comprising:

a reservoir for receiving the fluid therein;

a precipitant feed unit for feeding a precipitant into the reservoir;

a carbon paste electrode modified with an effective amount of iodine to allow the iodine to act as a catalytic modifier and a reference electrode disposed in the reservoir for measuring a current therebetween; and

a controller responsive to the measured electrochemical potential for automatically controlling feed rate of the precipitant to the reservoirs.

2. The system of claim 1 wherein the controller feeds the precipitant to maintain the current within a desired range.

3. The system of claim 1 wherein the reservoir is a wastewater reservoir.

4. The system of claim 1 wherein the precipitant feed unit is a dialkyldithiocarbamate precipitant feed unit.

5. The system of claim 1 wherein the amount of iodine present in the chemically modified electrode ranges from about 0.5 to 2.0 wt. %.

6. The system of claim 1 further including a counter electrode to minimize the current flowing through the reference electrode.

7. A method for removing metals from a fluid comprising the steps of:

providing the fluid from a source to a reservoir;

providing a chemically modified electrode and a reference electrode in the reservoir for measuring a current therebetween; and

feeding a dialkyldithiocarbamate into the reservoir.

8. The method of claim 7 wherein the fluid is wastewater.

9. The method of claim 7 further comprising the step of:

controlling feed rate of the precipitant into the reservoir.

10. The method of claim 9 wherein the feed rate is controlled to maintain the current within a desired range.

11. The method of claim 7 further including the step of providing a counter electrode to facilitate the measuring of the current.

12. The method of claim 7 wherein the chemically modified electrode is a carbon paste electrode modified with an effective amount of iodine to allow the iodine to act as a catalytic modifier.

13. A method for removing metals from a fluid comprising the steps of:

providing the fluid from a source to a reservoir;

providing a carbon paste electrode modified with an effective amount of iodine to allow the iodine to act as a catalytic modifier and a reference electrode in the reservoir for measuring a current therebetween; and

feeding a precipitant into the reservoir.

14. The method of claim 13 wherein the fluid is wastewater.

15. The method of claim 13 wherein the precipitant is a dialkyldithiocarbamate.

16. The method of claim 13 further comprising the step of:

controlling feed rate of the precipitant into the reservoir.

17. The method of claim 16 wherein the feed rate is controlled to maintain the current within a desired range.

18. The method of claim 13 further including the step of providing a counter electrode to facilitate the measuring of the current.