Electrochemical Methods and Products

Abstract

The use, in corrosion protection systems, dewatering systems, and systems to reduce biofouling, of an anode which comprises a conductive polymer composition comprising a polymer and, mixed with the polymer, a conductive filler which comprises an exfoliated graphite.

1 . A system in which a chemical reaction takes place at the surface of an anode, the system being selected from the group consisting of corrosion protection systems, dewatering systems and systems to reduce biofouling, and the system making use of an anode which comprises a conductive polymer composition comprising a polymer and, mixed with the polymer, a conductive filler which comprises an exfoliated graphite. 
     
     
         2 . A system according to  claim 1  wherein the corrosion of a metallic substrate is inhibited by establishing a potential difference between a metallic substrate as a cathode and said anode. 
     
     
         3 . A system according to  claim 2  wherein the metallic substrate and the anode are in contact with soil, and the anode comprises
 (a) a conductor which has a length dimension, a second dimension which is at right angles to the length, and a third dimension which is at right angles to the length and to the second dimension, the length dimension being (i) least 1 m, (ii) at least 20 times the second dimension, and (iii) at least 20 times the third dimension, and 
 (b) a coating which completely surrounds the conductor except at spaced apart connection points, at least part of the coating being in contact with the conductor and being composed of said conductive polymer composition and any other part of the coating being composed of an insulating polymer. 
 
     
     
         4 . A system according to  claim 2  wherein the metallic substrate and the anode are in contact with soil, and the anode is a point anode. 
     
     
         5 . A system according to  claim 2  wherein the metallic substrate is hollow, and the anode
 (a) comprises a conductor which has a length dimension, a second dimension which is at right angles to the length, and a third dimension which is at right angles to the length and to the second dimension, the length dimension being (i) least 1 m, (ii) at least 20 times the second dimension and (iii) at least 20 times the third dimension, and 
 (b) lies within the hollow substrate, and 
 (c) comprises a coating which completely surrounds the conductor except at spaced apart connection points, at least part of the coating being in contact with the conductor and being composed of said conductive polymer composition and any other part of the coating being composed of an insulating polymer. 
 
     
     
         6 . A system according to  claim 2  wherein the metallic substrate is in the form of a sheet which is covered by an insulating material except at spaced-apart connection points, and wherein the anode is in the form of a sheet which is in contact with the metallic substrate at the spaced-apart connection points. 
     
     
         7 . A system according to  claim 1  wherein the water is removed from a water-containing material which lies between the metallic substrate and the anode. 
     
     
         8 . A system according to  claim 1  wherein the current density at the surface of the anode is at least 0.05 mA/cm 2 . 
     
     
         9 . A system according to  claim 1  wherein the conductive polymer composition, when it is subjected to a test which makes use of an electrochemical cell which (i) consists essentially of (a) an anode having the composition as its exterior surface, (b) a graphite cathode, (c) a saturated calomel electrode (SCE), and (d) an electrolyte of 3% salt water, the anode, the cathode, and the calomel electrode being located at the corners of an equilateral triangle having a side of about 1 inch (25 mm) and (ii) the anode is operated at a voltage of 1.55 volts versus the SCE, has a current density of at least 2 mA/cm 2 . 
     
     
         10 . A system according to  claim 1  wherein the exfoliated graphite has a surface area of 15-100 m 2 /g. 
     
     
         11 . A system according to  claim 1  wherein the exfoliated graphite has a surface area of 500-2000 m 2 /g 
     
     
         12 . A system according to  claim 1  wherein the conductive polymer composition contains, in addition to the exfoliated graphite, a particulate conductive filler selected from the group consisting of conductive carbon blacks, acetylene black and graphite. 
     
     
         13 . A system according to  claim 1  wherein the particulate conductive filler is dispersed in a thermoplastic polymer. 
     
     
         14 . A system according to  claim 1  wherein the particulate conductive filler is mixed with a sintered polymer. 
     
     
         15 . An article which is useful as an anode and which comprises
 (a) a conductor which has a length dimension, a second dimension which is at right angles to the length, and a third dimension which is at right angles to the length and to the second dimension, the length dimension being (i) least 1 m, (ii) at least 20 times the second dimension and (iii) at least 20 times the third dimension, and   (b) a coating which completely surrounds the conductor except at spaced apart connection points, at least part of the coating being in contact with the conductor and being composed of a conductive polymer composition which comprises a polymer and, mixed with the polymer, exfoliated graphite, and any other part of the coating being composed of an insulating polymer.   
     
     
         16 - 17 . (canceled) 
     
     
         18 . A system in which corrosion of a metallic substrate is inhibited by establishing a potential difference between a metallic substrate as a cathode and an anode which comprises a conductive polymer composition comprising a polymer and, mixed with the polymer, a conductive filler which comprises an exfoliated graphite. 
     
     
         19 . A system according to  claim 18  wherein the metallic substrate and the anode are in contact with soil, and the anode comprises
 (a) a conductor which has a length dimension, a second dimension which is at right angles to the length, and a third dimension which is at right angles to the length and to the second dimension, the length dimension being (i) least 1 m, (ii) at least 20 times the second dimension and (iii) at least 20 times the third dimension, and 
 (b) a coating which completely surrounds the conductor except at spaced apart connection points, at least part of the coating being in contact with the conductor and being composed of said conductive polymer composition, and any other part of the coating being composed of an insulating polymer. 
 
     
     
         20 . A system according to  claim 18  wherein the metallic substrate and the anode are in contact with soil, and the anode is a point anode. 
     
     
         21 . A system according to  claim 18  wherein the metallic substrate is hollow, and the anode
 (a) comprises a conductor which has a length dimension, a second dimension which is at right angles to the length, and a third dimension which is at right angles to the length and to the second dimension, the length dimension being (i) least 1 m, (ii) at least 20 times the second dimension, and (iii) at least 20 times the third dimension, 
 (b) lies within the hollow substrate, and 
 (c) a coating which completely surrounds the conductor except at spaced apart connection points, at least part of the coating being in contact with the conductor and being composed of said conductive polymer composition, and any other part of the coating being composed of an insulating polymer. 
 
     
     
         22 . A system according to  claim 18  wherein the metallic substrate is in the form of a sheet which is covered by an insulating material except at spaced-apart connection points, and wherein the anode is in the form of a sheet which is in contact with the metallic substrate at the spaced-apart connection points.