Abstract: A Ag/AgCl electrode includes a rigid tube within which a Ag/AgCl conductor is mounted by epoxy. An insulated wire lead is coupled by a solder joint to the Ag/AgCl conductor. An optional plastic cap seals the upper end of the tube and the wire lead extends out of the upper end of the tube and through the plastic cap. A sodium chloride solution is provided in the lower end of the tube such that the conductor is bathed in the solution. The solution is maintained within the tube by a porous glass, ceramic, or polymeric plug which is press fit into the lower end of the tube. The lower end of the tube, including the plug, is coated with a water soluble non-toxic substance. The water soluble coating is preferably made from a concentrated solution of polyvinyl alcohol (PVA) in deionized or RO water which is preferably applied by dip coating and air drying.

Abstract: An apparatus for reducing nitrates in an aqueous solution includes an electrochemical cell having a container for containing the aqueous solution containing nitrates, a carbon fiber cathodic electrode, a carbon fiber anodic electrode, and a reference electrode immersed in the aqueous solution, and an electronic control circuit which impresses a voltage across the electrodes causing electrochemical reduction/oxidation reactions on the surfaces of the electrodes. The electrodes are at a potential such that nitrates are reduced to gaseous products, and further such that hydrogen, oxygen, chlorine, an other noxious substances are not produced. The cell may be a flow cell or a holding tank and apparatus of different size and capacity are disclosed. The apparatus is useful in reducing nitrates in any water system and is particularly useful in reducing nitrates in aquatic systems without harming aquatic life.