Abstract: Planar electrodes include a carbon fiber cloth which is woven or braided from a plurality of PAN-derived carbon fibers and which is mounted in a frame. The frame is preferably made of an inert plastic material such as TEFLON, PVC, or DELRIN and the carbon fiber cloth is preferably affixed to the frame with metal strips and fasteners. The metal strips are preferably titanium or a noble metal and the fasteners are preferably made of the same metal as the strips. The metal strips form a low impedance electrical contact with the carbon fiber cloth and enable the electrode to be coupled to a wire lead or electrical contact for use in an electrochemical circuit. According to a second embodiment, the carbon fiber cloth is sandwiched between two metal frames. According to a third embodiment, the carbon fiber cloth is sandwiched between two plastic frames with conductive foil strips or titanium strips forming an electrical contact with the carbon fiber cloth.

Abstract: A carbon fiber electrode is coated with a noble metal oxide to create a noble metal oxide electrode with a very large surface area. According to a presently preferred embodiment, the noble metal oxide is iridium oxide. A method of making the electrode includes preparing a solution of iridium chloride and isopropyl alcohol, dipping a carbon fiber electrode into the solution, drying the electrode in the presence of nitrogen and heat, and heat treating the electrode in the presence of oxygen. An apparatus for removing nitrates from water includes an electrochemical flow cell through which the aqueous solution containing nitrates flows or a holding tank cell into which the solution is introduced and then released after processing, and an electrode system including an anodic iridium oxide coated carbon fiber electrode as described above, a carbon fiber cathodic electrode and a reference electrode.