Electrolytic Production of Sodium Perchlorate Using Lead Dioxide Anodes

Abstract

Lead dioxide was investigated as an anode substitute for platinum in the production of sodium perchlorate. Rod shaped deposits were prepared on nickel and platinum clad tantalum wires. The plate was dense, heavy, metallic‐like in appearance and not too fragile for ordinary handling. The first phase of experimentation was performed in small laboratory cells to determine approximate electrolyses data. Larger bench‐scale production cells were also run simulating plant operating conditions. Lead dioxide anodes produce sodium perchlorate at high cumulative current efficiencies. One lead dioxide anode was used in cell operation for 3,000 hr. Cumulative current efficiency for a given anodic current density is a function of the cathode material, cathodic current density, and the additive used. Perchlorate can be produced using nickel, copper, stainless steel, and carbon steel cathodes. Energy requirements, under identical experimental conditions, indicate that stainless steel and nickel are the best cathode materials. A current efficiency of 91.5% was obtained with a stainless cathode at anodic and cathodic current densities of 15.5 amp/dm2 and of 7.25 amp/dm2, respectively. No unusual metallic contamination could be detected in the ammonium perchlorate prepared from the sodium perchlorate.

Electrodeposited lead dioxide coatings

“…Over the past 50 years, perchlorates have been manufactured by the anodic oxidation of the corresponding chlorate and plants in the USA, Japan, Europe and India have used PbO 2 coated graphite or titanium anodes; 8,12,[62][63][64][65][66][67][68][69][70][162][163][164] the most detailed discussion of process conditions come from the Indian group led by Udupa. [62][63][64][65][66][67] Typical conditions are an electrolyte consisting of 250 g litre À1 of the chlorate, pH 7, at a temperature of B330 K, a PbO 2 anode and a steel cathode and a current density of 50 mA cm À2 .…”

Chlorine Oxides and Chlorine Oxygen Acids

“…Platinum is either used in foils or cladded onto rods of some other metal, such as tantalum or copper. Lead dioxide anodes are also used [256]; they consist of a lead dioxide deposit plated on some conductive substrate, such as graphite rods or plates [257][258][259][260]. They are less expensive than platinum, which more than offsets their lower current efficiency (85 %).…”

Preparation and Applications of Graphite Substrate Lead Dioxide (GSLD) Anode

“…Though electrolysis of almost all soluble salts of lead (5,(7)(8)(9)(10) gives lead dioxide deposit under suitable conditions on the anode, the lead nitrate bath is preferred since it may be readily controlled over long plating periods and also due to the high quality of deposit obtained from the bath over a wide range of operating conditions. (19) reported the formation of lead dioxide from the nitrate bath on tantalum or platinum-clad tantalum. Japanese workers (11)(12)(13)(14)(15)(16) used this nitrate bath extensively for depositing lead dioxide on nickel or mild steel substrate.…”