The Dow Chemical Company

Battelle Memorial Institute

Jacques Mosetti

Augusto Porta

Denis Doniat

Jean-Michel Corajoud

A process for removing chlorate from a caustic solution by the reduction of the chlorate with metallic iron. The process is particularly distinguished by the steps of contacting the caustic solution with iron to reduce the chlorate to chloride, contacting the caustic solution containing dissolved iron therein with a conductive substrate to electrolytically precipitate the iron on the substrate, thus providing a caustic solution which is substantially free from iron and chlorate ions, separating the purified portion of the caustic solution, and periodically using the iron coated substrate for treating an untreated portion of the caustic solution to reduce the chlorate to chloride, and periodically reusing the iron depleted substrate, for recovering dissolved iron from the caustic solution. The process of this invention decreases the chlorate content of caustic solutions to an acceptable level of a few ppm and also recovers dissolved iron on an iron depleted substrate for reuse and further reduction of chlorate of an untreated portion of the caustic solution.

Method for removing chlorate from caustic solutions with electrolytic

Process for regenerating activated carbon particles contaminated by oxidizable impurities. An electrolysis cell is divided by a liquid-permeable membrane to define an anodic chamber and a cathode chamber therein both filled in operation with an electrolyte. Recycling conduits communicate with the anode chamber and a recirculating pump to establish a fluid circuit therewith. A suspension of particles of activated carbon contaminated by oxidizable impurities suspended in an aqueous solution of an electrolyte is loaded into the fluid circuit and circulated therethrough. A voltage applied to the electrodes of the electrolysis cell develops an electrolysis reaction in the aqueous solution of the electrolyte and atomic oxygen is liberated at the surface of the anode electrode. As particles of the activated carbon flow through the anode cell they contact the anode electrode and atomic oxygen is liberated at their surfaces which oxidizes impurities adsorbed by the particles. After the carbon particles have been circulated for a sufficient time to oxidize all of the impurities thereon, the regenerated particles of activated carbon and the aqueous solution of the electrolyte are discharged from the recirculating circuit.

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Grand-Lancy, Geneva, Switzerland

Jacques Mosetti