Occidental Chemical Corporation

Oxytech Systems, Inc.

Hooker Chemicals & Plastics Corporation

Ursula I Keller

Robert L Zeller

Russell J Morgan

Arthur C Schulz

Robert Kiszewski

Edward H Cook, Jr

Tilak V Bommaraju

Christine A Lazarz

Disclosed is a method of removing soluble vanadium from an aqueous stream containing sodium chromate or sodium bichromate. The liquor is passed over a water-insoluble trivalent chromium compound, and the vanadium in the liquor is extracted from the liquor onto the trivalent chromium compound. The process is especially useful in removing vanadium from a recycled concentrated sodium bichromate liquor to prevent the buildup of vanadium therein.

Vanadium removal in aqueous streams

Disclosed is a method of making chromic acid by electrolyzing an aqueous solution of sodium bichromate until the sodium bichromate is converted to chromic acid at a bichromate percent conversion of about 1 to about 48.4. Sulfuric Acid is then added to the aqueous solution in an amount between stoichiometric and about 30 wt % in excess of stoichiometric to convert the remaining sodium bichromate to chromic acid. This results in the precipitation of chromic acid, which is separated from the aqueous solution.

Efficient electrolytic method of making chromic acid from sodium

An improved diaphragm for an electrolytic cell is prepared by mixing a slurry of an additive, such as poly(ethylene chlorotrifluoroethylene), and asbestos fibers with a dispersion of titanium dioxide in isopropyl alcohol, depositing the treated asbestos fibers onto a cathode, heating the diaphragm to an elevated temperature of from about 100.degree. C. to about 400.degree. C., and allowing the diaphragm to cool. The diaphragm prepared according to this process exhibits improved mechanical strength and integrity as well as a decrease in electrical energy consumption in comparison to diaphragms prepared using conventional techniques.

Diaphragm for an electrolytic cell

An improved diaphragm for an electrolytic cell is prepared by mixing a slurry of asbestos fibers with a dispersion of titanium dioxide in isopropyl alcohol, depositing the treated asbestos fibers onto a cathode, heating the diaphragm to an elevated temperature of from about 100.degree. C. to about 300.degree. C., and allowing the diaphragm to cool. The diaphragm prepared according to this process exhibits improved mechanical strength and integrity as well as a decrease in electrical energy consumption in comparison to diaphragms prepared using conventional techniques.

Hydrophobic polymeric separators are made wettable to electrolytic cell fluids by a post-manufacturing process of treating with fluorinated surface-active agents. The application of a hydrophilic film of fluorosurfactant onto separator surfaces followed by drying renders the separator permanently wettable. The hydrophilic surfaces rendered inert by drying are reactivated in-situ after installation of the separator by contacting the separator surfaces with heated aqueous solution. The pre-installation process provides a convenient means for shipping fully manufactured separators and for their storage by users until actually needed. From an operational standpoint, the pre-installation process eliminates fouling of the cell with foam occurring with conventional in-situ wetting procedures.

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Queenston, Canada

Ursula I Keller