Alliedsignal Inc.

Somanahalli N Subbanna

Charles L Redmon

Robert A Smith

Christian A Wamser

Barry J Boghean

Douglas G Frick

The present invention provides a process for recovering arsenic acid from a starting mixture comprising sulfuric and arsenic acids and water. In step (a), the starting mixture is treated with a sulfur (IV) compound which will reduce the arsenic acid to arsenic (III) compound under conditions sufficient to substantially convert the arsenic acid to arsenic (III) wherein the resulting mixture comprises arsenic (III) compound, the sulfur (IV) compound, sulfuric acid, and water. In step (b), the resulting mixture is purged with gas to substantially remove the sulfur (IV) compound from the mixture wherein the purged mixture comprises the arsenic (III) compounds, sulfuric acid, and water. In step (c), the purged mixture is treated under conditions sufficient to substantially separate the arsenic (III) compounds from the purged mixture. In step (d), the separated arsenic (III) compound is reacted with an oxidizing agent to substantially convert arsenic (III) compound to arsenic acid wherein the final mixture comprises arsenic acid, unreacted oxidizing agent, and water. In step (e), impurities are removed from the final mixture to provide substantially pure aqueous arsenic acid.

Process for separating arsenic acid from an aqueous mixture comprising

The present invention provides a process for the conversion of hazardous hexafluoroarsenic acid or any salt thereof to arsenic acid or salt thereof which can be rendered nonhazardous. In particular, the hexafluoroarsenic acid or salt is converted to arsenic acid or salt which can be converted to a water insoluble salt. Known insolubilization and stabilization technology then renders the material nonhazardous. The present process involves converting hexafluoroarsenic acid or salt thereof contained in an aqueous mixture to arsenic acid or salt thereof. The process comprises the steps of: (a) adding acid selected from the group consisting of sulfuric acid, arsenic acid, perchloric acid, and mixtures thereof to the aqueous mixture in an amount sufficient to catalyze the hydrolysis of the hexafluoroarsenic acid or salt thereof and raising the temperature of the aqueous mixture before, during, or after the acid addition sufficient to remove substantially all of the hydrogen fluoride in subsequent step (b); (b) passing an inert gas through the heated acid mixture steam in a quantity sufficient to remove substantially all of the hydrogen fluoride in the heated acid mixture from the heated acid mixture; and (c) separating substantially all of the hydrogen fluoride from the heated acid mixture whereupon the hexafluoroarsenic acid or salt thereof converts substantially to arsenic acid or salt thereof.

Process for converting hexafluoroarsenic acid or any salt thereof to

A process for manufacturing high purity anhydrous hydrogen fluoride (HF) having low levels of arsenic impurity by contacting anhydrous hydrogen fluoride product, or an intermediate product obtained during the manufacture of HF, with hydrogen peroxide to oxidize the arsenic impurity in the presence of a catalyst which comprises a catalytic amount of a component selected from the group consisting of molybdenum, a molybdenum compound, vanadium, and a vanadium compound, and a phosphate compound. The volatile trivalent arsenic impurity in the anhydrous hydrogen fluoride is oxidized to a non-volatile pentavalent arsenic compound and the resultant mixture is distilled to recover high purity anhydrous hydrogen fluoride with reduced levels of arsenic impurity. In one embodiment, an oxidizing agent such as nitric acid or a nitrate salt is added to the reaction mixture to oxidize organic compounds.

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East Amherst, NY, United States of America

Somanahalli N Subbanna