Elf Atochem North America, Inc.

Pennwalt Corporation

Jeffrey H Yen

Glenn T Carroll

John A Wismer

Michael J Lindstrom

Roger T Clark

William J Tuszynski

Vijay R Srinivas

Richard C Spung

A process is disclosed wherein arsenic dissolved in wastewater or groundwater is removed from solution by precipitation thereof as calcium arsenate formed by the reaction of the arsenic with lime or hydrated lime in a heated solution at a pH of about 11 to about 13. It is preferred that the arsenic is first converted by oxidation to its pentavalent form.

Hot lime precipitation of arsenic from wastewater or groundwater

In the process of removing heavy metals from aqueous solutions (groundwater) by precipitation of a salt thereof, an oxidizing agent is optionally used to increase the valence of said metal, and a precipitation-enhancing agent is added to maximize particle size of the precipitate and to facilitate its separation from said solution.

Process for removing heavy metals from aqueous solutions

A process is disclosed for the removal of dissolved heavy metals from aqueous solution contaminated therewith wherein at least one of said heavy metals is reacted with a water-soluble inorganic sulfide or hydrosulfide at a defined elevated temperature and a controlled pH of between about 2 to about 3.5 to thereby precipitate heavy metal sulfide, and thereafter separating the precipitate from the filtrate.

Sulfide precipitation of heavy metals from aqueous solutions

A process for removing sulfur from an organic sulfide containing three or more chemically bound sulfur atoms is disclosed wherein said sulfide is contacted with a defined catalyst at elevated temperature to increase the disproportionation rate and the corresponding sulfide of lower sulfur rank is continuously removed from the reaction zone.

Process for removing sulfur from organic sulfides

In the process of removing heavy metals from aqueous solutions by precipitation of a salt thereof at increased pH, multiple stage precipitation by upward stepwise pH adjustment and solid separation at each stage is used to facilitate the manufacture of a product of high purity.

Multiple-stage precipitation process for heavy metals in aqueous solution

A process for removing sulfur from an organic polysulfide by reaction with an aqueous stripping solution of at least one sulfide salt and/or hydrosulfide salt in a multi-stage, continuous, countercurrent flow, reaction system wherein the sulfur is stripped from the polysulfide into the aqueous stripping solution phase which is separated from the polysulfide organic phase.

Process for removing sulfur from organic polysulfides

Sulfur-laden liquid organic phase dimethyl polysulfide (DMPS) is caused to rise from a sour gas well by reaction of the gaseous sulfur component within the well with a sulfur solvent, typically dimethyl disulfide (DMDS). The DMPS is contacted by an extraction or stripping liquid in a vertical column continuous multistage countercurrent flow extractor especially designed to promote high interfacial area contact between the liquids while flowing in opposing directions within the column.

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Woolwich, NJ, United States of America

Jeffrey H Yen