Abstract: A process for converting in a single pass an aqueous alkaline pH, alkali metal chlorite solution into an aqueous chlorine dioxide-containing solution that involves the combination of (1) using an electrochemical acidification cell to lower the pH value of the aqueous alkali metal chlorite feed before it enters the anode compartment of an electrochemical oxidation cell where the chlorite is converted to chlorine dioxide with (2) using an anolyte flow pattern where the anolyte passes through a porous, high surface area electrode. This process results in a substantially improved conversion efficiency per pass.
Type:
Grant
Filed:
October 16, 1998
Date of Patent:
March 20, 2001
Assignee:
Sterling Pulp Chemicals, Ltd.
Inventors:
Marek Lipsztajn, Gerald Cowley, Jerry J. Kaczur
Abstract: Chlorine dioxide is generated by electrochemical oxidation of sodium chlorite in an anode compartment of a cation-exchange membrane-divided cell in the presence of significant quantities of sodium chlorate and is recovered in a suitable recipient medium by passing the chlorine dioxide through a hydrophobic microporous membrane. Water balance in a continuous operation is maintained by removing water from the anolyte by transporting the same partly across the hydrophobic microporous membrane in vapor form and partly across the cation-exchange membrane.
Type:
Grant
Filed:
October 28, 1997
Date of Patent:
October 12, 1999
Assignee:
Sterling Pulp Chemicals, Ltd.
Inventors:
Gerald Cowley, Marek Lipsztajn, George Joseph Ranger, Ron K. Schaible, Ty V. Tran, Darren F. Lawless
Abstract: Chlorine dioxide is generated by electrochemical oxidation of sodium chlorite in an anode compartment of a cation-exchange membrane-divided cell and is recovered in a suitable recipient medium by passing the chlorine dioxide through a hydrophobic microporous membrane. Water balance in a continuous operation is maintained by removing water from the anolyte by transporting the same partly across the hydrophobic microporous membrane in vapor form and partly across the cation-exchange membrane.
Type:
Grant
Filed:
March 13, 1996
Date of Patent:
August 3, 1999
Assignee:
Sterling Pulp Chemicals, Ltd.
Inventors:
Gerald Cowley, Marek Lipsztajn, George Joseph Ranger
Abstract: Control of sulfate and perchlorate impurity levels is provided in a procedure for manufacturing crystalline sodium chlorate by electrolyzing an aqueous solution of sodium chloride and crystallizing sodium chlorate from the resulting aqueous solution of sodium chlorate and sodium chloride. The mother liquor from the crystallization, or a portion thereof, is treated simultaneously with calcium chloride to remove sulfate ions by precipitating calcium sulfate and with potassium chloride to remove perchlorate ions by precipitating potassium perchlorate.
Abstract: A salt solution, particularly aqueous sodium chlorate, is acidified electrolytically at a higher current efficiency than has previously been the case by employing a plurality of multiple compartment cells, in which the effluent from intermediate compartments is passed through more anodic compartments.
Type:
Grant
Filed:
May 12, 1993
Date of Patent:
January 2, 1996
Assignee:
Sterling Pulp Chemicals, Ltd.
Inventors:
Marek Lipsztajn, Gerald Cowley, Dana Gourley