# US 7,407,642 B2 · Chlorine dioxide generation method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,407,642 B2 - Document ID: US7407642B2 - Status: Granted - Kind: B2 - Application number: 11/372,464 - Filed: 2006-03-10 - Published: 2007-09-13 - Granted: 2008-08-05 - Earliest claimed: 2006-03-10 - Assignees: Bio-Chem Resources - Inventors: Frederick P. Mussari; David Francis; Wilfried Schmitz - Web page: https://patentgrep.com/patent/US7407642B2 ## CPC - C01B 11/024: {from chlorites} - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} ## Abstract A method generating chlorine dioxide is provided. The method uses sodium chlorite solution and diluted sulfuric acid to generate chlorine dioxide with a significantly higher rate of conversion of chlorite to chorine dioxide than has been previously reported with sulfuric acid/chlorite chlorine dioxide generation. ## Claims ### Claim 1 A two chemical conversion method for preparing chlorine dioxide, comprising: reacting a 7.5-25 weight % aqueous sodium chlorite solution with a 20-50 weight % aqueous sulfuric acid as sole constituents in a reaction chamber sized to allow the aqueous sodium chlorite solution and the aqueous sulfuric acid to react for about 5 seconds to about 300 seconds to form a reaction mixture comprising chlorine dioxide in which 75% or more and 85% or less of chlorite ion in the sodium chlorite solution is converted to chlorine dioxide. ### Claim 2 (depends on 1) The method of claim 1, further comprising: diluting a concentrated sulfuric acid with water to 20% to 50% by weight and cooling the diluted aqueous sulfuric acid to remove heat of reaction and using the cooled 20 to 50% by weight aqueous sulfuric acid in the reacting step. ### Claim 3 (depends on 1) The method of claim 1, wherein the aqueous sodium chlorite solution and the aqueous sulfuric acid are contacted for about 30 seconds to about 60 seconds. ### Claim 4 (depends on 1) The method of claim 1, wherein a prolonged time of storage of the reaction mixture prior to diluting the reaction mixture with water does not result in a significant loss of the produced chlorine dioxide by reaction with water to form chlorate. ### Claim 5 A method for generating chlorine dioxide, comprising: introducing an aqueous sodium chlorite solution and an aqueous sulfuric acid separately into a reactor as sole constituents, and reacting the aqueous sodium chlorite with the aqueous sulfuric acid to form a reaction mixture by converting 75% or more and 85% or less of chlorite ions to chlorine dioxide, wherein the aqueous sodium chlorite solution has a concentration in the range of 7.5-25% by weight, and the aqueous sulfuric acid has a concentration in the range of 20-50% by weight. ### Claim 6 (depends on 5) The method of claim 5, further comprising storing the reaction mixture in the reactor for about 1 to 15 minutes without a significant conversion of the chlorine dioxide to chlorate. ### Claim 7 (depends on 5) The method of claim 5, wherein the reaction mixture is substantially chlorine and chlorite free. ### Claim 8 (depends on 5) The method of claim 5, wherein the reactor has a discharge opening which communicates with a treatment stream, and the reaction mixture is not diluted until the reaction is complete. ### Claim 9 (depends on 5) The method of claim 5, further comprising: diluting a concentrated sulfuric acid to 20% to 50% by weight with water and cooling the diluted aqueous sulfuric acid to remove heat of reaction and using the cooled 20 to 50% by weight aqueous sulfuric acid in the reacting step. ### Claim 10 (depends on 1) The method of claim 1, further comprising discharging the reaction mixture from the reactor via a discharge opening of the reactor to a treatment stream. ### Claim 11 (depends on 2) The method of claim 2, wherein the concentrated sulfuric acid is diluted with water to approximately 50% by weight and cooled. ### Claim 12 (depends on 1) The method of claim 1, wherein the aqueous sulfuric acid has a concentration of approximately 50% by weight. ### Claim 13 (depends on 1) The method of claim 1, wherein the percent conversion of chlorite ion to chlorine dioxide is determined by four step iodometric titration. ### Claim 14 A method for preparing chlorine dioxide, comprising: reacting a 7.5-25 weight % aqueous sodium chlorite solution with a 20-50 weight % aqueous sulfuric acid solution as sole constituents in a reactor for 5 to 300 seconds to obtain a reaction mixture in which 81.5% or more and 85% or less of chlorite ion in the aqueous sodium chlorite solution is converted to chlorine dioxide. ### Claim 15 The method of 14, further comprising: diluting a concentrated sulfuric acid to approximately 50% by weight aqueous sulfuric acid solution and cooling the aqueous sulfuric acid solution and using the resulting cooled, diluted sulfuric acid in the reacting step. ### Claim 16 The method of 14, further comprising storing the reaction mixture in the reactor for about 1 to 15 minutes without a significant conversion of the chlorine dioxide to chlorate. ### Claim 17 The method of 14, further comprising discharging the reaction mixture to a treatment stream via a discharge opening of the reactor. ### Claim 18 (depends on 14) The method of claim 14, wherein at least 84% of the chlorite ion is converted to the chlorine dioxide in the reaction mixture. ### Claim 19 (depends on 15) The method of claim 15, further comprising discharging the reaction mixture from the reactor via a discharge opening of the reactor to a treatment stream.