Continuous chlorine dioxide generation

Abstract

The present invention provides a system for continuously and efficiently producing low concentrations of aqueous chlorine dioxide from a dilute continuous feed stream of aqueous chlorite.

1 . A method for producing a continuous aqueous solution of chlorine dioxide comprising the steps of: 
 a obtaining an aqueous alkali metal or alkaline earth metal chlorite solution having up to about 35 wt % of the alkali metal or alkaline earth metal chlorite,    b. with water, diluting the aqueous alkali metal or alkaline earth metal chlorite to form a continuous feed stream having a chlorite concentration of between about 0.001 wt % and about 0.25 wt %,    c. irradiating the continuous feed stream in a reacting vessel with ultraviolet light radiation, and    d. producing a continuous aqueous product stream containing between about 0.0005 wt % and about 0.05 wt % chlorine dioxide.    
     
     
         2 . The method of  claim 1 , wherein the aqueous alkali metal or alkaline earth metal chlorite is sodium chlorite.  
     
     
         3 . The method of  claim 1 , wherein the continuous feed stream is irradiated in a reacting vessel with ultraviolet radiation having primary wavelengths of 254 nm.  
     
     
         4 . The method of  claim 1 , wherein the continuous feed stream reacts in the presence of the ultraviolet radiation to form primarily chlorine dioxide, chloride and chlorate.  
     
     
         5 . The method of  claim 1 , wherein the continuous feed stream contains between about 0.00052 pound of chlorite to about 0.0034 pound of chlorite for each watt·hr of ultraviolet radiation applied.  
     
     
         6 . The method of  claim 1 , wherein the chlorite in the continuous feed stream is converted by 20 wt % to 43 wt % to chlorine dioxide.  
     
     
         7 . The method of  claim 4 , wherein the chlorite in the continuous feed stream reacts preferentially to form chlorine dioxide and chloride in approximately equal molar quantities.  
     
     
         8 . The method of  claim 1 , wherein the product stream has a pH in the alkaline range.  
     
     
         9 . The method of  claim 1 , wherein the product stream has a pH between 9.0 and 9.7.  
     
     
         10 . The method of  claim 1 , wherein the product stream has a pH less than 10.