Method and Apparatus for Electrochemical Bromide Removal

Abstract

The present invention provides apparatuses, systems and methods for the controllable oxidation of bromide into bromine either directly through electrochemical (EC) anodes or indirectly through electrochemically generated oxidants.

What is claimed is: 
     
         1 . An electrogeneration system for the oxidation of bromide to bromine in an aqueous electrolyte solution comprising:
 a treatment chamber comprising at least one electrochemical cell to contain an aqueous electrolyte solution and an inlet and an outlet, wherein the aqueous electrolyte solution comprises bromide ions, chloride ions or a mixture of bromide and chloride ions;   at least one anode in the treatment chamber; and   at least one cathode in the treatment chamber;   a power supply in communication with the at least one anode and the at least one cathode to generate an electric current sufficient to generate bromine, chlorine, chloride ions, or a combination thereof and reduce bromate formation in the aqueous electrolyte solution;   an electrolyte reservoir for holding the aqueous electrolyte solution connected to the inlet;   an aqueous electrolyte solution flow controller to control a selected volume of the electrolyte solution between the electrolyte reservoir and the electrochemical cell; and   a pH adjusting mechanism comprising an acid reservoir for holding an acid connected to the treatment chamber, a pH monitor in communication with the treatment chamber; and a control unit in communication with the pH monitor and the acid reservoir to adjust the pH by adding the acid from the acid reservoir to the aqueous electrolyte solution.   
     
     
         2 . The apparatus of  claim 1 , further comprising a bromine detection device in communication with the aqueous electrolyte solution to monitor the formation of bromine. 
     
     
         3 . The apparatus of  claim 1 , further comprising a separation device to separate the bromine molecules from the aqueous electrolyte solution. 
     
     
         4 . The apparatus of  claim 1 , wherein the at least one anode and the at least one cathode are independently an array or a ribbon mesh. 
     
     
         5 . The apparatus of  claim 1 , wherein the at least one anode comprises a ruthenium oxide composition, a tantalum oxide composition or a ruthenium oxide and a tantalum oxide composition. 
     
     
         6 . The apparatus of  claim 1 , wherein the chloride ions are generated at the at least one anode. 
     
     
         7 . The apparatus of  claim 1 , wherein the chloride ions comprise between 20-80 ppm. 
     
     
         8 . The apparatus of  claim 1 , wherein the bromide ions comprise between 20-100 ppm. 
     
     
         9 . The apparatus of  claim 1 , further comprising between 700-2000 ppm SO 4   −2  and peroxodisulfate is generated at the at least one anode. 
     
     
         10 . The apparatus of  claim 1 , wherein the pH is between 0.5-6.0. 
     
     
         11 . The apparatus of  claim 1 , wherein the current is between 0.01 to 5.0×10 5  A and the voltage is between 0.1 to 1000 V sufficient to generate bromine, chlorine, chloride ions or a combination thereof and reduce bromate formation in the aqueous electrolyte solution. 
     
     
         12 . A method for the oxidation of bromide to bromine in a for-treatment aqueous electrolyte solution by an electrochemical technique comprising the steps of:
 providing a treatment chamber comprising at least one electrochemical cell to contain an aqueous electrolyte solution and an inlet and an outlet, wherein the aqueous electrolyte solution comprises bromide ions, chloride ions or a mixture of bromide and chloride ions; at least one anode in the treatment chamber; and at least one cathode in the treatment chamber;   connecting a power supply to the at least one anode and the at least one cathode to generate an electric current sufficient to generate bromine, chlorine, chloride ions, or a combination thereof and reduce bromate formation in the aqueous electrolyte solution;   providing an electrolyte reservoir for holding the aqueous electrolyte solution connected to the inlet;   adjusting an aqueous electrolyte solution flow controller to flow a selected volume of the electrolyte solution between the electrolyte reservoir and the electrochemical cell;   providing a pH adjusting mechanism comprising an acid reservoir for holding an acid connected to the treatment chamber, a pH monitor in communication with the treatment chamber; and a pH control unit in communication with the pH monitor and the acid reservoir to adjust the pH by adding the acid from the acid reservoir to the aqueous electrolyte solution;   adjusting the pH to between 0.5-6.0 with the pH control unit; and   adjusting the power supply to provide a current between 0.01 to 5.0×10 5  A and the voltage is between 0.1 to 1000 V sufficient to generate bromine, chlorine, chloride ions or a combination thereof and reduce bromate formation in the aqueous electrolyte solution; and   oxidizing bromide to bromine through oxidation at the one or more anodes, oxidizing indirectly bromide to bromine through oxidation through electrochemically generated oxidants or both.   
     
     
         13 . The method of  claim 12 , further comprising the step of determining a bromine concentration. 
     
     
         14 . The method of  claim 12 , further comprising the step of separating the bromine molecules from the aqueous electrolyte solution. 
     
     
         15 . The method of  claim 12 , wherein the at least one anode and the at least one cathode are independently an array or a ribbon mesh. 
     
     
         16 . The method of  claim 12 , wherein the chloride ions are generated at the at least one anode. 
     
     
         17 . The method of  claim 12 , further comprising the step of adjusting the chloride ions to between 20-80 ppm. 
     
     
         18 . The apparatus of  claim 1 , further comprising the step of adjusting a SO 4   −2  concentration to between 700-2000 ppm and generating peroxodisulfate at the at least one anode. 
     
     
         19 . An electrogeneration system for the oxidation of bromide to bromine in an aqueous electrolyte solution comprising:
 a treatment chamber comprising at least one electrochemical cell to contain an aqueous electrolyte solution and an inlet and an outlet, wherein the aqueous electrolyte solution comprises bromide ions, chloride ions or a mixture of bromide and chloride ions;   at least one anode in the treatment chamber; and   at least one cathode in the treatment chamber;   a power supply in communication with the at least one anode and the at least one cathode to generate an electric current sufficient to generate bromine, chlorine, chloride ions or a combination thereof and reduce bromate formation in the aqueous electrolyte solution; and   an aqueous electrolyte solution source connected to the inlet to provide the aqueous electrolyte solution to the treatment chamber.   
     
     
         20 . The system of  claim 19 , wherein the chloride ions are generated at the at least one anode and the chloride ions comprise between 20-80 ppm. 
     
     
         21 . The system of  claim 19 , wherein the aqueous electrolyte solution further comprises between 700-2000 ppm SO 4   −2  and peroxodisulfate is generated at the at least one anode. 
     
     
         22 . The apparatus of  claim 1 , wherein the pH of the aqueous electrolyte solution is between 0.5-6.0.