Methods and Apparatus for Generating Oxidizing Agents

Abstract

Contemplated devices and methods include an electrolytic cell having a cathode and a carbon felt anode, wherein the carbon felt anode is configured as a flow-through anode for an aqueous solution in which a contaminant is dissolved or dispersed. The cell is operated at a current density that promotes formation of oxidizing species in neutral pH to thus destroy the contaminant and at a flow rate sufficient to prevent oxidative damage of the carbon felt.

1 . A method of treating an aqueous solution, comprising:
 providing an electrolytic cell having an anode in an anode compartment, a cathode in a cathode compartment, and a diaphragm separating the anode compartment from the cathode compartment to thereby fluidly isolate the anode compartment from the cathode compartment;   wherein the anode comprises a carbon felt that is conductively coupled to an electrical connector such that a flow path is formed to allow flow of the aqueous solution through the carbon felt;   moving the aqueous solution through the anode compartment such that substantially the entire solution passes through the carbon felt from one side to another side; and   operating the electrolytic cell at a current density effective to generate oxidative species from the aqueous solution in an amount sufficient to oxidize a contaminant in the aqueous solution.   
   
   
       2 . The method of  claim 1  wherein the carbon felt is prepared from carbonized organic textile fibrous felts. 
   
   
       3 . The method of  claim 1  wherein the carbon felt has a surface area of at least about 800-1200 m 2 /g. 
   
   
       4 . The method of  claim 1  wherein the flow path has a length of between 0.1 cm and 10 cm. 
   
   
       5 . The method of  claim 1  wherein the flow path has a length of between 0.5 cm and 5 cm. 
   
   
       6 . The method of  claim 1  wherein the aqueous solution has a pH of between 5.5 and 8.5. 
   
   
       7 . The method of  claim 1  wherein the aqueous solution has a pH of between 6.5 and 7.5. 
   
   
       8 . The method of  claim 1  wherein the aqueous solution passes through the carbon felt at a flow rate of 0.1 ml/cm 3 *min to 10 ml/cm 3 *min. 
   
   
       9 . The method of  claim 1  wherein the aqueous solution passes through the carbon felt at a flow rate of 0.5 ml/cm 3 *min to 3 ml/cm 3 *min. 
   
   
       10 . The method of  claim 1  wherein the current density is between 10 mA/cm 2  and 500 mA/cm 2 . 
   
   
       11 . The method of  claim 1  wherein the current density is between 30 mA/cm 2  and 100 mA/cm 2 . 
   
   
       12 . The method of  claim 1  wherein the cell is continuously operated for at least 6 hours without apparent oxidative damage to the carbon felt. 
   
   
       13 . The method of  claim 1  wherein the cell is continuously operated for at least 24 hours without apparent oxidative damage to the carbon felt. 
   
   
       14 . The method of  claim 1  wherein the cell is continuously operated for at least 48 hours without apparent oxidative damage to the carbon felt. 
   
   
       15 . The method of  claim 1  wherein the oxidative species is selected from the group consisting of ozone, hydrogen peroxide, a hydroxy radical, an oxygen ion, singlet oxygen, and a superoxide anion. 
   
   
       16 . The method of  claim 1  further comprising a step of recycling at least part of the aqueous solution back to the anode compartment after the solution has passed through the carbon felt. 
   
   
       17 . The method of  claim 1  wherein the contaminant in the aqueous solution is selected from the group consisting of a bacterium, a spore, a virus, a eukaryotic cell, an optionally halogenated aromatic organic compound, and a dye.