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.

Description

[0001]This application claims priority to our copending U.S. provisional patent application with the Ser. No. 60 / 697,455, which was filed Jul. 7, 2005.FIELD OF THE INVENTION[0002]The field of the invention is devices and methods for electrochemical generation of oxidizing species, especially as they relate to anodic in situ generation of such species in a fluid.BACKGROUND OF THE INVENTION[0003]Oxidative species, including ozone, hypochlorite, hydrogen peroxide, persulfate, chlorine dioxide, and hydroxyl radicals are frequently used to sterilize water and destroy toxic organic compounds. Among such oxidative species, some exhibit sufficient chemical stability in water to keep the water sterile over relatively long periods, while other oxidative species (e.g., ozone) have relatively short half lives in water, which potentially allows re-infection of previously sterilized water.[0004]Among the most common sterilizing agents, hypochlorite (OCl−) is typically prepared by adding chlorine ...

AI Technical Summary

Benefits of technology

[0008]The present invention is directed to various devices and methods of electrochemical generation of oxidative species in an aqueous solution having typically neutral pH using a carbon felt flow-through anode under conditions that reduce, and more typically eliminate oxidative damage to the anode while generating the oxidative species in an amount effective to reduce and / or destroy a contaminant.

Problems solved by technology

Unfortunately, hypochlorite is also known to react with naturally occurring organic materials, including fulvic and humic acids (e.g., present in soil and sediments in lakes, rivers, and ground water) to form chloromethanes and other toxic byproducts.

Moreover, storage of chlorine gas or solutions of sodium hypochlorite on site for dosing into water streams presents a potential hazard, and dosing requires an at least somewhat experienced operator.

Yet another undesirable effect of chlorination of water is that hypochlorite produces a relatively bad taste in the treated water.

Ozone is chemically more aggressive as a sterilizing agent, but is often more expensive and has a relatively short half life in water.

Unfortunately, photolytic hydroxyl radical generation is often limited by turbidity or other compounds that absorb and / or scatter incident light.

However, while most of known devices provided at least some satisfactory results, other disadvantages still remain.

Among other things, electrode materials are either often relatively expensive, difficult to replace by an inexperienced user, and / or typically require relatively large amounts of energy to provide efficient sterilization / decontamination.

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