OriginClear’s proprietary AOx™ is an emerging, next-generation AOP. It features two methods, both catalytic, for reducing pollutants through oxidation. These methods may be used singly or in combination, according to the application.
The oxidizing agents include Oxygen (O), Chlorine (Cl), Hydrogen Peroxide (H2O2) and Ozone (O3).
Hydroxyl Radical (OH•) is the most powerful oxidizing agent available, produced by the reaction of Hydrogen Peroxide and Ozone.
Direct and Indirect Oxidation
The first method is direct, by exchange of electrons between the anode and the pollutants.
The second is indirect, by generating strong reactive oxygen species (ROS) — most especially OH• — on the anode surface, i.e. in-situ generation of oxidizing species.
The presence of chloride ions in the treated solution may facilitate indirect bulk oxidation by the in situ electro-generation of active chlorines like hypochlorite, chlorine dioxide and chlorine, which could greatly enhance the overall electrochemical incineration of the organic pollutants.
Advanced Oxidation Processes are at their most effective when they generate the highly-reactive Hydroxyl Radical (OH•). However, not all contaminants are reactive to OH•.
A dual solution is needed, which AOx achieves by combining electro-oxidation processes:
- Anodic oxidation by generating the full range of reactive oxygen species (ROS), especially OH•.
- Oxidation with active chlorine (“mediated oxidation”), which complements OH• where it is ineffective.
In this scenario, AOx forms large quantities of anodically generated active chlorine species such as Cl2, HClO/ClO‾ and ClO2‾.
These can oxidize the organics in competition with ROS by direct electron transfer (DET) reactions (e.g., fluorinated organics).
Hydroxyl Radical (OH•) Scavenging
AOPs suffer from decreased efficiency in natural waters due to OH• scavenging. Presence of bicarbonate ions (HCO3−) can appreciably reduce the concentration of OH• due to scavenging processes that yield H2O and a much less reactive species, •CO3−.
AOx solves this issue. The design uses water oxidation to produce an acidic boundary layer at the anode surface; so that in this region, HCO3– is protonated to H2CO3 and therefore prevents OH• scavenging associated with HCO3–present in natural waters.