Benefits of UV-assisted wet oxidation irreversible removal of organic pollutants waste material free method does not increase in salinity can be used by chemical entry include persistent connections treatable easy process control, high reliability even for discontinuous streams well with biological processes can be combined by use of vacuum-UV lamps effective oxidant using UV-assisted Wet oxidation - What is it?
With the aid of wet oxidation, organic substances in water using strong oxidants such as ozone or hydrogen peroxide, are completely oxidized to carbon dioxide, water and possibly other substances. The effectiveness of the method depends essentially on the oxidation potential of the oxidizing agent. The following table provides an overview of the oxidation potentials of some oxidants.
- Oxidants electro-chemical symbol. Potential (V) potential rel. Chlorine (%)
- Fluorine F2 3.06 2.25
- Hydroxyl radical OH * 2.80 2.05
- Oxygen atom O * 2.42 1.78
- Ozone O3 2.08 1.52
- Hydrogen peroxide H2O2 1.78 1.30
- Hypochlorous acid HClO 1.49 1.10
- Chlorine Cl2 1.36 1.00
- Chlorine dioxide ClO2 1.27 0.93
- Oxygen O2 1.23 0.90
As can be seen from the table, the hydroxyl radical has a relatively high oxidation potential and is therefore best suited for wet oxidation. By UV radiation in the wavelength range between 200 nm and 280 nm is an effective way to divide to produce hydrogen peroxide and hydroxyl radicals. To do this, the hydrogen molecule adsorb the incident photon.
Even with the use of ozone as an oxidant can be formed by UV radiation hydroxyl radicals. For this reaction, however, two reaction steps are required. This means, in this case, two photons required for a molecule.
In parallel with the reactions of hydroxyl radicals to produce the incident photons in a position to direct reactions in the organic molecule are causing. Furthermore, recombination can take place. The wet oxidation reaction that is stimulated by photochemical processes is subject to various factors that can influence each other. The main factors are:Type and concentration of oxidizing agent concentration of the oxidizing compounds wavelength spectrum and intensity is of the UV radiation concentration of active oxidizing radicals (hydroxyl radicals) Because of the interactions between the various factors influencing the response result not easily influenced positively by changing a parameter. Rather, there is an optimal parameter range, which is different for each problem case. For this reason, UV wet oxidation processes are implemented only technically successful if the technology in the laboratory and may have been tested in a pilot trial.