1. Industrial Applications
Hydrogen peroxide (H2O2) is a strong oxidizing agent that is used in a variety of industrial applications, including paper pulp bleaching; textile bleaching; semiconductor manufacture; and synthesizing peroxygen compounds, such as sodium percarbonate and peracetic acid. Hydrogen peroxide is found in consumer goods such as toothpaste and mouthwash. It is also widely used as a sterilizing agent in aseptic packaging lines.
2. Hydrogen Peroxide Water Treatment and Wastewater Applications
Hydrogen peroxide may be used as a component in advanced oxidation processes where it is combined with ozone or UV light to generate highly reactive oxygen radicals that are effective at breaking down refractory organic compounds. Hydrogen peroxide is used to control odors caused by hydrogen sulfide, mercaptans, amines, and aldehydes in waste streams and to reduce loadings of organic and inorganic compounds that contribute to the ratio of biochemical oxygen demand to chemical oxygen demand (BOD/COD).
In addition, H2O2 is present in the formulations of peracetic acid (PAA) that may be used as a final disinfectant in wastewater treatment as an alternative to chlorination. Peracetic acid does not form chlorinated DBPs. Although H2O2 is present in the formulation, PAA is considered to be the active component for disinfection in wastewater.1,2
3. Fate and Transport
Trace amounts of hydrogen peroxide occur widely in nature and are produced naturally through photochemical processes and by metabolic processes in living organisms. Hydrogen peroxide is not known to bioaccumulate or persist in the environment more than a few days.3 The degradation products of hydrogen peroxide (water and oxygen) are nontoxic.
4. Selection of Method
The colorimetric method (4500-H2O2 B) is suitable for measuring hydrogen peroxide in the presence of PAA.
The method, which takes about 1 minute, is based on the ferric thiocyanate reaction. Under acidic conditions, H2O2 oxidizes ferrous iron to the ferric state resulting in the formation of an orange-colored ferric thiocyanate complex. The resulting color intensity is linearly proportional to the H2O2 concentration. To prevent false positive bias, a modification to the procedure must be made if measuring H2O2 in the presence of PAA. In this case, the sample is pretreated with potassium iodide. PAA reacts with iodide to produce iodine and acetic acid. Acetic acid, iodine, and excess iodide do not react with the ferrous iron in the reagent.
5. Sampling and Storage
To minimize H2O2 decomposition during sampling, avoid agitation and exposure to sunlight and other strong light. Analyze immediately after sampling; do not store H2O2 samples.