Oxygen generation from water

Okuno Y, Yonemitsu O, Chiba Y (1983) Manganese dioxide as specific redox catalyst in the photosensitized oxygen generation from water. Chem Lett 12 815-818... 

Anodic processes may occur by direct electrochemical reaction of the waste at the anode, or by indirect oxidation when an oxidizing agent is generated in the waste stream. For example, oxygen and ozone may be generated from water in the waste stream, or the addition of sodium chloride to the waste stream can be used to generate free chlorine or hypochlorite at the anode. In addition, metal ions of higher valence states can be produced at the anode to oxidize wastes. 

In the initial part of the sorption process, at small volumes of raw water of about 2,900 BV, as well as at the large volumes of over 13,500 BV, the NOM removal from chlorinated water is more efficient. In the first part of the operation cycle, the nascent oxygen generated from h3rpochloric add causes NOM degradation and more efficient sorption of the degradation produds of HAs and FAs compared to the native humins present in non-chlorinated water. These processes take place in the environment of the ion competition, as described by authors... 

Oxygen photogeneration from water appears to be a less important process to study, because the H2-evolution system nominally provides a route to generate a useful fuel via alternative energy sources. Titania and WO3 are the two most commonly used semiconductor sensitisers for water oxidation. In some cases an oxygen catalyst seems not to be needed, especially, if WO3 is used as photosensitiser. 

In the completion or the end of charging, the storage battery containing an aqueous electrolyte causes electrolysis reaction of the water. Then oxygen generates from the positive electrode... 

Petrochemical units generate waste waters from process operations such as vapor condensation, from cooling tower blowdown, and from stormwater runoff. Process waste waters are generated at a rate of about 15 cubic meters per hour (m /hr), based on 500,000 tpy ethylene production, and may contain biochemical oxygen demand (BOD) levels of 100 mg/1, as well as chemical oxygen demand (COD) of 1,500 to 6,000 mg/1, suspended solids of 100 to 400 mg/1, and oil and grease of 30 to 600 mg/1. Phenol levels of up to 200 mg/1 and benzene levels of up to 100 mg/1 may also be present. 

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