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The hydroxyl radical has a very short in vivo half-life of approximately 10 −9 seconds and a high reactivity. [5] This makes it a very dangerous compound to the organism. [6] [7] Unlike superoxide, which can be detoxified by superoxide dismutase, the hydroxyl radical cannot be eliminated by an enzymatic reaction.
VHP is produced from a solution of liquid H 2 O 2 and water, by generators specifically designed for the purpose. These generators initially dehumidify the ambient air, then produce VHP by passing aqueous hydrogen peroxide over a vaporizer, and circulate the vapor at a programmed concentration in the air, typically from 140 ppm to 1400 ppm, depending on the infectious agent to be cleared. [6]
Hydroxyl radical (HO·) is generated by Fenton reaction of hydrogen peroxide with ferrous compounds and related reducing agents: Fe(II) + H 2 O 2 → Fe(III)OH + HO· In its fleeting existence, the hydroxyl radical reacts rapidly irreversibly with all organic compounds. superoxide (O − 2) is produced by reduction of O 2. [4]
In chemistry, a hydroxy or hydroxyl group is a functional group with the chemical formula −OH and composed of one oxygen atom covalently bonded to one hydrogen atom. In organic chemistry , alcohols and carboxylic acids contain one or more hydroxy groups.
Dusts also have upper and lower explosion limits, though the upper limits are hard to measure and of little practical importance. Lower flammability limits for many organic materials are in the range of 10–50 g/m 3, which is much higher than the limits set for health reasons, as is the case for the LEL of many gases and vapours. Dust clouds ...
As an example of dissociation, hydrogen peroxide can undergo homolytic cleavage, with the O−O bond cleaving to form two hydroxyl radicals. H 2 O 2 → 2 ·OH. Certain azo compounds (such as azobisisobutyronitrile), can also photolytically cleave, forming two alkyl radicals and nitrogen gas: RCH 2 −N=N−H 2 CR → 2 RCH 2 + N 2
Sulfur – ignition promoter, increases burn rate; increases sensitivity to temperature, impact and friction, dangerous in combination with chlorates; commonly used with nitrates; used as an additive; may contain residual acids, combination with carbonates or other alkaline stabilizers is advised in acid-sensitive compositions
The Kelvin water dropper, invented by Scottish scientist William Thomson (Lord Kelvin) in 1867, [1] is a type of electrostatic generator. Kelvin referred to the device as his water-dropping condenser. The apparatus is variously called the Kelvin hydroelectric generator, the Kelvin electrostatic generator, or Lord Kelvin's thunderstorm.