Chemical reactions of metal phosphides:
AlP + 3H2O → Al(OH)3 + PH3
Mg3P2 + 6H2O → 3Mg(OH)2+ 2PH3
PH3 (hydrogen phosphide) which is highly toxic to all forms of animal and human life, slightly heavier than air, excellent penetration properties and easy to aerate. Phosphide is a colorless gas with a carbide- or garlik-like odor.
Essential Properties of Phosphide:
Molecular Weight 34.0
Boiling Point 1/ – 87.4C
Specific Gravity 2/ 1.21
(Air = 1)
Lower Explosion Limit 3/ 1.79%
1/ Boiling point at 760 mm pressure.
2/ Values greater than 1.0 are heavier than air.
3/ Percent by volume of gas in air.
Formulations based on aluminium phosphide (AlP) are the mostly used products for the control of pests in storages, as well for rodents and other outdoor vertebrates.
Due to their characteristics, formulations based on magnesium phosphide (Mg3P2), are the fumigant of choice for quick fumigations even under suboptimal conditions.