Atmospheric potential oxygen

Let us compare M-ZSM-5 zeolites with M = H+, Li+, Na, K+, Rb, Cs, AF+, on one hand, and organic electron donors of variable ionization potentials, on the other. Zeolite H-ZSM-5 generates cation-radicals from substrates with an oxidation potential of up to 1.65 V (Ramamurthy et al. 1991). The naphthalene sorption by Al-ZSM-5 zeolites calcified in an atmosphere of oxygen or argon leads to the appearance of two occluded particles—the naphthalene cation-radical and isolated electron. Both particles were fixed by ESR method. Back reaction between the oppositely charged particles proceeds in an extremely slow manner and both the signals persist over several weeks at room temperature (Moissette et al. 2003). 

In the presence of water vapour and/or carbon dioxide in the oxidizing atmosphere, the oxygen potentials are not changed but the pore now contains the species H2, H2O, CO, and CO2, from the atmosphere. These species set up H2-H2O and CO-CO2 redox systems in the pore to conform to the oxygen potentials according to Equations (7.5) and (7.6),... 

Potentially oxygen-deficient atmospheres in confined spaces... 

Whenever personnel are working in potentially oxygen-deficient atmospheres (as with inert gases), they must be equipped with a portable SCBA or air-line breathing equipment and have a person standing outside of the area to signal if an emergency should occur. 

SB-2 Oxygen-Deficient Atmospheres, Depletion of the oxygen content in air by combustion or displacement with inert gas is a potential hazard to personnel throughout industry. This bulletin deals with recommended practices for the protection of personnel working in a potentially oxygen-deficient atmosphere. Supplemental to CGA P-14. (2 pages)... 

In normal practice, inhibitors such as hydroquinone (HQ) [123-31 -9] or the monomethyl ether of hydroquinone (MEHQ) [150-76-5] are added to acrylic monomers to stabilize them during shipment and storage. Uninhibited acrylic monomers should be used prompdy or stored at 10°C or below for no longer than a few weeks. Improperly iahibited monomers have the potential for violent polymerizations. HQ and MEHQ require the presence of oxygen to be effective inhibitors therefore, these monomers should be stored in contact with air and not under inert atmosphere. Because of the low concentration of inhibitors present in most commercial grades of acrylic monomers (generally less than 100 ppm), removal before use is not normally required. However, procedures for removal of inhibitors are available (67). 

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