Environment hydrogen

Waembaum G, Wallin I. 1979. Hazards in the work environment—hydrogen sulfide. ScandJWork Environ Health 5 31-34. 

The immersible hydrogen sensor (IHS-12 in Fig. 29) can be used to quantify hydrogen uptake by directly immersing it in the corrosive environment. Hydrogen uptake can also be measured under cathodic protection. 

Fig. 6.4.9. Brittleness of 0.6% MgO modified corundum sintered at 2073 K in environment hydrogen (/), argon (2), air (3), ammonia (4), nitrogen (5) and oxygen (6). (After Pavlushkin, 1961)...

Serpone, N. Lawless, D. Terzian, R. Minero, C. Pelizzetti, E. Heterogeneous photocatalysis Photochemical conversion of inorganic substances in the environment Hydrogen sulfide, cyanides, and metals. In Photochemical Conversion and Storage of Solar Energy, E. Pelizzetti, M. Schiavello, eds., Kluwer Acad. Publ. Dordrecht, The Netherlands, 1991. 

In a reducing environment hydrogen atoms will scavenge the oxygen atoms from molecules with NO bonds. This might be the reason that molecules, such as HCNO, N2O are absent in interstellar space or have fairly low abundances such as NO. 

Quite often, the bisulfite product is isolated and purified before the treatment with alkali cyanide, particularly in the conversion of aromatic aldehydes since their bisulfite compounds are easily manipulated. The preparation of aromatic cyanohydrins from their bisulfite products is advantageous since benzoin formation, which is catalyzed by alkali cyanides, is largely avoided. Furthermore, because of the basic environment, hydrogen cyanide fumes are curtailed. 

NETL has been actively investigating through both experimental and computational studies the potential of Pd-Cu alloys because of their potential applicability for gasifier and post-gasifier water-gas shift (WGS) membrane reactors and similar harsh environment hydrogen separation applications. Recent computational studies by Sholl and Alfonso have focused on the prediction of alloy membrane permeability values and the interaction of S with potential membrane materials . Our experimental studies on the permeability of a series Pd-Cu alloys in pure hydrogen and in the presence of H2S have also been recently reported . 

The 1998 Oxford Illustrated Dictionary defines pollute as to contaminate or defile (the environment). Hydrogen, when combined (burned, oxidized) with the air s oxygen, produces only water plus minuscule amounts of oxides of nitrogen, inevitable byproducts of any atmospheric burning process. Water doesn t pollute. 

When mixed with water, small amounts of nonpolar substances are excluded from the solvation network of the water that is, they coalesce into droplets. This process is called the hydrophobic effect. Hydrophobic ( water-hating ) molecules, such as the hydrocarbons, are virtually insoluble in water. Their association into droplets (or, in larger amounts, into a separate layer) results from the solvent properties of water, not from the relatively weak attraction between the associating nonpolar molecules. When nonpolar molecules enter an aqueous environment, hydrogen-bonded water molecules attempt to form a cagelike structure around... 

Sulfur compounds (H2S, SO2, organic sulfur) Operating tern perature up to 400°C Measurement range 0.05-0.5 ppm Response time <1 min at 0.05 ppm Gas environment Hydrogen, CO, CO2, hydrocarbons, water vapor... 

A similar formulation was used by Holzbecher and Niitzmaim (2000). Due to the values of the dissociation constants = 10 and 10" at 25°C, cf. Sigg and Stumm, 1989) at nearly neutral or weak alkaline pH conditions (as recorded for most groundwater environments) hydrogen carbonate predominates as TIC species. 

The mechanisms of CO2 corrosion are well defined, but the reality inside a pipeline occurs when CO2 acts in combination with H2S, deposited solids, and other environments. Hydrogen sulfide is highly corrosive but in some cases forms a protective sulfide scale that prevents corrosion. Microorganisms can attach to pipe walls and... 

Withstand the chemical environment (hydrogen, air, water, coolant additives). 

The main aim of CaFCP is to reach California s goals for cleaner air and reduced greenhouse gases despite the need for full-function cars, pickups, vans, and sports utility vehicles (SUVs) that people want to drive and transit buses in which they want to ride. These vehicles must be comparable to or better than the vehicles driven today, and be better for the environment. Hydrogen-powered fuel-cell vehicles are an option for fulfilling these requirements. 

In the reduction processes in natural environments hydrogen ions H+ and oxygen O2 are most often involved, and the related reduction processes can be written as following ... 

In sour environments hydrogen sulfide is one of the main factors to consider because of the risk of SCC. Sulfides (S " HS H2S) adsorbed on the metal surface catalyze the absorption of atomic hydrogen. This changes the toughness and ductility of the material and causes considerable embrittlement. It is generally known that the susceptibility of steels to SCC increases above a strength of 800 MPa (Fig. 1-16). This has led to the practice of specifying a maximum material... 

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