Arsenic oxide poisoning

The element is a steel gray, very brittle, crystalline, semimetallic solid it tarnishes in air, and when heated is rapidly oxidized to arsenous oxide with the odor of garlic. Arsenic and its compounds are poisonous. 

Fire Hazards - Flash Point Not flammable Flammable Limits in Air (%) Not flammable Fire Extinguishing Agents Not pertinent Fire Extinguishing Agents Not To Be Used Not pertinent Special Hazards of Combustion Products Poisonous, volatile arsenic oxides may be formed in fires Behavior in Fire Not pertinent Ignition Terrqterature Not pertinent E/cc/nca/Hazard Not pertinent Burning Rate Not pertinent. 

The platinum catalyst used in the oxidation of sulphur dioxide (contact process) is poisoned by arsenic oxide (As203). 

As Mr Blandy s health was deteriorating, a doctor was summoned. He was of the opinion that the patient was being poisoned and that Mary s position would be serious if he were to die. The contents of the soup pan and the white powder were examined by another doctor. Dr Addington, who carried out a series of tests and compared the results with those of a known sample of white arsenic. These tests were very thorough and included adding the powder to water, sprinkling it on red-hot iron, and adding various other substances such as syrup of violets and spirit of vitriol to a solution of the sediment. The doctor observed an exact similitude between the results with the sediment and the known sample of arsenic oxide. 

Oxidizer, Poison, Corrosive SAFETY PROFILE Poisonous and corrosive. Very reactive, a powerful oxidizer. Explosive or violent reaction with organic materials, water, acetone, ammonium halides, antimony, antimony trichloride oxide, arsenic, benzene, boron, bromine, carbon, carbon monoxide, carbon tetrachloride, carbon tetraiodide, chloromethane, cobalt, ether, halogens, iodine, powdered molybdenum, niobium, 2-pentanone, phosphoms, potassium hexachloroplatinate, pyridine, silicon, silicone grease, sulfur, tantalum, tin dichloride, titanium, toluene, vanadium, uranium, uranium hexafluoride. 

Many substances that might be considered toxic are in fact essential to life, for example the heavy metals Co, Cu, Fe, Se, Zn. Thus, there is a relationship between concentration of the substance and the health response it invokes. An element is essential to life when a deficient intake of the element consistently results in impairment of a life function from optimal to suboptimal (Fig. 1a). Moreover, when physiological levels of this element, but not of others, are supplemented or restored, the impairment is cured and optimal health is restored (Fig. 1a). By contrast, non-essential elements do not produce a positive health response. An organism may tolerate low concentrations of some non-essential elements (Fig. 1b). Even dangerous poisons such as arsenic oxide (As203) can be tolerated... 

Arsenic derivatives were used as pesticides and as paint (by artists the bright yellow pigment, royal yellow, which was favoured by seventeenth-century Dutch painters, is known to oxidise slowly to the deadly compound arsenic oxide), and also in wallpapers (during the nineteenth century, most wallpaper was printed with emerald green containing copper arsenate, which could easily be transformed into the deadly gas methylarsine, by a particular mould that developed when the walls became damp, causing arsenic poisoning. 

HTS catalyst consists mainly of magnetite crystals stabilized using chromium oxide. Phosphoms, arsenic, and sulfur are poisons to the catalyst. Low reformer steam to carbon ratios give rise to conditions favoring the formation of iron carbides which catalyze the synthesis of hydrocarbons by the Fisher-Tropsch reaction. Modified iron and iron-free HTS catalysts have been developed to avoid these problems (49,50) and allow operation at steam to carbon ratios as low as 2.7. Kinetic and equiUbrium data for the water gas shift reaction are available in reference 51. 

Catalytic Oxidation. Catalytic oxidation is used only for gaseous streams because combustion reactions take place on the surface of the catalyst which otherwise would be covered by soHd material. Common catalysts are palladium [7440-05-3] and platinum [7440-06-4]. Because of the catalytic boost, operating temperatures and residence times are much lower which reduce operating costs. Catalysts in any treatment system are susceptible to poisoning (masking of or interference with the active sites). Catalysts can be poisoned or deactivated by sulfur, bismuth [7440-69-9] phosphoms [7723-14-0] arsenic, antimony, mercury, lead, zinc, tin [7440-31-5] or halogens (notably chlorine) platinum catalysts can tolerate sulfur compounds, but can be poisoned by chlorine. 

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