Rotten-egg odor

Physical Properties. Hydrogen sulfide, H2S, is a colorless gas having a characteristic rotten-egg odor. The physical properties of hydrogen sulfide are given in Table 2. 

Fuel sulfur is also responsible for a phenomena known as storage and release of sulfur compounds. Sulfur oxides (S02,S02) easily react with ceria, an oxygen storage compound incorporated into most TWC catalysts, and also with alumina. When the air/fuel mixture temporarily goes rich and the catalyst temperature is in a certain range, the stored sulfur is released as H2S yielding a rotten egg odor to the exhaust. A small amount of nickel oxide incorporated into the TWC removes the H2S and releases it later as SO2 (75—79). 

Corrosion products and deposits. All sulfate reducers produce metal sulfides as corrosion products. Sulfide usually lines pits or is entrapped in material just above the pit surface. When freshly corroded surfaces are exposed to hydrochloric acid, the rotten-egg odor of hydrogen sulfide is easily detected. Rapid, spontaneous decomposition of metal sulfides occurs after sample removal, as water vapor in the air adsorbs onto metal surfaces and reacts with the metal sulfide. The metal sulfides are slowly converted to hydrogen sulfide gas, eventually removing all traces of sulfide (Fig. 6.11). Therefore, only freshly corroded surfaces contain appreciable sulfide. More sensitive spot tests using sodium azide are often successful at detecting metal sulfides at very low concentrations on surfaces. 

Hydrogen Sulfide HjS Cause of rotten egg odor corrosion Aeration, chlorination, highly basic anion exchange... 

Hydrogen sulfide gas Hydrogen sulfide is a gas with a rotten egg odor. This gas is produced under anaerobic conditions. Hydrogen sulfide is particularly dangerous because it dulls your sense of smell so that you don t notice it after you have been around it for a while and because the odor is not noticeable in high concentrations. The gas is very poisonous to your respiratory system, explosive, flammable, and colorless. 

If you ve worked with H2S in the laboratory, you won t soon forget its rotten-egg odor. In a sense, it s fortunate that hydrogen sulfide has such a distinctive odor. This gas is highly toxic, as poisonous as HCN. At a concentration of 10 parts per million, H2S can cause headaches and nausea at 100 ppm it can be fatal. 

Colorless liquid with a strong, disagreeable, skunk-like or rotten egg odor. Extremely flammable liquid or gas. An experimentally determined odor threshold concentration of 1 ppbv was reported by Leonardos et al. (1969). Katz and Talbert (1930) reported experimental detection odor threshold concentrations in the range 0.66-7.6 pg/m (0.26 to 3.0 ppbv). 

Hydrogen sulfide (H S) is one of the most important compounds of sulfur. It is a colorless gas with a foul, rotten-egg odor. It is well known in school laboratories when sulfur is being studied. It is produced by the reaction of hydrochloric acid with iron sulfide (2HC1 + FeS — FeClj + HjS). 

Colorless gas characteristic odor of rotten eggs odor threshold Ippm sweetish taste fumes in air flammable gas, bums with a pale blue flame refractive index at 589.3nm, 1.000644 at 0°C and 1 atm density 1.539 g/L at 0°C critical temperature 100.4°C critical pressure 88.9 atm liquefies at -60.7°C solidifies at -85.5°C velocity of sound 289 m/sec in H2S gas slightly soluble in water (0.4% at 20° C) pH of a saturated aqueous solution 4.5 slightly acidic diffusivity in water at 16°C, 1.77x10 cm /sec soluble in carbon disulfide, methanol, acetone very soluble in N-methylpyrrolidinone and alka-nolamines (salt formation occurs salt dissociates on heating) liquid H2S dissolves sulfur and SO2. 

Malo-lactic Bacteria. Promptly separating the new wine from the thick layer of yeast and pulp particles is most important. Many wines are spoiled by procrastination. The yeast cells, if left in a thick layer, will begin to digest themselves and produce bad-smelling materials. Some breakdown products from this action have odors reminiscent of rotten eggs—the odor of hydrogen sulfide. Once the wine has acquired a rotten egg odor it is very difficult to remove it. 

Formula H2S MW 34.08 CAS [7783-06-4] ocurs in natural gas and sewer gas formed when metal sulfides react with dilute mineral acids colorless gas with rotten egg odor liquefies at -60.2°C solidifies at 85.5°C slightly soluble in water (4000 mg/L at 20°C) aqueous solution unstable, absorbs oxygen and decomposes to sulfur highly toxic and flammable. 

Sulfur also is found as sulfide minerals in combination with iron or base metals (e g-, pyrites) and as sulfates in combination with alkali metals and alkaline earths (e.g., gypsum). Hydrogen sulfide, with its rotten egg odor, is the primary sour component of sour gas. Crude oil and coal contain a variety of complex sulfur-containing organic species. These sulfur compounds are removed from the liquid fuels by treatment with hydrogen to convert the sulfur to hydrogen sulfide, which is taken off in the gas stream. The recovery of sulfur from sour fuels for environmental reasons is the largest source of sulfur today. 

Sulfide produces an undesirable rotten-egg odor and is toxic when in the HjS gas form. Since the first pKa of H2S is 7.24, it is necessary to maintain pH 9 or above to completely prevent evolution of H2S gas (Fig. 12.7). Although excess H2S is necessary for the precipitation reaction, the excess must be kept to a minimum. Furthermore, although metal-sulfide solubility with respect to pH exhibits U-shaped behavior (Fig. 12.8), its solubility within the desirable pH range is extremely small (MCLs are met) (Fig. 12.9). Precipitation of metal-sulfides is normally carried out using Na2S or NaHS. However, not all metals precipitate effectively by sulfide. For example, chromium (Cr3+) precipitates effectively as a hydroxide rather than sulfide. 

Few agents are acutely toxic to the olfactory receptors. Hydrogen sulfide, as mentioned earlier, causes rapid olfactory fatigue, and the normal rotten egg odor quickly vanishes allowing prolonged exposure to this potentially fatal mitochondrial toxin. Occupational exposure to several solvents and metals has been associated with olfactory dysfunction (Table 4). 

Wetlands of humid climatic zones often emit H2S, as is evident from the rotten-egg odor of marshes and swamps. As long as the dominant exchangeable base cations are Ca " and Mg ", which is the case in most freshwater wetlands, H2S formation should not cause the soils to become strongly alkaline. In these nonsodic soils, alkalinity generated by reduction forms precipitates of Ca (and Mg) carbonates. The low solubility of these carbonates prevents the pH from rising much above 8. In sodic soils, however, reaction 7.64 causes alkalinity to build up in the form of soluble Na carbonates (see Chapter 8, Section 8.1). 

Victims may not detect its well-known rotten eggs odor. Exposed workers can experience knockdowns, or losses of consciousness, described by observers as resembling turning off the switch of a mechanical doll (Guidotti 1994). Oil patch folklore held that after a few knockdowns, victims became simple in the head (Guidotti 1994). 

Hydrogen snlfide has the same kind of adverse action on respiration as hydrogen cyanide. Althongh most persons can detect the bnmt-almond odor of hydrogen cyanide gas, and can initially detect the rotten-egg odor of hydrogen sulfide gas, the latter quickly deadens the olfactory nerve, so that hydrogen sulfide is especially... 

With its sickly yellow color and rotten-egg odor, the ancients used to call it brimstone and mined it for religious purposes. In modern times, we call it sulfur and use it to make countless useful items. 

PHYSICAL PROPERTIES Colorless liquid when pure, yellow when impure sweet odor when pure, rotten egg odor when impure soluble in alcohol, benzene, ether, water MP (-111.5°C) BP (46.5°C) DN (1.2632 g/ml at 20°C) ST (32 dynes/cm) VP (352.6 mm Hg) OT (0.1-0.2 ppm). 

II. Toxic dose. The characteristic rotten egg odor of hydrogen sulfide is detectable at concentrations as low as 0.025 ppm. The recommended workplace limit (ACGIH TLV-TWA) is 10 ppm (14 mg/m ) as an 8-hour time-weighted average, with a short-term exposure limit (STEL) of 15 ppm (21 mg/m ). The Federal OSHA permissible exposure limit (PEL) is 20 ppm as a 15-minute ceiling during an 8-hour workday. Marked respiratory tract irritation occurs with levels of 50-100 ppm. Olfactory nerve paralysis occurs with levels of 100-150 ppm. The level considered immediately dangerous to life or health (IDLH) is 100 ppm. Pulmonary edema occurs at levels of 300-500 ppm. Levels of 600-800 ppm are rapidly fatal. 

Colorless liquid with an offensive rotten egg odor. Odor and irritation are good warning properties. 

To illustrate the use of an emission factor, let us turn to the fish-canning industry. From AP-42, section 9.13.1-7 and Table 3, entitled Uncontrolled Emission Factors for Fish Canning and Byproduct Manufacture, emission factors are shown for particulate emissions, trimethylamine (fish odor), and hydrogen sulfide (rotten egg odor). Emissions from the fish scrap cookers for both fresh fish and stale fish are shown. Notice that the particulate emissions are negligible for the cookers. Trimethylamine (fish odor) has an emission factor of 0.3 Ib-tiimethylamine/ton of fresh fish cooked. If we are cooking 5 tons of fresh flsh/hr, then the uncontrolled fish odor emission to the atmosphere is 0.3 Ib-trimethylamine/ton of fresh fish cooked X 5 tons of fresh fish/hr = 1.5 Ib-trimethylamine/ hr. Since the chemical responsible for typical fish odor is trimethylamine, 1.5 Ib/hr will certainly be noticed by residents noses downwind of the plant. 

Anoxic conditions favor sulfur instead of oxygen as an oxidizing agent Hydrogen sulfide (HjS) is formed that has a rotten egg odor. Raising pH reduces the concentration of H2S compared with other sulfide species, thereby reducing odor. 

Empirical C2H4NS2 Na Properties Wh. cryst. solid pungent rotten egg odor sol. 722 g/l in water 20 C mod. sol. in ethanol insol. in mostorg. soivs. m.w. 129.18 Toxicology LD50 (oral, male rat) 1891 mg/kg, (dermal, rabbit) > 3074 mg/kg poison by ing. mod. toxic by skin contact si. skin and mild eye irritant mucous membrane irritant harmful if swallowed or inhaled may be fatal if absorbed thru skin causes violent vomiting and shock when accompanied by alcohol intake... 

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