|Purification of Biogas (GTZ, 1985)|
Physical and chemical properties
Hydrogen sulphide (H2S) is a colourless, very poisonous
gas. It is inflammable and forms explosive mixtures with air (oxygen).
H2S has a characteristic smell of "rotten eggs". This odour is only
apparent in a small concentration range (0.05-500 ppm).
H2S is soluble in water forming a weak acid. A combustion product of H2S is SO2 . This makes the exhaust gases very corrosive (sulphuric acid) and contaminates the environment (acid rain).
H2S is very poisonous (comparable to hydrogen cyanide).
Lower toxic limit 10 ppm H2S.
1.2-2.8 mg H2S per lifer of air or 0.1% kills instantly.
0.6 mg H2S per lifer of air or 0.05% kills within 30 minutes to one hour.
H2S changes the red blood pigment; the blood turns brown to olive
in colour. The transport of oxygen is hindered. The person suffocates
"internally". The symptoms are irritation of the mucous membranes (including the
eyes), nausea, vomiting, difficulty in breathing, cyanosis (discoloration of the
skin), delirium and cramps, then respiratory paralysis and cardiac arrest. At
higher concentrations immediate respiratory paralysis and cardiac arrest are the
Even if a person survives poisoning, longterm damage to the central nervous system and to the heart remains.
Fresh air, artificial respiration; warmth, rest, transportation in an inclined position. There is a danger of suffocation if the patient is unconscious!
Artificial respiration. Analeptics. Further observation of symptoms, particularly the function of the circulatory and pulmonary systems. Beware of oedema of the larynx. Codeine may be administered for bronchitis as soon as the asphyctic stage is past. Oedema of the lungs during the latent period: treat prophylactically with high doses of prednisolone i.v. In addition, infusions of altogether 0.5 g THAM/kg. Absolute rest, warmth, infection prophylaxis, keep breathing passages free. Only small quantities of morphine. Combat anhydremia by peroral administration of fluids or rectoclysis.
Long-term exposure to very small amounts of H2S can lead to chronic poisoning. Symtoms: irritation of the mucous membranes, sensitivity to light, bronchitis, headaches, weariness, circulatory disturbances and loss of weight.