hydrogen sulfide

Colorless and highly toxic acid gas

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synonym H2S (H2S) generally refers to hydrogen sulfide

Hydrogen sulfide (H two S) It is a colorless and highly toxic acid gas, which belongs to an inorganic compound. It has no obvious smell at high concentration, strong rotten egg smell at low concentration, and sulfur smell at very low concentration. It is a by-product in many industrial processes, such as natural gas refining, oil refining, waste water treatment and paper industry^[2] 。 It is also produced in nature through the decomposition of organic matter and the metabolic activities of some microorganisms. The density of hydrogen sulfide is slightly higher than that of air, which can gather in low-lying areas and form potential hazardous areas. At low concentrations, it is toxic to human body, and inhalation of high concentrations of hydrogen sulfide will quickly kill. By inhibiting the oxidative phosphorylation of cells, it impedes cell respiration and leads to cell death. Hydrogen sulfide is irritant to eyes, respiratory system and nervous system, and may cause eye irritation, headache, cough and dyspnea when exposed to low concentration.

Hydrogen sulfide can be dissolved in water, alcohol and petroleum solvents. In addition, hydrogen sulfide can form explosive mixture with air, which will cause combustion and even explosion when encountering open fire or high heat.

In industrial applications, hydrogen sulfide is used in the flotation process of sulfide ores, and is also an important raw material for the production of sulfur and sulfuric acid. In addition, it is used as an analytical reagent in the laboratory, such as in the qualitative analysis of heavy metal ions. However, due to its high toxicity and corrosiveness, handling hydrogen sulfide requires strict safety measures, including good ventilation, use of personal protective equipment and installation of gas detectors to prevent accidental exposure.

Chinese name: hydrogen sulfide
Foreign name: hydrogen sulfide
chemical formula: H two S
molecular weight: thirty-four point zero eight
CAS login number: 7783-06-4^[17]
EINECS login number: 231-977-3^[17]
Melting point: -85.5 ℃^[17]
Boiling point: -60.4 ℃^[17]
Appearance: Colorless, with rotten rotten egg like odor
Security description: S9； S16； S36； S38； S45； S61

Hazard description: R21
UN dangerous goods number: one thousand and fifty-three
GB No: twenty-one thousand and six^[17]
MDL No: MFCD00011444^[17]
RTECS No: MX1225000^[17]
BRN No: three million five hundred and thirty-five thousand and four^[17]
PubChem No: twenty-four million eight hundred and eighty-eight thousand two hundred and sixty-six^[17]
InChI: InChI=1/H₂S/h1H₂
Name of aqueous solution: Hydrosulfuric acid
Solubility: Soluble in water (dissolution ratio 1:2.6), ethanol, carbon disulfide, glycerin, gasoline, kerosene, etc.

catalog

one Physical and chemical properties
two Main purpose
▪ industrial production
▪ Environmental governance
▪ Physiological and pathological effects
three Chemical data
four Hazard description

Physical and chemical properties

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Molecular structure of hydrogen sulfide

molecular structure : The central atom S atom takes sp ³ Hybridization , electron pair configuration is tetrahedral, molecular configuration is V-shaped, H-S-H bond angle is 92.1 °, dipole moment 0.97 D, yes Polar molecule 。 Due to weak H-S bond energy, hydrogen sulfide decomposes at about 300 ℃.

Flash point: 260℃，

Saturated vapor pressure: 2026.5 kPa/25.5℃，

Solubility: Soluble in water (dissolution ratio 1:2.6), ethanol, carbon disulfide, glycerin, gasoline, kerosene, etc.

Critical temperature: 100.4 ℃, critical pressure: 9.01MPa.

Melting point: -85.5 ℃ Boiling point: -60.4 ℃

Danger signs : Class 2.1 flammable gas, Class 2.3 toxic gas.

Color and odor: Hydrogen sulfide is a colorless, highly toxic and acidic gas. At low concentrations, there is a special smell of rotten eggs. The olfactory threshold is 0.00041ppm. Even low concentrations of hydrogen sulfide will damage people's sense of smell. When the concentration is high, there is no smell (because high concentration of hydrogen sulfide can paralyze the olfactory nerve). It is not advisable to judge hydrogen sulfide gas by smell.

Relative density: Is 1.189 (15 ℃, 0.10133MPa). The density is greater than air, and it is easy to gather in low terrain places, such as pits and basements. If it is found in a place where hydrogen sulfide is known to exist, self-protection measures should be taken immediately. Whenever possible, work in upwind and high terrain^[1] 。

Explosion limit: It will explode when mixed with air or oxygen in an appropriate proportion (4.3%~46%). Therefore, the operation site containing hydrogen sulfide gas shall be equipped with hydrogen sulfide monitor^[10] 。

flammability: Completely dry hydrogen sulfide does not react with oxygen in the air at room temperature, but it can burn in the air when ignited. It burns during drilling and downhole blowout, with a burning rate of only about 86%. When hydrogen sulfide burns, it will produce blue flame and toxic sulfur dioxide gas, which will damage people's eyes and lungs. Generate SO when air is sufficient two And H two O^[10] 。

If the air is insufficient or the temperature is low, free S and H will be generated two O。^[1]

In addition to oxygen or air, hydrogen sulfide can also chlorine and Fluorine gas Medium burning.

Solubility : Hydrogen sulfide gas is soluble in water, ethanol and glycerol Medium, chemical properties are unstable. Slightly soluble in water, forming weak acid, called "hydrogen sulfuric acid". Its aqueous solution contains hydrogen sulfate HS - (at 18 ℃, the concentration is 0.01-0.1 mol/L, p K a =6.9) and sulfur ion S 2- 。 At first, it was clear Hydrosulfuric acid It will become turbid after being placed for a period of time, because hydrosulfuric acid will slowly react with oxygen dissolved in water to produce elemental sulfur insoluble in water.

acidic: Hydrogen sulfide is a kind of Binary weak acid 。 At 20 ℃, one volume of water can dissolve 2.6 volumes of hydrogen sulfide. The generated water solution is called hydrogen sulfuric acid, and the concentration is 0.1mol/L^[1] 。 The second ionization degree of hydrogen sulfide in water is quite low, so that sulfur ions can be detected by the instrument only when the hydroxyl concentration reaches at least 8mol/L:

Hydrogen sulfide has the following equilibrium in solution:

Reducibility: Hydrogen sulfuric acid has stronger Reducibility It is easy to be oxidized by air to release sulfur, which makes the solution turbid. In acid solution, hydrogen sulfide can make Fe 3+ Restore to Fe 2+ ，Br two Restore to Br －，I two Restore to I －，

Restore to Mn 2+ ，

Restore to Cr 3+ ，HNO three Restore to NO two It is usually oxidized to elemental sulfur.^[1] H two S can also reduce copper ions (Cu 2+ ）、 Selenite （H two SeO three ）, tetravalent polonium ion (Po 4+ ）Etc., such as:

Hydrogen sulfide gas can precipitate with metal, which is usually removed by precipitation. Generally, hydrogen sulfide gas is removed in the laboratory by introducing hydrogen sulfide gas Copper sulfate solution Medium, forming insoluble in general strong acid（ Non oxidizing acid ）Copper sulfide of:

But hydrogen sulfide and ferric sulfate During reaction, if the amount of hydrogen sulfide is small, only elemental sulfur can be generated, because Fe 3+ And S 2－ Will occur Redox reaction ：

Note: the sulfur of hydrogen sulfide is - 2, at the lowest price. But hydrogen is+1 and can drop to 0, so there is still Oxidizability , such as:

Centering reaction: Hydrogen sulfide can occur Homing reaction ：

Hydrogen sulfide is a reducing agent, sulfur dioxide is an oxidant, and sulfur is both an oxidation product and a reduction product.

Main purpose

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industrial production

In the field of industrial production, hydrogen sulfide is mainly used to produce sulfur and sulfuric acid, which is an indispensable raw material in many industrial processes^[12] 。 For example, sulfur can be recovered from hydrogen sulfide through Claus process, which is particularly important in refineries and natural gas processing plants to reduce environmental emissions^[11] 。 Sulfuric acid is produced through contact process, in which hydrogen sulfide is first converted into sulfur, and then sulfur dioxide is generated by burning sulfur, and then converted into sulfuric acid. Sulfuric acid is one of the most productive chemical products in the world, and is widely used in fertilizer, chemical synthesis, mineral processing and other fields.

Environmental governance

The application of hydrogen sulfide in environmental treatment is mainly reflected in its role in wastewater treatment and gas purification technology^[13] 。 In wastewater treatment, hydrogen sulfide can be converted into non-toxic sulfide by chemical precipitation, thus reducing water pollution. In addition, hydrogen sulfide also plays an important role in gas purification, especially in the process of oil refining and natural gas treatment. Hydrogen sulfide is removed from the gas by using absorbents or catalysts to meet environmental standards and improve product quality. For example, in heavy metal detection, hydrogen sulfide can be used to generate insoluble sulfide precipitation, so as to achieve qualitative and quantitative analysis of heavy metal ions such as lead and mercury.

Physiological and pathological effects

Hydrogen sulfide also shows potential value in biomedical research. For example, recent research shows that low concentration of hydrogen sulfide may play a role in regulating blood pressure, anti-inflammatory, neuroprotective, antioxidant and antibacterial. Machine experience synthesis H two S. It is called endogenous H two S. It and CO and NO are called the three chemical messenger molecules of nerve. H two S is the regulator of neurotransmitter, H two The reducibility of S can eliminate the reactive oxygen free radicals in the body and protect the nerves. H two S can relax blood vessels, play a role in relieving hypertension, reducing arteriosclerosis and myocardial damage, which provides a new idea for developing new treatment methods^[14] 。

Chemical data

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Reference value for drainage parameter calculation (XlogP): 0.5

Number of hydrogen bond donors: 1

Number of hydrogen bond receptors: 1

Number of rotatable chemical bonds: 0

Number of tautomers: 0

Topological molecule polar surface area (TPSA): 1

Number of heavy atoms: 1

Surface charge: 0

Complexity: 0

Number of isotope atoms: 0

Determine the number of atomic structure centers: 0

Number of uncertain atomic structure centers: 0

Determine the number of chemical bond structure centers: 0

Number of uncertain chemical bond structure centers: 0

Number of covalent bond units: 1

Hazard description

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Physical and chemical hazards

Flammable gas.

Properties and stability: It has great solubility in organic amine. It also has greater solubility in caustic solution. It burns in excess oxygen to generate sulfur dioxide and water, and generates water and free sulfur when oxygen supply is insufficient. Stable at room temperature. Soluble in water, the aqueous solution is weakly acidic, and will slowly become turbid when contacting with air due to oxidation and sulfur precipitation. Able to burn in air to produce blue flame and generate SO two And H two O. Generate S and H when air is insufficient two O。 Even dilute hydrogen sulfide has irritating effect on respiratory tract and eyes, and causes headache. When the concentration reaches 1mg/L or higher, it is dangerous to life, so the preparation and use of H two S should be carried out in the fume hood.

Toxicological data

Concentration in ppm	reaction
Over 1000	Instant sudden death ("shock like" death)
600 - 700 (0.06 - 0.07%)	Death in a short time
four hundred	Death within one hour
120 - 280	Acute poisoning within one hour
50 - 120	Olfactory paralysis
25 - 50	Tracheal irritation, conjunctivitis
zero point four one	Smell an unpleasant smell
zero point zero zero zero four one	People begin to smell bad smell

^[15-16]

Invasion route: inhalation.

Health hazard: hydrogen sulfide is an acute toxic substance. Inhaling a small amount of high concentration hydrogen sulfide can be fatal in a short time. Low concentration of hydrogen sulfide has effects on eyes, respiratory system and central nervous system. It is soluble in water, 1 at 0 ℃ mole Water can dissolve about 2.6 moles of hydrogen sulfide. The aqueous solution of hydrogen sulfide is called Hydrosulfuric acid It is a weak acid. When it is heated, hydrogen sulfide escapes from water. Hydrogen sulfide is a kind of Acute toxicity Inhaling a small amount of high concentration hydrogen sulfide can be fatal in a short time. Low concentration of hydrogen sulfide on eyes respiratory system and Central nervous system All have an impact.

Mice and rats inhale LC fifty ：634×10⁻⁶/1h、712×10⁻⁶/1h； Rats inhaled LC fifty ：444×10⁻⁶/4h。 Hydrogen sulfide is mainly absorbed through respiratory tract, and people inhale (70-150mg/m ³）/ (1~2h), respiratory tract and eye irritation symptoms appear, hydrogen sulfide can paralyze the olfactory nerve, and odor will not be smelled after 2~5min of inhalation. Inhalation (300mg/m ³）/ Acute eye irritation symptoms occurred within 1h, 6-8min, caused by slightly prolonged contact pulmonary edema 。 Inhalation of hydrogen sulfide can cause central nervous system Sometimes, due to stimulation and respiratory paralysis, it will eventually lead to death. In high concentration hydrogen sulfide, collapse will occur within a few seconds shock , can cause respiratory tract inflammation, pulmonary edema, and accompanied by headache, chest pain and dyspnea 。 There shall be no oxidizing combustible materials, acids or other corrosive materials near the hydrogen sulfide storage area. Avoid exposure to high temperatures.

Acute toxicity: LC fifty ：618mg/m ³ (444ppm) (inhaled by rats).

Subacute and chronic toxicity: rabbits inhale 0.01mg/L for 2h and 3 months every day, causing functional changes in the central nervous system, trachea a bronchial tube Mucosa irritation symptoms, pathological changes in cerebral cortex. Mice exposed to low concentration hydrogen sulfide for a long time have small airway damage.

Others: LCLo: 600ppm (inhalation for 30min).

In vivo process: hydrogen sulfide is an irritant gas, which can be absorbed almost all through the respiratory tract or through the skin. It is oxidized into non-toxic sulfate and Thiosulfuric acid Salt is excreted with urine, and part of free hydrogen sulfide is exhaled through the lungs, without accumulation in the body.^[2]

Pathogenesis:

1. High concentration of hydrogen sulfide in blood can directly stimulate Carotid sinus And aortic Chemoreceptor , causing reflex respiratory depression.

2. Hydrogen sulfide can directly act on brain, and low concentration plays an exciting role; High concentration plays an inhibitory role, causing coma , respiratory center and Vasomotor center Paralysis. Because hydrogen sulfide is Cytochrome oxidase Is a strong inhibitor of Mitochondrial intima The combination of ferric ion in oxidized cytochrome oxidase in the respiratory chain inhibits electron transfer and utilization of oxygen, causing intracellular hypoxia and intracellular asphyxia. Since brain tissue is most sensitive to hypoxia, it is most vulnerable to damage.

The above two effects occur quickly, both can cause sudden respiratory arrest, resulting in Shock like death 。 If contact can be stopped in time at the beginning of the disease, many cases can be recovered quickly and completely, possibly due to the rapid oxidation of hydrogen sulfide in the body Inactivation Therefore.

3. Secondary hypoxia is due to the decrease of blood oxygen content caused by factors such as apnea or pulmonary edema caused by hydrogen sulfide, which can aggravate the condition and perpetuate neurological symptoms Multiple organ failure 。

4. Hydrogen sulfide decomposes after encountering the water on the surface of eyes and respiratory tract mucosa, and reacts with alkaline substances in the tissue to produce hydrogen sulfide, sulfur and hydrogen ions, hydrogen sulfuric acid and sodium sulfide, which have strong irritation and corrosion effects on the mucosa and cause chemical inflammatory reactions of different degrees. In addition, intraventricular breathing can cause the most serious damage to deeper tissues and easily cause pulmonary edema.

5. The mechanism of myocardial damage, especially delayed damage, is still unclear. Occurrence of acute poisoning miocardial infarction It may be caused by the direct effect of hydrogen sulfide Vasospasm 、 Myocardial ischemia , edema, inflammatory infiltration and Cardiac myocyte Internal oxidation disorder.

Acute hydrogen sulfide poisoning The autopsy results of fatal cases are often related to the duration of the disease Cerebral edema 、 pulmonary edema , followed by myocardial disease. Generally, the corpse is obvious Cyanosis When dissecting, it emits hydrogen sulfide smell, blood is flowing, and viscera is slightly green. Cerebral edema Most commonly, there are spot hemorrhage, necrosis and Softening stove Etc; The degeneration of spinal nerve tissue can be seen. The autopsy of electric shock death showed nonspecific asphyxia.

Ecological data

Ecotoxicity: TLm: 0.0071~0.55mg/L (96h) (black headed fish); 0.0448~0.0478mg/L (96h) (bluegill sunfish).

Other harmful effects: the substance is harmful to the environment, and attention should be paid to the pollution of air and water.^[17]

preventive measure

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1. The production equipment producing hydrogen sulfide should be as closed as possible, and automatic call the police Device (the concentration of hydrogen sulfide in dangerous places cannot be judged according to the odor, and when the concentration of hydrogen sulfide reaches a certain level, it will cause olfactory paralysis).

2. The waste water, waste gas and waste residue containing hydrogen sulfide shall be purified and discharged after reaching the discharge standard.

3. Enter the sealed container, pit kiln 、 Trench etc. Workplace First, measure the concentration of hydrogen sulfide in the air of the place, take ventilation and detoxification measures, and operate after confirming safety.

4. The concentration of hydrogen sulfide in the air of hydrogen sulfide operation environment shall be measured regularly.

5. Take personal protective measures and wear them properly during operation antigas mask The workers are tied with rescue belt or rope at their waist. Mutual protection shall be carried out. More than 2 persons shall be present and the poisoned person shall be rescued immediately in case of abnormal conditions.

6. Suffering from hepatitis 、 nephropathy Personnel with tracheitis shall not be engaged in hydrogen sulfide contact operations.

7. Strengthen the training on professional knowledge of employees and improve their self-protection awareness.

8. Install hydrogen sulfide treatment equipment.^[18]

Industry Considerations

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1. Precautions for sampling operation

(1) Check whether the sampler is intact;

(2) Wear a suitable gas mask, stand upwind and be supervised by a specially assigned person;

(3) The hand valve should be opened slowly during sampling, and should not be knocked with a wrench valve 。

2. Precautions for water cutting operation

(1) Wear a suitable gas mask, be supervised by a specially assigned person, and stand upwind;

(2) There should be a certain distance between the dewatering valve and the dewatering outlet;

(3) Stripped acid gas shall be used calcium hydroxide or sodium hydroxide Neutralize the solution and take isolation measures to prevent passers-by from poisoning;

(4) People shall not leave the site during dehydration to prevent a large amount of acid gas from escaping.

3. Maintenance in equipment

The equipment and container need to be entered for maintenance, which usually goes through purging, replacement and refueling Blind plate Only after the sampling analysis is qualified and the safety work ticket for entering the equipment container is handled can the operation be started. However, before maintenance of some equipment containers, it is necessary to enter people to remove residual oil sludge and residue, and hydrogen sulfide and oil gas will be emitted during the cleaning process Toxic and harmful gases Safety measures must be taken. The following seven items are the steps of maintenance in the equipment:

(1) Prepare construction scheme;

(2) Operators have received safety technical training;

(3) Wear suitable antigas mask , take the safety belt (rope);

(4) Sampling and analysis must be done before entering the equipment container for operation;

(5) The operation time should not be too long, generally not more than 30min;

(6) Handle safety work ticket;

(7) The construction process must be supervised by a specially assigned person, and medical personnel should be present when necessary.

4. Operation in sewers (wells) and trenches

(1) Implement safety protection regulations for confined space operation;

(2) Control the dehydration and condensation of various materials into the sewer;

(3) Forced ventilation or natural ventilation shall be adopted to ensure that the oxygen content is greater than 20%;

(4) Wear gas mask;

(5) Take the safety belt (rope);

(6) Handle safety work ticket;

(7) A specially assigned person shall be assigned to supervise the operation underground when entering the sewer and keep close contact with the ground.

5. Oil pool cleaning operation

(1) Before cleaning the sump, the sump oil sewage Clean and replace with high-pressure water;

(2) Sample and analyze, and determine the safety measures of the construction scheme according to the measurement results;

(3) Wear a suitable gas mask under the supervision of a specially assigned person, and carry it when necessary Safety belt (rope);

(4) Handle the work ticket for confined space.

6. Leakage stoppage, disassembly or installation

When plugging, dismantling or installing equipment, containers and pipelines containing hydrogen sulfide materials, the following must be done:

(1) Strictly control the operation under pressure, close the valve connected with the equipment container, and remove the residual pressure;

(2) Wear a suitable gas mask and have a specially assigned person to monitor;

(3) Disassembly Flange screw Before loosening, do not remove all the screws to prevent a large amount of toxic gas from rushing out.

7. Precautions for inspection of production device

(1) Stable operation and strict prevention of running, emitting, dripping and leaking;

(2) Fixed hydrogen sulfide alarm is installed in the device;

(3) Strengthen the maintenance management of pump equipment to reduce leak ；

(4) Strengthen ventilation in places with leakage;

(5) Containers, pipelines and valves containing hydrogen sulfide materials shall be regularly inspected and replaced;

(6) In case of high concentration of hydrogen sulfide, report it first and take certain protective measures before entering the site for inspection and treatment.

8. Inspection of oil tank

(1) It is strictly prohibited to conduct manual ruler inspection, temperature measurement, disassembly and assembly of safety accessories and other operations during oil inlet, outlet and blending;

(2) For necessary inspection and dehydration, the operator shall stand upwind and be supervised by a specially assigned person;

(3) Prepare suitable gas masks for emergencies.^[19-20]

clinical diagnosis

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acute poisoning^[21]

Poisoning symptoms
1. Mild poisoning	The symptoms include photophobia, tearing, eye tingling, foreign body sensation, runny nose, burning sensation of nose and throat, and accompanied by dizziness, headache and fatigue.
2. Moderate poisoning	Immediately appear dizziness, headache, fatigue, nausea, vomiting, unsteady walking, cough, dyspnea, throat itching, chest oppression, confusion, consciousness disorders and other symptoms, with strong eye irritation symptoms, including tears, photophobia, eye tingling.
3. Severe poisoning	It is characterized by dizziness, palpitations, dyspnea, and slowness of action, followed by irritability, confusion, vomiting, diarrhea, abdominal pain, and convulsions, and quickly enters into a coma state, accompanied by pulmonary edema and brain edema, which may eventually lead to death due to respiratory paralysis.
4. Extremely serious poisoning	After 1~2 mouthfuls of inhalation, the patient suddenly falls to the ground and stops breathing instantly, which means "shock like" death (sudden death).

1. Central nervous system damage is the most common:

(1) Headache, dizziness, fatigue Ataxia , mild Consciousness obstacle 。 Eye and upper respiratory tract irritation symptoms often appear first.

(2) After exposure to high concentrations of hydrogen sulfide, the symptoms of encephalopathy are obvious, headache, dizziness, excitability, gait faltering, irritability, confusion, delirium, epileptic convulsions, and generalized tonic clonic seizures; Coma may occur suddenly; Dyspnea or cardiac arrest after respiratory arrest may also occur. Fundus examination showed that some cases had papilloedema. Some cases may be accompanied by pulmonary edema.

Symptoms of encephalopathy often appear earlier than respiratory symptoms. It may take some time for mucosal irritation to occur.

(3) Shock like death may occur after exposure to extremely high concentrations of hydrogen sulfide, that is, respiratory arrest may occur within seconds or minutes after exposure, and cardiac arrest may occur several minutes later; It can also become unconscious immediately or within a few minutes, and stop breathing and die. Death can occur without vigilance. When the smell of hydrogen sulfide is detected, the sense of smell can be lost immediately. In a few cases, the disgusting sweet smell can be smelled immediately before coma. Before death, there are generally no premonitory symptoms, but deep and fast breathing may occur first, followed by respiratory arrest.

In case of acute poisoning, coma often occurs at the accident site, and the degree varies with the concentration and time of exposure to hydrogen sulfide, occasionally with or without respiratory failure. Some cases can be recovered after leaving the scene of the accident or on the way to the hospital. Patients who still maintain vital signs when arriving at the hospital, if there is no hypoxic encephalopathy, will recover quickly. Those who have been in coma for a long time may have headache, dizziness, vision or hearing loss Disorientation , ataxia or epileptic convulsions, most cases can be completely recovered. It has been reported that 2 cases of delayed encephalopathy occurred, which were resuscitated after 2 days of deep coma, resuscitated after 1.5 days and 3 days respectively, and resuscitated after 2 weeks and 1 month respectively.

The symptoms of central nervous system are very serious, but the symptoms of mucous membrane irritation are not obvious, which may not occur due to short contact time; Or it is easy to cause attention due to serious systemic symptoms.

In the early stage of acute poisoning or those with only brain dysfunction but no morphological changes, electroencephalogram and brain anatomical structure imaging such as computerized tomography (CT) and Magnetic resonance imaging (MRI) is less sensitive, while SPECT/PET abnormalities and clinical manifestations Neuroelectrophysiology The relevance of the inspection is good. If one case was in decortical state after deep coma due to poisoning, CT showed that the density of bilateral globus pallidus was reduced. There was no abnormality in CT and MRI of the head of another patient with poisoning coma; Three years after the accident, PET showed abnormal metabolism in bilateral temporal lobe, inferior parietal lobe, left thalamus and striatum; Half a year later, SPECT showed that bilateral lenticular nucleus flow decreased, and there was no abnormality in cerebral cortex. The patients had anosmia, extrapyramidal signs, memory defects and other manifestations.

Fifteen cases of repeated acute hydrogen sulfide poisoning were reported abroad with fatigue, lethargy, headache, excitement, anxiety, memory loss and other symptoms.

2. Respiratory system damage: chemical bronchitis, pneumonia, pulmonary edema, acute respiratory distress syndrome, etc. may occur. A few cases of poisoning can be characterized by pulmonary edema, while the neurological symptoms are mild. It may be accompanied by conjunctivitis. Keratitis.

3. Myocardial damage: In the course of poisoning, some cases may have palpitations, shortness of breath, chest tightness or angina like symptoms; In a few cases, myocardial infarction like manifestations occurred one week after the recovery of coma and improvement of poisoning symptoms. The ECG showed an acute myocardial dead figure, but it could disappear quickly. Its condition is mild, the course of disease is short, and the prognosis is good. The method of diagnosis and treatment is different from that of myocardial infarction caused by coronary atherosclerotic heart disease, so it is considered as diffuse toxic myocardial damage. Myocardial zymogram examination may be abnormal to varying degrees.

Main basis for diagnosis of acute hydrogen sulfide poisoning:

1. The clothes and breath of patients with a clear history of exposure to hydrogen sulfide can be used as exposure indicators. Hydrogen sulfide can be generated or measured at the accident site. It can be used as a reference for patients to smell rotten eggs before onset.

2. Clinical characteristics: the above clinical manifestations of brain and (or) respiratory system damage.

3. Laboratory inspection: there is no specific laboratory inspection index.

(1) The increase of hydrogen sulfide or sulfide content in the blood can be used as an absorption indicator, but it is inconsistent with the severity of poisoning, and its half reduction period is short, so it is necessary to take blood within a short time after stopping the contact.

(2) The content of thiosulfate in urine can be increased, but it can be interfered by such factors as determination time and sulfur content in diet.

(3) In blood Thiohemoglobin (SHb) cannot be used as a diagnostic indicator, because hydrogen sulfide does not combine with normal hemoglobin to form thiohemoglobin, which is irrelevant to the poisoning mechanism; Many studies have shown that there is no significant concentration of thiohemoglobin in the blood of people and animals killed by hydrogen sulfide.

(4) The sulfur content in the blood and tissue of the corpse can be interfered by factors such as corpse decay, which affects its reference value.

4. Differential diagnosis: electric shock like death at the accident site should be combined with other chemicals such as carbon monoxide Or cyanide and other acute poisoning Acute cerebrovascular disease Myocardial infarction should also be identified from asphyxia caused by entering an environment with high concentration of methane or nitrogen and other chemicals that cause air hypoxia. Other symptoms should also be similar to those caused by similar diseases or falls after coma trauma Phase identification.

Chronic poisoning:

Long term exposure to low concentration H two S can cause chronic inflammation of eyes and respiratory tract, and even Corneal erosion Or punctate keratitis. Systemic neurosis, central autonomic nervous dysfunction and damage may occur peripheral nerve 。^[2]

Poisoning treatment

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First aid measures:

one
Quickly remove the patient from the scene, take off the contaminated clothes, and immediately carry out the treatment for those with respiratory and cardiac arrest Extrathoracic cardiac compression And artificial respiration (mouth to mouth artificial respiration is prohibited, and several layers of wet gauze should be separated from the patient as a last resort).
two
Inhale oxygen as soon as possible, and treat with hyperbaric oxygen as soon as possible if conditions permit. Anyone who is unconscious should be sent immediately Hyperbaric oxygen chamber treatment. The hyperbaric oxygen pressure is 2~2.5 atmospheric pressure; Intermittent oxygen inhalation for 2~3 times, 30~40min each time, and 10 min rest between two times of oxygen inhalation; 1-2 times a day, 10-20 times a course. Generally, 1~2 courses are used.
three
prevention and cure pulmonary edema and Cerebral edema 。 Suitable for early, sufficient and short-term application Glucocorticoid To prevent pulmonary edema and brain edema, available dexamethasone 10mg of glucose solution was added for intravenous drip once a day. When treating pulmonary edema and brain edema, the dose of dexamethasone can be increased to 40~80mg, and glucose solution is added for intravenous drip once a day.
four
Blood exchange therapy. Exchange transfusion therapy can reduce the inactive Cytochrome oxidase And various enzymes and free hydrogen sulfide are cleared out, and then fresh blood is added. It can be used for critically ill patients, and the blood exchange volume is generally about 800mL.
five
Eye irritation treatment. Use first tap water or normal saline Rinse eyes thoroughly, and apply erythromycin eye ointment and Chloramphenicol eye drops , once every 2h, to prevent and control infection, and to drip locally cod-liver oil To promote epithelial growth and prevent conjunctival adhesion.^[21-22]

Hydrogen sulfide poisoning

Environmental hazard control

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On site treatment

Quickly evacuate the personnel in the leakage contaminated area to Upwind And immediately isolate it, 150 m for small leakage and 300 m for large leakage, and strictly restrict access. Cut off the ignition source. It is recommended that emergency personnel wear self-contained positive pressure respirators and anti poison clothing. Enter the site from the upwind. Cut off the leakage source as much as possible. Reasonable ventilation to accelerate diffusion. Dilute and dissolve with spray water. Build a dike or dig a pit to collect a large amount of wastewater generated. If possible, the residual gas or leaked gas shall be sent to the water washing tower or the fume hood connected to the tower with an exhaust fan. Or make it pass Ferric trichloride For water solution, install a check device in the pipeline to prevent the solution from being sucked back. Leaking containers shall be properly treated, repaired and inspected before reuse.

Fire fighting measures

Hazard characteristics: flammable, can form when mixed with air Explosive mixture , can cause combustion and explosion in case of open fire and high heat. And concentrated nitric acid Fuming nitric acid Or other strong oxidants react violently, causing explosion. The gas is heavier than air, and can spread to a considerable distance at a lower place. It will ignite and recoil when encountering an ignition source.

Hazardous combustion products: sulfur dioxide 。

Extinguishing method: firefighters must wear full body fire and gas protective clothing and extinguish the fire upwind. Cut off the air supply. If the air source cannot be cut off, it is not allowed to extinguish the flame at the leakage. Spray water to cool the container, and move the container from the fire site to an open place if possible.

Extinguishing agent: Foggy water , foam carbon dioxide , dry powder.

Protective measures

Hydrogen sulfide gas half mask

Respiratory system protection: wear when the concentration in the air exceeds the standard Filter gas mask (Half mask). Recommended for emergency rescue or evacuation Oxygen respirator or Air respirator 。

Eye protection: wear chemical Safety goggles 。

Body protection: wear Antistatic clothing 。

Hand protection: wear chemical resistant gloves.

Others: Smoking, eating and drinking are strictly prohibited at the work site. After work, take a shower and change clothes. Change and wash work clothes in time. Operators shall learn to save themselves and each other. When entering tanks, confined spaces or other high concentration areas for operation, someone must supervise.

Waste disposal

Disposal by incineration. Incinerator discharge Sulfur oxide adopt Scrubber except.

security management

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Environmental standards

Maximum allowable concentration

The maximum allowable concentration of harmful substances in the air of workshops in China (TJ36-79): 10mg/m ³。

The maximum allowable concentration of harmful substances in the atmosphere of residential areas in China (TJ36-79): 0.0110mg/m ³ (primary value).

China (GB14554-93) Plant boundary standard for odor pollutants (mg/m) ³）： Level I 0.03; Level II 0.06-0.10; Class III 0.32~0.60.

China (GB14554-93) Emission Standard of Odor Pollutants: 0.33 ～ 21kg/h.

Industry exposure limit

NIOSHREL：10ppm（15mg/m ³） 10min peak limit.^[2]

OSHA REL: 20ppm peak limit.^[2]

ACGIH TLV：10ppm（14mg/m ³） TWA； 15ppm（21mg/m ³） STEL。^[2]

NIOSHIDLH value: 100ppm.^[2]

China: PC-MAC 10mg/m ³。^[2]

Monitoring methods

Silver nitrate colorimetry^[3] 。

Gas chromatography (Air)^[4] 。

Iodometry (Natural gas)^[5] 。

Methylene blue method (natural gas)^[6] 。

Double light path detection method for lead acetate reaction rate (natural gas)^[7] 。

Colored length detection tube (air)^[8] 。

On site emergency monitoring method

portable Gas detection instrument : Hydrogen sulfide coulometric detector, hydrogen sulfide gas sensing electrode detector.

Common rapid chemical analysis methods: lead acetate detection tube method, lead acetate indicator paper method^[9] 。

Gas quick measuring tube.

Operational disposal

It shall be tightly sealed to provide adequate local ventilation and overall ventilation. Operators must be specially trained and strictly abide by the operating procedures. It is recommended that operators wear filter type gas mask (half mask), chemical safety goggles, anti-static work clothes and chemical gloves. Keep away from kindling and heat sources, and smoking is strictly prohibited in the workplace. Use explosion-proof ventilation systems and equipment. Prevent gas leakage into the air of the workplace. Avoid contact with oxidants and alkalis. During transmission, the cylinder and container must be grounded and bridged to prevent static electricity. The cylinder and accessories shall be handled with care to prevent damage. Fire fighting equipment and leakage emergency treatment equipment of corresponding types and quantities shall be provided.

Storage and transportation method

Precautions for storage: store in a cool and ventilated warehouse. Keep away from kindling and heat sources. The warehouse temperature should not exceed 30 ℃. Keep container sealed. Should be connected with Oxidant Alkalis shall be stored separately, and mixed storage shall be avoided. Explosion proof lighting and ventilation facilities shall be adopted. It is prohibited to use mechanical equipment and tools that are easy to generate sparks. The storage area shall be equipped with leakage emergency treatment equipment.

Precautions for packaging: steel gas cylinder; Ordinary wooden case outside frosted glass bottle or threaded glass bottle; Ordinary wooden case outside the ampoule bottle.

Precautions for transportation: during railway transportation, the dangerous goods shall be loaded in strict accordance with the dangerous goods loading table in the Dangerous Goods Transportation Rules of the Ministry of Railways. The safety helmet on the cylinder must be worn when the cylinder is used for transportation. Cylinders are generally placed horizontally, and the mouth of the cylinder should be in the same direction, not crossed; The height shall not exceed the protective fence of the vehicle, and shall be firmly clamped with triangular wood pad to prevent rolling. The transport vehicles shall be equipped with corresponding types and quantities of fire-fighting equipment. The exhaust pipe of the vehicle transporting this article must be equipped with a fire retardant device. It is prohibited to use mechanical equipment and tools that are easy to generate sparks for loading and unloading. It is strictly prohibited to mix with oxidants, alkalis, edible chemicals, etc. Transport in the morning and evening in summer to prevent sunlight exposure. Keep away from kindling and heat sources during stopover. Road transportation shall be carried out according to the specified route. It is forbidden to stay in residential areas and densely populated areas, and it is forbidden to slip away during railway transportation.

Hazardous area

Access to the following areas must be approved by the workshop, accompanied by a supervisor, and equipped with positive pressure Self contained air respirator , use portable Hydrogen sulfide detection alarm 。

Extremely hazardous area	The maximum allowable concentration of hydrogen sulfide in air is 10mg/m ³。 When the concentration ≥ 760mg/m ³ (502ppm), people will soon suffer from acute poisoning, respiratory paralysis and death. This area is an extremely dangerous area, and may appear near the following devices: sulfur recovery unit, sewage stripping unit, flare unit, areas along the acid gas pipeline, gas and gas desulfurization flare tanks, and the first and second gas desulfurization parts.
Highly hazardous area	When the concentration of hydrogen sulfide is between 300 and 760mg/m ³ (198-502ppm) may cause pulmonary edema, bronchitis and pneumonia, headache, dizziness, nausea, vomiting and dysuria. This area is a highly dangerous area, which may appear near the following units: the sheared water from distillation unit, normal overhead and overhead reduction, the sheared water from light hydrocarbon recovery reflux drum, the sheared liquid from desulfurization drum, and the acidic water from light hydrocarbon recovery debutanizer overhead, Light hydrocarbon recovery Unit dry gas pipeline, area along flare line, gas tank, gas pipe network, catalytic and hydrogenation acid water tank, catalytic fractionation part, stabilization part, desulfurization part, compressor, 641, 642 waste steam tank, etc.
Moderately hazardous area	When the concentration of hydrogen sulfide is 10mg/m ³～ 300mg/m ³ (6.6~198ppm), acute eye irritation may occur, and pulmonary edema may be caused by slightly prolonged contact. This area is moderately hazardous and may occur near the following devices: Liquid sulfur storage and forming unit of sulfur complex, sewage plant, electric desalting and shearing water of distillation unit, sewage pool.

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security information

Dangerous transport code

UN 1053 2.3

Dangerous goods sign

inflammable

2.1 (Flammable gas)

Extremely toxic

2.3 (Toxic gas)

Harmful to the environment

9.7 (Harmful to the environment)

Safety instructions

S9: Keep the container in a well ventilated place.

S16: Keep away from fire sources.

S36: Wear appropriate protective clothing.

S38: Wear proper breathing apparatus in places with poor ventilation.

S45: In case of accident or discomfort, go to the doctor immediately for help (it is better to bring the product container label).

S61: Avoid discharging into the environment. Refer to special instructions/safety data sheets.

Hazard Category Code

R12: Extremely flammable.

R26: Very toxic by inhalation.

R16: Explosion occurs when mixed with oxidizing substances.

R50: Very toxic to aquatic organisms.

Natural origin

1. Biodegradation

It is the process of forming hydrogen sulfide under the leading role of corruption. Corruption is caused by sulfur Organic matter After formation, when the assimilation environment changes, the organic matter containing sulfur will decay and decompose, thus releasing hydrogen sulfide. This mode occurs in the early stage of coalification, and the scale and content of generated hydrogen sulfide are not large, and it is difficult to gather.

2. Microbial sulfate reduction

Microbial sulfate reducing bacteria utilize various organic matter or Hydrocarbons come Reduced sulfur Acid salt directly forms hydrogen sulfide under dissimilation. In this process, sulfate reducing bacteria only combine a small part of the metabolized sulfur into cells, and most of the sulfur is absorbed by aerobic organisms to complete the energy metabolism process. The decomposition products of organic matter of some strains may become the nutrients that other strains need to absorb, which will improve the absorption and transformation efficiency of organic matter by sulfate reducing bacteria, thus producing a large amount of hydrogen sulfide. This way of sulfate reducing bacteria reducing sulfate to generate hydrogen sulfide is also called microbial sulfate reduction (BSR).

This process is the main type of action of the biochemical origin of hydrogen sulfide. Since this dissimilatory reduction is carried out in a strict anaerobic environment, it is conducive to the preservation and accumulation of the generated hydrogen sulfide, but the abundance of the generated hydrogen sulfide generally does not exceed 2%, and the formation media conditions must be appropriate Sulfate reducing bacteria It is difficult to grow and reproduce in deep layers.

3. Thermochemical decomposition

It refers to the formation of hydrogen sulfide from the sulfur heterocyclic fracture of sulfur containing organic compounds in coal under the thermal action, which is also called pyrolysis hydrogen sulfide. The concentration of hydrogen sulfide formed in this way is generally less than 1%. The thermochemical reduction of sulfate mainly refers to the reaction between sulfate and organic matter or hydrocarbon, which reduces sulfate minerals to H two S and CO two 。

4. Thermochemical sulfate reduction

It is the main form of generating high hydrogen sulfide containing natural gas and hydrogen sulfide type natural gas, and its temperature is generally higher than 150 ℃.

Thermochemical decomposition of sulfur containing organic matter and sulfate rock in coal and surrounding rock（ splitting ）Action and thermochemical reduction can generate H two S gas. Due to the low content of organic matter sulfur and sulfate sulfur in coal and surrounding rock two The content of S generally does not exceed 2%. If the content of sulfate rock in surrounding rock is high, more H can be produced two S gas.

4. Magmatism

Because the abundance of sulfur element in the earth's interior is much higher than Crust , magmatic activity makes rocks in deep crust melt And produce volatile matter containing hydrogen sulfide, so magma often contains hydrogen sulfide. The content of hydrogen sulfide mainly depends on the composition of magma, gas migration conditions, etc. Therefore, the content of hydrogen sulfide in magma is extremely unstable, and only under specific migration and reservoir conditions can the content of hydrogen sulfide in coal seam Gather together in.

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