Si Nuo. 7439-92- 1
Chinese name lead
English name Lead lead sheet
anonymous
The appearance and properties of molecular formula Pb are gray soft powder, with shiny section, weak ductility and strong ductility.
Molecular weight 207.2 vapor pressure 0. 13kPa(970℃)
Melting point 327℃ Boiling point: 1620℃ Soluble, insoluble in water, soluble in nitric acid, hot concentrated sulfuric acid, lye, insoluble in dilute hydrochloric acid.
Density The relative density (water =1)11.34 (20℃) is stable.
Danger signs are mainly used for cables, batteries, lead smelting, copper scrap smelting, printing, welding and so on.
2. Impact on the environment
I. Health hazards
Invasion route: inhalation and ingestion.
Health hazards: damage to hematopoiesis, nerves, digestive system and kidneys. Occupational poisoning is mainly chronic. The main manifestations of nervous system are neurasthenia syndrome, peripheral neuropathy (especially motor function), and lead poisoning encephalopathy may occur in severe cases. The digestive system is characterized by gingival lead line, loss of appetite, nausea, abdominal distension, diarrhea or constipation, and moderate to severe abdominal cramps can be seen. Hematopoietic system damage appears porphyrin metabolism disorder, anemia and so on. Acute or subacute lead poisoning can occur after short-term high-dose exposure, which is similar to severe chronic lead poisoning.
Lead is inhaled into the human body in the form of inorganic matter or dust, or invades the human body through the digestive tract through water and food, accumulates in the "repositories" such as bone marrow, liver, kidney, spleen and brain, and then slowly releases into the blood, causing chronic poisoning (acute poisoning is rare). Lead is toxic to the whole body, but especially to the nervous system, blood and cardiovascular system. Alkyl lead compounds are flammable liquids with neurotoxicity and high toxicity. Acute poisoning can cause excitement, muscle tremor, spasm and quadriplegia.
Second, toxicological data and environmental behavior.
Acute toxicity: LD5070mg/kg (intravenous injection in rats)
Subacute toxicity: 10μg/m3. After 30-40 days of exposure, the activity of red blood cell porphobilinogen synthase (ALAD) decreased by 80%-90%, and the blood lead concentration was as high as150-200μ g/100 ml. There are obvious symptoms of poisoning. After inhaling10μ g/m3 ~12 months, the number of macrophages eluted from the lungs decreased by 60%, and various poisoning symptoms appeared. 0.0 1mg/m3, occupational exposure, urinary system inflammation, blood pressure change, death, female fetal death.
Chronic toxicity: Long-term exposure to lead and its compounds can lead to palpitation, lizard excitement and hemogram erythrocytosis. After lead invades the nervous system, insomnia, dreaminess, memory loss and fatigue appear, which further develops into mania, blindness, confusion and coma, and finally dies of cerebral vascular hypoxia.
Carcinogenesis: Animal experiments on inorganic compounds of lead show that it may cause cancer. According to the literature, lead is a chronic cumulative poison, and the sensitivity of different individuals varies greatly. Lead is a potential urinary carcinogen for people.
Teratogenesis: There are not enough animal experiments to provide evidence that lead and its compounds have teratogenic effects.
Mutation: Feeding mice with lead acetate containing 1% increased the number of chromosome breaks in leukocyte culture, involving a single chromosome, indicating that DNA replication was damaged.
Metabolic degradation: inorganic lead and its compounds in the environment are very stable and not easy to be metabolized and degraded. The toxicity of lead to human body is cumulative. 25% of the lead inhaled by the human body is deposited in the lungs, and some of it enters the blood through the dissolution of water. If a person's continuous exposure to lead in the air is 1μg/m3, then the level of lead in human blood is 1 ~ 2 μ g/ 100 ml of blood. About 10% of the lead ingested from food and drinks is absorbed. If you take 10μg of lead from food every day, the lead content in blood is 6 ~ 18μ g/ 100 ml of blood. A small part of these lead compounds can be excreted through the digestive system, mainly through urine (about 76%) and intestine (about 16%), and the rest through various unknown substances.
Residue and accumulation: Lead is an accumulative poison. People can take lead through the food chain and polluted air. The lead content in American lungs is higher than that in Africa, the Near East and the Far East, which is because of the serious lead pollution in American air. From the results of human anatomy, it is proved that 70% ~ 90% of lead invading human body is finally deposited in the form of lead phosphate (PbHPO4) and attached to bone tissue. The lead content in the bones of modern Americans is 100 times higher than that of ancient people. The content of this part of lead gradually increases throughout life, but after the lead accumulated in human soft tissues including blood reaches a certain level (early adulthood), there is almost no change, and the excess part will be excreted by itself (as mentioned above), showing an obvious turnover rate. Fish has a strong enrichment effect on lead.
Migration and transformation: According to the research report of the National Research Council of Ottawa, Canada (1978) on the migration of lead in the world environment, the global average lead concentration in seawater and fresh water is 0.03 μ g/L, the global average lead content in rural air is 0. 1μg/m3, and the lead concentration range in urban air is1~/kloc-. The average background value of lead in soil and rocks in the world is 13mg/kg. The environmental fate of lead in the world soil is: 6.5438+0.5 million tons from air to soil, 250,000 tons from air to sea, and 4.65438+0.6 million tons from soil to sea every year. There are 400,000-600,000 tons of mud transferred from seawater to the seabed every year. Because lead in water, soil and air is absorbed by organisms and transferred to organisms, the average content of lead in various plant foods in the world is 0. 1 ~ 1mg/kg (dry weight), the average content of lead in food is 2.5mg/kg, the average content of lead in fish is 0.2-0.6 mg/kg, and the crustaceans and soft bodies in some coastal polluted areas.
The industrial pollution of lead comes from the waste water and waste produced by mining, smelting, rubber production, dyes, printing, ceramics, lead glass, solder, cables and lead pipes. In addition, tetraethyl lead in automobile exhaust is a highly toxic substance. When the water is polluted by lead (Pb 0.3 ~ 0.5 mg/L), the self-purification ability of the water is obviously inhibited, and when Pb 2 ~ 4 mg/L, the water is turbid.
Danger characteristics: The powder will burn and explode if it is heated, exposed to open fire or contacted with oxidant.
Combustion (decomposition) product: lead oxide.
3. On-site emergency monitoring methods
Determination of harmful substances in the air by tetracarboxylic quinone test paper colorimetry, edited by Hang Shiping.
Rapid measuring instrument method; Spectrophotometry; Emergency monitoring and disposal technology of sudden environmental pollution accident by anodic stripping voltammetry.
4. Laboratory monitoring methods
Source categories of monitoring methods
GB7475-87 water quality atomic absorption spectrometry
Mcso- Tetrakis (p-sulfobenzene) Porphyrin Spectrophotometry WS/T 126- 1999 Workplace Air
Hydride Generation-Atomic Absorption Spectrometry WS/T 127- 1999 Workplace Air
GB/T 15555.2-95 atomic absorption spectrometry of solid waste leachate
Graphite furnace atomic absorption spectrometry GB/T17141-1997 Soil.
Flame atomic absorption spectrometry GB/T17140-1997 Soil
Flame atomic absorption spectrometry GB/T 15264-94 Air quality
Atomic absorption method CJ/T 10 1-99 Municipal Solid Waste
Atomic absorption spectrometry "Manual for Testing, Analysis and Evaluation of Solid Waste" translated by China National Environmental Monitoring Center, etc.
5. Environmental standards
The maximum allowable concentration of harmful substances in the air of China (TJ36-79) workshop is 0.03mg/m3[ lead smoke]; 0.05 mg/m3 [lead dust]
The maximum allowable concentration of harmful substances in the air of China (TJ36-79) residential area is 0.0007mg/m3 (daily average).
China ambient air quality standard (GB3092- 1996) seasonal average:1.50ug/m3; Annual average: 1.00 μ g/m3.
China (GB 16297- 1996) Comprehensive Emission Standard for Air Pollutants (Lead and Its Compounds) ① Maximum allowable emission concentration (mg/m3): 0.90 (table1); 0.70 (Table 2)② Maximum allowable discharge rate (kg/h): Grade II is 0.005 ~ 0.39; 0.007 ~ 0.60 for the third level (table 1) and 0.004 ~ 0.33 for the second level; Grade Ⅲ 0.006 ~ 0.5 1 (Table 2)③ Monitoring concentration limit of unorganized emission: 0.0060mg/m3 (Table 2); 0.0075 mg/m3 (table 1)
The drinking water quality standard in China (GB5749-85) is 0.05 mg/L.
China (GHZB 1- 1999) Class I surface water environmental quality standard (mg/L) 0.01; Class Ⅱ 0.05; Class ⅲ 0.05; Class ⅳ 0.05; ⅴ class 0. 1
China (GB/T 14848-93) groundwater quality standard (mg/L) Class I 0.005; Class Ⅱ 0.01; Class ⅲ 0.05; Class ⅳ 0.1; Ⅴ class > 0. 1
China (GB3097- 1997) seawater quality standard (mg/L) Class I 0.001; Class Ⅱ 0.005; Class ⅲ 0.010; Class Ⅳ 0.050
The water quality standard of farmland irrigation in China (GB5048-92) is 0. 1mg/L (water, dry vegetables).
China (GB 1 1607-89) fishery water quality standard is 0.05 mg/L.
China (GB8978- 1996) Integrated Wastewater Discharge Standard1.0 mg/L/L.
China (GB15618-1995) Soil Environmental Quality Standard (mg/kg) Grade I 35; Technical secondary school 250 ~ 350; Level 3 500
The standard value of leaching toxicity of solid waste in China (GB5058.3- 1996) is 3 mg/L.
China (GWKB3-2000) Pollution Control Standard for Domestic Waste Incineration: Emission limit of air pollutants from incinerators: 1.6mg/m3 (measured average).
China (GB8 172-87) Waste Control Standard for Agricultural Cities 100mg/kg
6. Emergency treatment and disposal methods
First, the emergency treatment of leakage
Cut off the fire. Wear a gas mask and general fire protection clothing. Collect it in a dry, clean and covered container with a clean shovel, solidify it with cement, asphalt or suitable thermoplastic material, and then discard it. Such as a large number of leaks, collected and recycled or discarded after harmless treatment.
① For leaked PbCl4 and Pb(ClO4)2, all protective articles such as gas masks should be worn. Mix it with dry sand, pour it into a large amount of water in small batches, and put the diluted sewage into the wastewater system.
② For leaked PbO, tetramethyl (b) lead and Pb3O4, all protective articles such as gas masks should be worn. Mixed with dry sand, and then dumped in the open space for burial; The polluted ground is scrubbed with soap or detergent, and the diluted sewage is put into the wastewater system.
③ For leaked PbF2, all protective articles such as gas masks should be worn. Sprinkle soda ash on the leak; The polluted ground is washed with water, and the diluted sewage is put into the wastewater system.
④ For leaked Pb(BrO3)2, PbO2 and Pb(NO3)2, all protective articles such as gas masks should be worn. The contaminated noodles are washed with water, and the diluted sewage is put into the wastewater system.
⑤ For leaked alkyl lead, make emulsion with incombustible dispersant for scrubbing. If there is no dispersant, it can be adsorbed by sand and buried in an open place; The polluted ground is scrubbed with soap or detergent, and the diluted sewage is put into the wastewater system.
Treatment method: When the water body is polluted, neutralization method can be adopted, that is, lime milk is added to adjust the pH value to 7.5, so that lead can be precipitated in the form of lead hydroxide and transferred from water to sludge. Mechanical stirring can accelerate clarification, the purification effect can reach 80% ~ 96%, the lead concentration in the treated water is 0.37 ~ 0.40 mg/L, and the sludge is further treated harmlessly. For lead-contaminated soil, amendments such as lime and phosphate fertilizer can be added to reduce the activity of lead in soil and the absorption of lead by crops.
Second, the protective measures
Respiratory protection: Workers should wear dust masks.
Eye protection: You can use a safety mask if necessary.
Protective clothing: wear work clothes.
Hand protection: Wear protective gloves if necessary.
Others: Smoking and eating are prohibited in the workplace. Take a shower and change clothes after work. Carry out pre-job and regular physical examination. Maintain good hygiene habits.
Third, first aid measures.
Skin contact: Take off contaminated clothes and rinse thoroughly with soapy water and flowing clean water.
Eye contact: immediately open the upper and lower eyelids and rinse with running water or normal saline. See a doctor.
Inhalation: leave the scene quickly and go to a place with fresh air. Keep the respiratory tract unobstructed. Oxygen is given when breathing is difficult. When breathing stops, give artificial respiration immediately. See a doctor.
Ingestion: Drink plenty of warm water, induce vomiting and seek medical advice.
Fire extinguishing method: dry powder and sand.