[Research methods] Searching for information, surfing the Internet, investigation and experiment.
[Research Steps] 1. Bring up topics of interest.
2, clear goals, make plans.
3, access to information, experiment.
4. Complete the thesis and presentation.
5, the results show that the defense
[Team members] Tong Longhuan, Chen, Tan, Hu Wei, Xie Gang, Liu Shengqi, Liu and Feng Xiujun.
[Instructor] Duan went to the hills.
Abstract: With the development of economy, the role of dry batteries in our life is becoming more and more important, and the usage is also increasing rapidly, reaching almost every corner of our life. However, these used waste dry batteries have not been properly disposed of. Although the volume and mass of waste dry battery are very small, it is insignificant in domestic garbage, but it contains a variety of metal substances. If it is not handled properly, it will pollute water, soil, air, etc., which will directly or indirectly endanger people's health and affect people's normal life. It can be seen that the harm of waste dry batteries is indeed not small.
[Keywords:] waste dry batteries, heavy metal hazards, pollution recovery, environmental protection
First, the research purpose
"Garbage besieged city" sounded the alarm for us. We hope that through the research of the subject, people will know more about the harm and recycling of waste dry batteries. Protecting the environment is everyone's responsibility. I hope everyone will pay attention to the recycling of waste dry batteries and study more treatment methods to turn harm into benefit. We know that individual strength may be insignificant, but it is enough to prop up a civilization, a civilization with sustainable development, and build an environmentally-friendly "Great Green Wall" by uniting the strength of everyone.
Second, the introduction of waste dry batteries.
1. Structure and composition of dry battery: Our commonly used dry battery is called zinc-manganese battery, also called carbon-zinc battery. Its cathode is a cylinder made of zinc, which is made into a cylinder and used to store chemicals such as electrolyte. The anode is a carbon rod, which is wrapped by a mixture of manganese dioxide, carbon powder and ammonium chloride, and is called a carbon package. Paste composed of ammonium chloride, zinc chloride aqueous solution and starch is filled between the carbon bag and the zinc tube, which is called electric paste. The battery mouth is sealed with sealant made of asphalt and rosin. When the dry cell works, zinc reacts with ammonium chloride to produce hydrogen, which is attached to the carbon rod. Due to the high resistance of hydrogen, the battery will have "polarization phenomenon" when working, which will generate considerable voltage near the battery and reduce the terminal voltage of the circuit. Therefore, manganese dioxide is added to the battery as a "depolarizer", and carbon powder is added to conduct electricity and absorb some gases produced in the reaction process. The main component of the paste is ammonium chloride, which is equivalent to the dilute sulfuric acid of voltaic cells. The function of zinc chloride in zinc paste is to increase the concentration of zinc ions in solution, reduce the corrosion of zinc tubes by ammonium chloride and prolong the service life of batteries. Ingredients: zinc-containing skin (iron sheet), carbon rod, mercury, sulfuric acid compound, copper cap, etc. For example, 1 waste zinc-manganese battery weighs about 70g, including 5.2g carbon rod, 7.0g zinc skin, 25g manganese powder, 0.5g copper cap and 32g others.
2. Production and consumption of batteries in China: China is a big producer and consumer of primary dry batteries. /kloc-0 produced1500 million batteries in 1999,1630 million batteries in 2000 and1740 million batteries in 5438+0 years in 2006, increasing year by year. According to the statistics of relevant departments, China consumes 8 billion dry batteries every year, and it is increasing at the rate of 10%. The above does not include nickel-cadmium batteries, nickel-hydrogen batteries, lithium-ion batteries, lead-acid batteries and other secondary batteries. Therefore, China produces a large number of waste batteries every year.
Third, the harm of waste dry batteries
1, the harmfulness of waste batteries
A grain of button cell can pollute 600,000 liters of water, which is equivalent to a person's lifetime drinking water. A piece of rotten battery in the field can make one square meter of land lose its use value, so it is no exaggeration to say that waste batteries are "small pollution bombs" Dry batteries commonly used in our daily life mainly include acidic zinc-manganese batteries and alkaline zinc-manganese batteries, both of which contain many heavy metal elements such as mercury, manganese, cadmium, lead and zinc. After the waste dry batteries are abandoned, the shell of the batteries will slowly corrode, and the heavy metals in them will gradually penetrate into the water and soil, causing pollution. The biggest feature of heavy metal pollution is that it cannot be degraded in nature and can only be eliminated by artificial purification. At the same time, because heavy metals are easy to accumulate in organisms, they will cause teratogenesis or carcinogenesis after reaching a certain amount over time, which will eventually lead to biological death. Another way that heavy metals do harm to human body is to spread through food chain. After fish and shrimp eat plankton containing heavy metals, heavy metals accumulate in fish and shrimp. After people eat such fish and shrimp again, heavy metals will accumulate in the human body, which will have a serious impact on people's health after reaching a certain level. The harm of waste batteries mainly focuses on a small amount of heavy metals contained in them.
Cadmium: Accumulated from respiratory tract and digestive tract. Chronic poisoning leads to emphysema, anemia and bone changes, while acute poisoning easily leads to general paralysis.
Manganese: excessive accumulation of manganese in the body causes neurological dysfunction, which is manifested as comprehensive sexual dysfunction in the early stage. The heavier ones have heavy legs, monotonous language, dull expression and indifference, often accompanied by mental symptoms.
Zinc: Zinc salt can precipitate protein, which is irritating to skin and mucous membrane. When the concentration in water exceeds 10-50 mg/L, there is a risk of cancer, which may cause chemical pneumonia.
Lead: Lead mainly acts on nervous system, blood circulation system, digestive system, liver, kidney and other organs, which can inhibit the anabolic process of hemoglobin, and can also directly act on mature red blood cells, which has a great influence on infants. It will lead to physical retardation of children, and chronic lead poisoning will lead to mental retardation of children.
Nickel: Nickel powder is soluble in blood, participates in internal circulation, and has strong toxicity, which can damage the central nervous system, cause vascular variation, and even lead to cancer in severe cases.
Chromium: It can cause digestive dysfunction, lung cancer and gastrointestinal ulcer.
Mercury: It is the most noteworthy of these heavy metal pollutants. This heavy metal is very harmful to human beings. According to our investigation, for a long time, in the production of dry batteries in China, a toxic substance-mercury or mercury compounds has been added. In China, the mercury content of alkaline dry batteries reaches 1-5%, and that of neutral dry batteries is 0.025%. Mercury used in the production of dry batteries in China has obvious neurotoxicity and adverse effects on endocrine system and immune system. From 65438 to 0953, Minamata disease occurred in Kyushu Island, Japan, which shocked the world and sounded the alarm for mercury pollution.
Ways: battery → soil → microorganism → plant → animal → food → human body → nerve → chronic disease.
Heavy metals such as mercury, cadmium, lead, zinc and chromium will denature protein and threaten human health. If human beings ignore the control of heavy metal pollution, they will eventually swallow the bitter fruit of self-brewing. Therefore, it is more and more important to strengthen the recycling of waste dry batteries.
2. Other manifestations of the hazards of waste dry batteries
At present, there are four main ways to treat domestic garbage in the world: sanitary landfill, incineration, composting and reuse. The pollution of waste dry batteries mixed with domestic garbage in these four processes is reflected in:
Landfill: Heavy metals in waste batteries pollute water and soil through osmosis.
Incineration: waste batteries corrode equipment at high temperature, and some heavy metals volatilize in the fly ash of incinerator, causing air pollution; Heavy metals accumulate at the bottom of the incinerator, polluting the ash.
Composting: The high content of heavy metals in waste batteries leads to the decline of compost quality. In addition, batteries may interact with each other to accelerate the melting of heavy metals, and the pollution will increase accordingly.
Reuse: reverberatory furnace metallurgy is generally used. Although the process is easy to master, the recovery rate is only 82%, and the rest lead appears in the form of gas and dust. At the same time, sulfur dioxide in the smelting process will enter the air, causing secondary pollution and directly endangering the health of operators.
3. Understand the harm of waste dry batteries by doing experiments.
Purpose of the activity: arrange some experiments to let students know the influence of waste dry battery pollutants on animals and plants, and let students learn to cooperate with others, design experiments and make observation records. By looking for information, we can further understand the harm of waste dry batteries.
Experiment 1: Effects of pollutants from waste dry batteries on plant growth
Experimental tools: two containers.
Experimental materials: four garlic, two batteries and some mineral water.
Experimental steps:
1. Dissect the battery, dissolve its internal substances in mineral water, and make 2L solution.
2. Soak garlic in clear water and battery liquid containers respectively, and observe the changes of garlic.
Experimental data and pictures:
(1) Just joined:
Figure 1: Garlic in clean water has not changed Figure 2: Garlic in battery solution has not changed.
② 6 hours after adding battery liquid:
Figure 3: Garlic does not change in clear water Figure 4: Garlic is a little discolored.
③ On the 3rd day of adding battery liquid:
The garlic in the battery solution is a little wilted, and the garlic in the clear water has not changed.
④ On the 5th day of adding battery liquid:
There are pits on the surface of garlic in battery solution, but garlic is still fresh in clean water.
⑤ On the 7th day of adding battery liquid:
The pits on the surface of garlic in battery solution became larger, but there was no obvious change in garlic in clean water.
⑥ Add battery liquid on day 10:
The surface of garlic in the battery solution is black, the top is obviously yellow, and the roots are all black. But garlic has no obvious change in clean water.
Experiment 2: Effects of pollutants from waste dry batteries on the growth of aquatic animals
Experimental tools: three fish tanks.
Experimental materials: two goldfish, some mixed liquid and six bottles of mineral water.
Experimental steps: firstly, add appropriate mineral water into two fish tanks, and put two goldfish with the same appearance and size into two containers respectively; Then pour the battery waste liquid into a fish tank, take out the goldfish after 5 minutes, and put it into another fish tank filled with clear water to observe the phenomenon; Then, replay it back to the original cylinder for observation.
Experimental data and pictures:
(1) Early stage:
Photo 1: Goldfish with the same shape and size swim freely in clear water.
⑵ Mid-term: The goldfish did not change in clear water, but the goldfish soaked in battery solution for 5 minutes was in poor swimming condition.
⑶ Later stage: Focus on observing the changes of goldfish in battery solution.
① 4th hour after adding battery liquid: the degree of live wave of goldfish with battery liquid container decreased obviously; Goldfish has not changed in clear water.
The potential pollution of waste batteries has attracted wide attention from all walks of life. China is the largest producer and consumer of dry batteries in the world. According to the data, there are more than 1400 battery manufacturers in China, and the dry battery output of 1980 has surpassed that of the United States, ranking first in the world. From 65438 to 0998, the output of dry batteries in China reached1400 million, while the total output of dry batteries in the world in the same year was about 30 billion. The potential pollution of waste batteries has attracted wide attention from all walks of life. China is the largest producer and consumer of dry batteries in the world. According to the data, there are more than 1400 battery manufacturers in China, and the dry battery output of 1980 has surpassed that of the United States, ranking first in the world. From 65438 to 0998, the output of dry batteries in China reached1400 million, while the total output of dry batteries in the world in the same year was about 30 billion.
Such a huge number of batteries exposes a big problem, that is, how to make so many batteries not destroy and pollute our living environment. According to our investigation, waste batteries contain a lot of heavy metals and electrolyte solutions such as waste acid and waste alkali. If discarded at will, corrupt batteries will destroy our water source, erode the crops and land on which we depend, and our living environment is facing great threats. If a 1 battery rot in the ground, its toxic substances can make one square meter of land lose its use value; Throw a grain of button cell into the water, which contains toxic substances that will pollute 600,000 liters of water; Waste batteries contain heavy metals such as cadmium, lead, mercury, nickel, zinc and manganese, among which cadmium, lead and mercury are harmful to human body. However, although metals such as nickel and zinc are beneficial substances in a certain concentration range, exceeding the limit in the environment will also cause harm to the human body. Heavy metals oozing from waste batteries will pollute rivers, lakes, oceans and other water bodies, endanger the survival of aquatic organisms and the utilization of water resources, and indirectly threaten human health. Waste acid, waste alkali and other electrolyte solutions may pollute the land, acidifying and salinizing the land, just like a time bomb buried around us. Therefore, the collection and disposal of waste batteries is very important. If it is not handled properly, it may cause serious harm to the ecological environment and human health. Discarding waste batteries at will not only pollutes the environment, but also wastes resources. Someone has calculated an account. Based on the annual production of 654.38+000 billion batteries in China, the annual consumption is 654.38+056 million tons of zinc, 226,000 tons of manganese dioxide, 2080 tons of copper, 27,000 tons of zinc chloride, 79,000 tons of ammonium chloride and 43,000 tons of carbon rods.
Toxicity of mercury
Mercury, commonly known as "mercury", is a liquid substance at room temperature, which can prevent the oxidation of cathode metal zinc in the battery and improve the storage life of the battery. So as early as before, almost all batteries with zinc as the negative electrode had a certain amount of mercury as a preservative. However, the combination of mercury and mercury is neurotoxic and has adverse effects on endocrine system and immune system. It will lead to slurred speech, unsteady gait, quadriplegia, and finally lead to general spasm and mental disorder and death.
With the progress of science and technology, the battery began to gradually implement low mercury and mercury-free, and the fluoropolymer Forafac, which replaced mercury, achieved good results in preventing zinc corrosion.
For a long time, when producing dry batteries in China, a toxic substance-mercury or mercury compounds has to be added. Cadmium toxicity of alkaline dry batteries in China
Cadmium is not an essential trace element for human body. There is no cadmium in newborn babies, but it will gradually accumulate with age. Cadmium has nephrotoxicity, and the damage of cadmium to kidney is irreversible. At the same time, osteoporosis, chondrosis, fracture and so on can occur after kidney injury. In 1993, the International Union for Cancer Control designated cadmium as a carcinogen of IA. For the above reasons, many developed countries suggested that the use of cadmium-nickel batteries should be banned, and nickel-hydrogen batteries replaced cadmium-nickel batteries, thus avoiding the use of cadmium. However, most battery manufacturers in China still use cadmium as raw material to produce batteries, which further increases the harm of batteries.
Although the waste battery is small, it is very harmful. However, because the pollution of waste batteries can not be felt by the senses like garbage, air and water pollution, it has great concealment, so it has not been paid due attention. At present, China has become a big country in battery production and consumption, and waste battery pollution is a major environmental problem that needs to be solved urgently.
Although advanced technology has given us the right direction, the battery pollution situation in China is still not optimistic. At present, most of the waste batteries in China are mixed with domestic garbage and buried underground. As time goes by, after conversion, the battery will rot and heavy metals will dissolve, which may pollute groundwater and soil. Once crops are planted, heavy metals may accumulate in crops and eventually affect human health through the food chain.