White pollution is a unique environmental pollution in China. A large number of discarded plastic products can be seen everywhere in various public places. They come from nature and are made by humans. When they finally belong to nature, they are not easily absorbed by nature, thus affecting the ecological environment of nature. From the perspective of resource conservation, since the main source of plastic products is exhausted oil resources, it should be recycled as much as possible. However, because the production cost of recycling at this stage is much higher than the direct production cost, it is difficult to do so under the current market economy conditions. Faced with the increasingly serious problem of white pollution, people hope to find a plastic substitute, which can not only replace the performance of existing plastics, but also cause no white pollution, and degradable plastics emerge as the times require. The characteristic of this new functional plastic is that its chemical structure will change obviously under certain environmental conditions after reaching a certain service life. For example, starch-filled plastics are rapidly decomposed by amylase secreted by microorganisms in the soil in a short time, which leads to the decline of mechanical properties of the film. At the same time, the self-oxidant added in the formula reacts with the metal salt in the soil to generate peroxide, which breaks the chain of polyethylene and degrades it into small fragments that are easily swallowed by microorganisms, which can be absorbed by the natural environment and improve the soil.

The earth is our home, and this home is surrounded by garbage. As the masters of the 2 1 century, we should not just worry and complain, but take action and take green action. Garbage is not useless, nor is waste. Recycling garbage is not difficult in technology. The difficulty is that if you throw it away and mix it together, the waste will become garbage. Therefore, as educated and civilized people in the new century, we should participate in the "readily available" garbage source classification activities, contribute to purifying our living space, and offer a love.

Domestic garbage is a by-product of human life. With the rapid development of social economy and the high concentration of urban population, the output of domestic waste is increasing gradually. Generally speaking, domestic waste can be divided into five categories: waste paper, plastic, glass, metal and biological waste. The main hazards of garbage to human life and environment are:

First, it occupies too much land. Garbage piled up in the suburbs of the city occupies a lot of farmland. At present, the average annual output of garbage in Beijing is 440 kilograms per person, which is about 4 million tons in the city, equivalent to two semi-scenic mountains. There are more than 4,500 garbage dumps in Beijing, covering an area of 1 1,000 mu. Garbage also stays in nature for a long time: cigarette butts and woolen goods are 1-5 years. Orange peel for 2 years; Painted wooden board 13 years; Nylon fabric for 30-40 years; Leather for 50 years; 80- 100 cans; Plastics 100-200 years; Glass 1000. Therefore, we should not only make less garbage, but also pay attention to the classification and recycling of garbage, so as to turn waste into treasure. We should use less disposable chopsticks, cups, lunch boxes and other products, and use more reusable products to reduce the consumption of precious forest resources. Use less plastic bags and shopping bags to reduce the harm of "white pollution" in cities; Buy fluorine-free refrigerators, air conditioners and other environmental protection appliances to protect the atmospheric ozone layer; Use less high-concentration detergent and phosphorus-free washing powder to reduce water pollution.

Second, pollute the air. Garbage is a complex mixture. In the process of transportation and open-air stacking, organic matter decomposes to produce stench, and a large number of pollutants such as ammonia and sulfide are released into the atmosphere, including 100 kinds of volatile organic gases, which contain many carcinogens and teratogens. Plastic film, paper scraps and dust fly with the wind, forming "white pollution".

Third, pollute the water. Harmful components in garbage are easily washed into underground water by rainwater, and a large number of acidic and alkaline organic pollutants will be produced during garbage stacking or pit filling, and heavy metals in garbage will be dissolved. Leachate produced by garbage pollution sources will penetrate into groundwater through soil; If garbage is directly dumped into rivers, lakes or oceans, it will cause more serious pollution. Look: plastic bottles and lunch boxes floating on the surface of the Summer Palace and Beihai, plastic bags and bread paper hanging on the branches scattered on the mountain roads of Xiangshan and Badachu forests. Some tourists only seek their own convenience, which will pollute the tourist environment. If animals eat white garbage by mistake, it will not only harm health, but even lead to death.

Fourth, soil and dregs. If garbage is directly applied to farmland or simply treated, it will destroy the aggregate structure, physical and chemical properties and water and fertilizer retention capacity of soil. In particular, if plastic bags and plastic sheets are buried in farmland, the roots of crops will not grow, the farmland will reduce production, and the food available for people will decrease.

Fifth, fire hazards. Garbage contains a lot of combustible substances, which will produce methane and other combustible gases in the process of natural stacking, and it is easy to cause fire in case of open flame or spontaneous combustion. With the increase of organic matter content in municipal waste and the change from scattered stacking in the open air to centralized stacking, the harm of biogas produced by long-term stacking of waste has become increasingly prominent, and garbage explosion accidents have occurred continuously, resulting in huge losses.

Sixth, the nest of pests. Garbage not only contains pathogenic microorganisms, but also provides food, shelter and breeding places for mice, birds and mosquitoes and flies, and is also the root of infectious diseases.

In a word, the seriousness and urgency of urban garbage problem is obvious. To turn this rubbish into treasure, we must recycle it. Do you know that?/You know what? Recycling 1 ton of waste paper can produce 800 kilograms of good paper, and cutting down less 17 trees can save more than half of paper-making energy and reduce 35% of water pollution. 1 ton of waste plastics can recover at least 600kg of gasoline and diesel; Using waste glass to rebuild glass can not only save quartz sand, soda ash and other raw materials, but also save electricity; Smelting metal with scrap metal can save a lot of energy consumption and reduce air pollution; Some kitchen waste, such as skins, eggshells, vegetable leaves and leftovers, can be treated by composting and fermentation to become green fertilizer.

Therefore, through various mass media such as television, radio, newspapers and information networks, we should vigorously carry out publicity and education on classified collection of garbage sources; Pay close attention to the formulation of laws and regulations on the classified collection and treatment of garbage suitable for the national conditions, and strictly implement them; It can be considered to carry out the pilot work of classified collection of garbage sources in some units in depth and in detail; We will further discuss with you how to improve the management methods so as to carry out the classified collection of source garbage as soon as possible. Let's work together to promote the classified collection of garbage, eliminate garbage pollution, turn waste into treasure, save resources, make Beijing win the right to host the 2008 Olympic Games with a brand-new look, and provide ourselves with a beautiful and healthy living space.

As a new material with light weight, waterproof and corrosion resistance, plastic products are widely used all over the world.

Plastic was first used in agricultural mulch film, which brought great development to agricultural production, made crops grow in all seasons and promoted market consumption. According to market statistics, since 1990 ~ 1995, the plastic output has increased by 8.9% every year, sweeping the world. It can be called the "white revolution". However, it provides convenience for people, and at the same time,

Today, "white pollution" has become a well-known new term, which mainly refers to all kinds of foamed plastic bags and agricultural plastic films that pollute the environment and arouse widespread concern in society.

Taiwan Province Province of China issued a ban on "white products" on 1994, and one year later, the ban was lifted.

As early as 1995, Hangzhou issued a notice prohibiting the local use of disposable foamed plastic tableware.

1 June, 1997, Guangzhou issued the * * * order, stipulating that from September of that year, the production, sale and use of disposable non-degradable plastic lunch boxes were prohibited in the whole city.

Based on this, in June, 1999, 1999, the State Economic and Trade Commission issued Order No.6, making it clear that disposable foamed plastic tableware, as an outdated product, will be completely eliminated before the end of 2000, and the production, sale and use will be completely banned from 200/kloc-0.

As can be seen from the above materials, the deadline has passed more than one year, but disposable foamed tableware can still be seen everywhere, and * * * has also changed from "white ban" to "ambiguity" at that time, and it is often perfunctory, and "white ban" has become a dead letter.

In view of the above situation, we have carried out various investigations and studies, consulted various materials, obtained all aspects of various new substitutes developed and put on the market by the state so far, and analyzed and summarized them.

A difficult journey

? We went to Xigu District Environmental Protection Bureau and received a warm reception. During the conversation, we realized the true composition of "white pollution", got a preliminary understanding of the concept of "white pollution" and got some understanding of the current plan to control "white pollution" (prepared a question and answer record).

? We went to Xinhua Bookstore, provincial library and school stacks, but there was little information about "white pollution", only the components of polyethylene, polypropylene and polyvinyl chloride, which hindered the research process.

? In order to get rid of the predicament, we decided to use today's information technology-surfing the Internet. On the internet, we found a vast space, which gave us a deeper understanding of "white pollution" and helped us write a great paper.

? With the above foundation, we decided to have a further understanding of the "white pollution" in Lanzhou. We interviewed Hualian Supermarket, Electric Supermarket, and some retail stores and vendors. We are deeply shocked. So many plastic belts are thrown away by foam lunch boxes every day, and people turn a blind eye to all this. We feel that it will be too difficult to solve the problem of "white pollution" without improving the quality of residents. Get ready.

"White pollutants", with such strong vitality, will bring serious harm to our lives, which we will describe in the following contents. First, let's learn about the composition of plastic.

I. Composition of "white pollutants"

"White pollution" mainly refers to white foamed plastic lunch boxes, various plastic bags, agricultural plastic films and other rings.

Environmental pollution. But "white pollution" is not what people usually think of as plastic products. As we all know, plastic is a new material with excellent comprehensive performance and a consumer product. Generally speaking, it is also a substance. Any substance has its life cycle, and the whole process of reaching the end of the life cycle is a degradation process. So the plastic itself is degradable. Just because of the stabilization technology, that is, adding light. Antioxidants delay or inhibit their inherent degradability. And there are more than 300 kinds of plastics, and there are more than 40 kinds in common use, but only a small part of them can really become white pollution. So "white pollution" cannot be equated with plastic.

The main components of "white pollution" are polyethylene (PE), polyvinyl chloride (PV), polypropylene (PP),

Polystyrene resin (PS). Let's do it one by one.

Polyethylene:

Polyethylene is a thermoplastic resin, which is formed by addition polymerization of ethylene. According to different polymerization conditions, polyethylene with relative molecular weight ranging from tens of millions can be obtained. Polyethylene is white particles or powder, translucent, non-toxic, tasteless, good chemical stability, acid and alkali corrosion resistance. Commercially, polyethylene is divided into low density, medium density and high density. Generally, it is mainly used for low-density packaging (0.92g/cm3-0.93g/cm3) without plasticizer.

Polypropylene:

The relative molecular weight is between 80000 and 200000. The main chain of polypropylene has a methyl side chain. If all methyl groups are distributed on one side, it is called isotactic polypropylene. If methyl groups are regularly distributed on both sides of the main chain, it is called syndiotactic polypropylene; If methyl groups are randomly distributed in the main chain, it is called random polypropylene. Polypropylene is usually a translucent solid, odorless and nontoxic, with a density of (0.90 g/cm3-0.9 1g/cm3), which has higher mechanical strength and better heat resistance than polyethylene. Among the three kinds of polypropylene, isotactic polypropylene has the largest output. Titanium trichloride-diethyl aluminum chloride is used as a catalyst for polymerization of propylene in saturated gasoline.

Polyvinyl chloride:

The relative molecular weight of PVC is 50,000-65,438+200,000. It is a thermoplastic resin, amorphous white powder, with a density of (1.35g/cm3-1.45g/cm3) and good chemical stability. It melts in solvents such as cyclohexene, chlorobenzene and dimethylformamide.

Polystyrene:

The average relative molecular weight is about 200,000. The colorless and odorless transparent resin has good light transmittance, glossy surface and flammability, and its density is (1.05g/cm3-1.07g/cm3). It has excellent water resistance, corrosion resistance and electrical insulation.

Production methods: bulk polymerization, suspension polymerization and emulsion polymerization. Ontology aggregation is introduced here. Initiator and a small amount of additives were added to styrene monomer, and then low-temperature polymerization was carried out in a prepolymerization kettle to prepare prepolymer, which was then transferred to a polymerization tower for high-temperature heating and kept at a certain temperature in stages. After the reaction, the molten polystyrene is extruded into strips, cooled and hardened in water, and cut and packaged.

These are the main components of "white pollution". In addition, plasticization is added to these pollutants.

Reagent, foaming agent, heat stabilizer, antioxidant, etc.

Second, the main reasons for the great harm of white pollution:

1. Main reasons:

? Plastic garbage has not been properly managed and treated, and garbage has not been collected separately, so it can be recycled.

Some of them have not been recycled, and the final disposal method of garbage basically stays at the level of * * * stacking or shallow burial. Some towns use rivers, lakes and coasts as natural garbage dumps.

? Transportation and tourism, except railways, have not yet established the courage to collect garbage suitable for production and operation.

Unified, let the garbage generated in the operation process drift with the flow.

? Weak management? Lack of relevant laws and regulations on plastic packaging waste, people's environmental awareness is relatively weak; Abuse and random dumping are quite common, which is not the responsibility of plastic products themselves.

2. Main dangers:

"White pollution" mainly refers to "visual pollution" and "potential harm" to the environment.

Effect.

"Visual pollution" refers to the plastic garbage scattered in the city and discarded by people, which is harmful to the city appearance and landscape.

The destruction of the landscape, such as a large number of polystyrene foamed plastic tableware scattered on both sides of the railway, rivers and lakes, and ultra-thin plastic bags flying all over the sky or hanging on branches, has brought people bad vision, which people have strongly reflected.

"Potential crisis" refers to the environmental problems caused by plastic waste entering the natural environment and being difficult to degrade.

Its hazards mainly include the following points:

? Recycling is not easy, because the recycling cost is high, but the utilization rate is low, so it can be said that businesses are unprofitable.

It is profitable and the recycling price is low, so it is difficult to attract the general public to carry out "white recycling".

So it's hard to recycle. -

? It is difficult to degrade. The recovered white waste is not easy to treat. At present, the main treatment method is incineration.

Incineration and landfill, if burned, will produce a lot of toxic smoke, pollute the atmosphere and promote acid rain.

As for the landfill, if it has been buried for 100 years, it is still intact and cannot be absorbed by nature.

But also do great harm to the land, change its pH value, affect the absorption of nutrients and water by crops, and lead to agriculture

As for plastic products discarded in water or on land, it will not only affect the environment, but also be passive.

If swallowed, it will lead to death. This will destroy the ecological balance.

? Decomposition of toxic substances at high temperature. Plastic products have no toxic substances, but they are profitable because of their recycling.

The equipment used is not perfect, the process is simple, and many manufacturers do not have legal business licenses, which leads to duplication.

When the temperature of plastic products reaches 65℃, toxic substances will precipitate and penetrate into food, which is harmful to the liver.

Viscera, kidney, reproductive system and central nervous system and other important parts of the human body cause damage.

Third, the reason why "white pollution" has a broad market and related problems in the process of governance.

Earlier, we mentioned the documents of the Economic and Trade Commission, and clearly pointed out: "By the end of 2000,

Eventually eliminate all foamed plastics. " But today, foam still exists, why does it still have such a strong vitality! The reason for this is the following：

? Degradable materials are not yet mature. Because of its complicated manufacturing process, its price is higher than "white"

Product "is 1 ~ 2 times higher, so people certainly don't want to" discard chaff and get expensive ". On the other hand, degradable materials

The performance of finished products is not as good as that of "white products" because the production technology of "white products" has gone through many years.

To sum up, it is now mature, new materials have just been developed, and some still need a lot of wood, although

The product is degraded, but it pollutes and destroys the ecology and water body.

? The crackdown is not strong enough. Now restaurants sell "white products", which are used quite well.

Universal, open and blatant market transactions ignore the provisions of the state, so that the "ban" has been repeatedly banned in recent years.

White jobs have become white bans.

? The national quality needs to be improved. The quality of a citizen reflects the national quality of a country, but

Today, people's awareness of environmental protection is still very weak, and the habit of littering is still very common. This phenomenon will bring great harm to our natural environment, and its appearance will bring great problems to the recovery of "white waste".

? The facilities for recycling "white pollution" are not complete enough. As mentioned earlier, "white"

The low utilization rate of pollution recovery is mainly due to the backward technology and insufficient capital investment in China, so some new products that have been studied in China cannot be put into production.

? Manufacturers from "open" to "semi-open", with the introduction of the national "white ban" policy, "white

Manufacturers of "products" have also moved from urban production to rural and suburban areas, and from open-air production to semi-open-air production. Because of the poor conditions, the products manufactured are unqualified, which brings difficulties to the "white ban". ;

As can be seen from the above examples, there are two main ways to solve "white pollution": recycling waste plastics and biodegradable plastics.

Answer: recycling waste plastics (that is, recycling waste plastics as resources, developing and utilizing them). )

(1) As a direct material, some renewable plastic products can be recycled, processed and then made into new plastic products.

(2) Preparation of synthetic polymer units. Polymers are polymerized from monomers, so they can be made from waste plastics under certain conditions. For example, polyester plastics can be made into monomers by alcoholysis.

(3) Preparation of fuel oil. The polymer chain will break at high temperature. For example, polyethylene and polypropylene can be decomposed into low molecular petroleum hydrocarbons at high temperature, and then fractionated to obtain various fuel oils.

Biodegradable plastics.

(1) natural polymer modification method. It takes starch, cellulose, chitin, lignin, seaweed and other natural polymers as raw materials, and transforms these molecules through chemical modification and polymerization to synthesize biodegradable plastics.

(2) chemical synthesis. Simulating the structure of natural polymers, starting with simple water molecules, active groups, such as amide groups, peptide groups and ester groups, are attached to the polymer chains of plastics. The compounds containing these groups are similar to the structural fragments of natural protein and oil, and are easy to biodegrade.

(3) Microbial fermentation method, many microorganisms can use some organic substances as carbon sources to produce polyester and polysaccharide polymers through metabolism, which are easy to degrade and can be further recycled.

However, some plastics are not suitable for recycling because of different material structures and some special additives; There are also some plastic fragments that degrade slowly in the natural environment and cannot completely solve the "potential harm" to the environment. Therefore, on the one hand, while controlling "white pollution", on the other hand, we should actively prevent the emergence of new "white pollution". Therefore, China's environmental protection department put forward that the prevention and control of white pollution should be "publicity and education as the leading factor, strengthening management as the core, and recycling as the main means"

Of course, "white pollution" is a worldwide problem, and due to limited development, we can't study it in depth. All we can do now is collect and sort out the data. But by studying this problem, we can also have a general understanding of "white pollution".

Although we have learned about the governance and solutions of "white pollution" in the world today, we still can't completely solve it. In the process of research, we deeply feel that people's low quality is serious to the environment. Only by raising people's awareness of environmental protection is the most feasible way to solve "white pollution".

At present, a large number of plastic products used in China's market are non-degradable plastics, which are made of expanded polystyrene, polyethylene or polypropylene with a molecular weight of more than 20,000. Only when the molecular weight is reduced below 2000 can they be used by microorganisms in the natural environment and become water and other organic substances, and this process takes 200 years. If it is buried, it will affect the absorption of nutrients and water by crops, resulting in reduced production; Burning it will release a variety of chemical toxic gases, including a compound called dioxin, which is extremely toxic. Even if ingested in a small amount, it can cause deformity and death of birds and fish and damage the ecological environment.

At the same time, it does great harm to people.