Plastic packaging waste and value-added approach to recycling

First, the hazards of plastic packaging and waste to humans

The harm to the human body from the discard of plastic packaging has gradually been known. Through research shows that plastic packaging, especially as a food or food-related items, because of its plastic polymer are polymerized, many of which contain chlorine, benzene, it is inevitable to produce harmful gases, resulting in its contents Things have gone sour, and even some carcinogens have penetrated into foods, causing consumers to suffer.

The pollution caused by plastic packaging waste cannot be ignored. In addition to the use of plastic waste, most of the people were burned and buried, and some were dumped into rivers, lakes and seas, and were discarded at will. According to calculations, paper products can be rotted in seven days, while plastic can survive for 3 to 400 years. A large amount of waste plastics lands in the landfill with garbage, and stays in the soil, destroying the daring properties of the soil, reducing the water storage capacity of the soil, and affecting the absorption of water and nutrients by the crops, resulting in the reduction of crop production. Plastic waste dumped into rivers, lakes, and seas, once eaten by aquatic organisms, will cause massive deaths. Treatment with incineration also causes secondary air pollution and is harmful to humans.

In summary, the environmental pollution and human hazards of waste plastics have become a major public hazard. Therefore, the advantages of plastic packaging are gradually weakening, and the demand for elimination of plastic packaging is increasing in many countries.

Second, the international response to plastic packaging waste

1. Use legal means to prohibit or restrict the use of plastic packaging products to enhance recycling. For example, Italy passed a bill prohibiting the use of non-biodegradable plastic sundry goods in Italy. For another example, Japan has long established a treatment and public health law that enables most of the packaging waste to be recycled and used to control the use of plastic that cannot be recycled. The Netherlands also issued relevant laws and regulations in this regard. In addition, the United States, Denmark, the European Union and other countries and regions have also formulated relevant laws and regulations.

2. Gradually weed out plastic packaging and take it out of paper packaging. The food packaging is particularly prominent. For example, the U.S. government has made strict regulations on food packaging, requiring that the bag packaging must be physically decomposed into plastic packaging. DuPont also developed a new paper pocket called tyrek. Japan Watanabe Paper Company immediately used its materials to make a new type of bag for packaging milk, dairy products, and feed. Switzerland and Germany also said that they will gradually phase out plastic packaging. The United States now has 50% of its packaging changed to new paper bag packaging.

3. Research and promotion of biodegradable plastics that are harmless to the environment and humans are being stepped up. There are two types of biodegradable plastics, one is microbiodegradation and the other is photodegradation. The principle of its degradation is through the role of microorganisms in the soil or ultraviolet light in the sun without human effort, so that the polymer polymer chain breaks, eventually breaking down into carbon dioxide, etc., so that the plastic will degrade in the short term. The earliest research on degradable plastics began in the 1950s. At present, there are mainly three methods for producing degradable plastics, namely the use of microorganisms, biomass energy and chemical synthesis.

Third, China should take measures in the face of plastic packaging

At present, research and development of degradable plastics and their application are imminent. From now on, we should step up and step up the research and application of degradable plastics. According to studies, biodegradable plastics are relatively mature and their technical difficulties are lower than photodegradation technologies. Therefore, priority should be given to research and development. At the same time, we must actively seek alternatives for plastic packaging in order to stabilize the competitive position of China’s exports of goods in the international arena.

In the interim period, it is very necessary to seek for the collection, utilization, and appreciation of plastic packaging waste. First of all, traditional plastic packaging has to be replaced, while other plastic products cannot be eliminated and the demand will increase. Under such circumstances, it will be a valuable task to seek comprehensive utilization of plastics and plastic waste to achieve turning waste into treasure and countering damage.

China's plastic raw materials are very privately owned, with large import volumes and high prices. Moreover, China’s population accounts for 1/4 of the total population of the world, and the output of plastic products is only a little over 2% of the world’s output. The average per capita consumption of plastic products in China is 150-200kg lower than that of developed countries, and it is also lower than the world average per capita consumption of 31kg. In the new century, China still needs to import more than 1 million tons of plastic raw materials annually. It can be seen that China's plastic raw material is very scarce. If you recycle waste plastics and use them, you can save a lot of money. If recycling one ton of polyethylene, it can save 1.1 tons of ethylene raw material or 3 tons of gasoline. Therefore, it is necessary to recycle used plastic packaging for recycling.

China has great potential for recycling and using waste plastics and its packaging. The recycling rate of waste plastic packaging is less than 10% in China, and Japan has reached 26%. It can be seen that recycling plastics has great potential.
The use of recycled plastics can not only reduce production costs, but also help reduce environmental pollution. In recent years, the high price of plastic raw materials has made plastic waste recycling more important. Especially in developed countries, many scientists and departments are studying their value-added recycling methods.

Fourth, recycling methods and methods

Through research, the following major applications are currently: 1) production and manufacture of building materials; 2) manufacturing of general supplies; 3) production of chemical products; and 4) production of gasoline and diesel.

1. Building materials. Waste plastic building materials, mainly made of waste polyvinyl chloride, polystyrene. This kind of plastic building material has the advantages of moisture-proof, anti-corrosion, sound-insulating and non-deteriorating. It can be used to make river embankments and lakeside revetments, doors and windows, wall partitions, etc. It can replace wood and cement. In this respect, we have a wide gap compared with some foreign countries. Therefore, the domestic market for plastic building materials has great potential. For example, wood plastic raw materials and processing methods. Its raw materials are mainly made of thermoplastics, wood, wood flour, high-temperature mixed torches, and high-pressure molding. The texture is superior to wood and has a wide range of uses.

2. Daily necessities. The production of stools, tables, sleeping flags, conveyor tables, livestock and poultry barracks, etc. using waste plastics is achieved by melting, squeezing, and processing the different types of mixed plastic packaging waste. Some European countries have also produced special machinery and equipment for this research.

3. Chemical Products. The use of waste plastics to obtain chemical products has a wide range of products and methods. Listed below are the methods and uses for mechanical sealants, dry paints, adhesives, and polyethylene waxes. It is worth mentioning that among them, polyethylene wax is a chemical product with a high quality and a shortage in the domestic market, mainly relying on imports. Its use is very wide.

4. Fuel. Many countries and regions have conducted a lot of exploratory research in this area and have made great progress. Taiwan and Japan and other regions and countries have no longer developed a process for extracting energy products such as fuel from waste plastics.

Table 1 List of Chemical Products Made from Waste Plastics

Product name Waste plastic variety Preparation method Main use Mechanical sealant Waste polystyrene Add a certain amount of Alkaline and dibutyl phthalate, Heat in agitating and cooling machinery in the reaction kettle Oil, Water seal Dry paint waste Concentrate Ethylene is added into rosin, glycerol oxidizing glass, xylene, etc., put into the polymerization vessel, colored, dispersed, ground, and sieved to obtain the same purpose as the common dry paint. Adhesive Waste Polystyrene Add Ethyl Acetate, Methyl Acetate , dissolving, stirring and sticking carpets, sand and gravel flooring, etc. Polyethylene waxes are easy to clean waste plastic films, plates, pipes, plastic buckets, etc. Polyethylene waste plastics are depolymerized at specific temperatures, times, and pressures. Plastic Additives, Paints, inks, paint bases. Wax absorbers, anti-moisture agents, lubricants, antioxidants, etc.

Japan's methods and processes are the use of a thermal reforming method, in which a catalytic reducing agent is used to reverse the three common waste plastics from the catalytic process of the torch plastic from petroleum to obtain fuel oil. One kilogram of waste plastic can be used to obtain half a litre of gasoline, half a litre of kerosene and diesel. The cost of converting one ton of waste plastic is about $230.

Taiwan's method is a thermal decomposition method. In a sealed high-pressure pyrolysis reactor, waste plastics are heated to convert the macromolecules of the constituent plastics into low-molecular compounds, and then oil-vapour separation columns are used to make oils of different molecular weights and vapors. Respectively, they will get gasoline, diesel, solvent oil, heavy oil, liquefied gas and other products. The recovery rate is about 65%. 3000 tons of waste plastic can be torched into 2000 tons of high-purity gasoline.
With the advancement and development of science and technology, more advanced, more applicable methods and processes will continue to emerge and be adopted.

V. Conclusion

In summary, the traditional plastic packaging will be replaced by a new type of detachable plastic packaging or paper packaging. Starting from the country’s national conditions and national strength, the recycling and utilization of plastic packaging discarded will bring more social and economic benefits. Therefore, it is very feasible and necessary.

Source: China packaging industry Author: Wang Min