Don’t Throw Away your Future with Plastic Packaging: Recycling
In the global world, the increase in population and the change in living standards increase the rate of production and consumption on day to day. With the increase in the rate of production and consumption increasing of using of plastics which makes our lives easier, all around the world.
After consumption, plastics are generally left to landfill casuing to environmental problems by humans. Today, most of the products that are thrown away as litter, people are throwing them away, ignoring their future. In this way, environment is polluted, the ecosystem is damaged, and as a result of unconscious behavior, most living things are deprived of their right to live. For this reason, various steps are taken to ban single-use plastics and bags, especially by European countries.
Despite such environmentalist approaches, it seems impossible for us to give up the comfort that plastics provide to our lives. Instead, environmental pollution can be prevented by making more environmental friendly regulations in the consumption and production of plastic. As long as people do not give the necessary value to the environment and plastics, various environmental and economic problems will continue to occur despite all prohibitions. 150-200 million tons of 359 million tons of plastic produced worldwide are thrown into the landfill. This is not due to the plastic itself, but to people’s post-consumer behaviors. In our country, recycling studies have been emphasized in recent years, and separation studies at the source have been initiated with the Zero Waste Project. Separation of plastic waste at its resource increases the recycling rate and reduces the recycling cost.
About 60 percent of the plastic produced in Europe is used in packaging and consumer products. In Turkey, 37 percent of the products used in the packaging industry consists of plastic packaging. Poly(ethylene terephthalate) (PET), which is widely used in the packaging industry, creates waste accumulation all over the world. PET accounted for 23 percent of the total plastic raw material produced in Turkey in 2019.
PET, which was commercialized by DuPont in the 1950s, is a polymer widely used in many industrial applications such as fibers, foams, films, thanks to its low production cost, high gas barrier (oxygen and carbon dioxide), thermal resistance and recyclability. PET, which started to be preferred in bottle production in the 1970s, is the most recycled plastic packaging material in Europe. According to the OECD 2018 report, 970 thousand tons of PET wastes were recycled in the United States in 2014.
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Figure 1: a) PET bottle wastes on the landfill b) Disposal of PET bottle waste at resource.[/caption]
Although bio-based raw materials have been used in the production of PET bottles recently, it is accepted that the most effective method is recycling to reduce the effects of PET on environment. Recycling of PET has gained importance in terms of minimizing environmental problems and sustainable production. Recycling studies of PET bottles first started in the 1970s with the aim of improving waste management. PET wastes are classified as post-industrial and post-consumer wastes. Post- industrial wastes are formed a result of flakes or manufacturing defect in the production of PET. Post-consumer wastes, on the other hand, are considered as waste created by the consumer after use. PET wastes are recycled in two main method which are chemical and mechanical recycling.
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Figure 2. Life cycle of PET bottle.[/caption]
PET waste, which is generally used in water, beverage and oil bottles in the packaging industry, is mechanically recycled after being collected from the landfill. In 2015, 0.51 million tons of 0.6 million PET wastes were mechanically recycled in Japan. Mechanical recycling, it consists of removing pollutants, shredding, washing, separation by density difference, drying and melt processing. In the phase of removing contaminants, PET
wastes are separated from other types of plastics, metal and other materials.
After this stage, PET wastes are classified according to their color, ground and cleaned
by washing. After the washing phase, the drying process is applied to the PET wastes. Dried PET wastes can be reprocessed and used in industries such as packaging, automotive, textile and furniture.
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Figure 3. Recycled PET bottle waste by mechanical recycling.[/caption]
During reprocessing and “active life”, PET exposure to various factors such as mechanical forces, aging, acids and detergents which changes its structural and physical properties. It is limiting the application areas of recycled PET. In order to improve the structural and physical properties of recycled PET, different methods such as vacuum systems, solid state polymerization (SSP) and chain extension are preferred. Recycled PET raw material produced by these methods is used instead of pure PET.
Chemical recycling of waste PET is a very costly method. In this method, depolymerization of waste PET is carried out by chemical reactions such as pyrolysis, alcoholysis, hydrolysis, glycolysis, and methanolysis. The chemicals obtained as a result
of recycling can be used in the synthesis of PET or in the synthesis of polymers such as alkyd, polyurethane, unsaturated polyester and epoxy resin. With the pyrolysis process, PET wastes are burned and used for energy recovery. Since waste PET harms the environment when burned, this method is not preferred much.
Every waste product that can be recycled adds value to the economy as it can be used as raw material. Postconsumer PET bottle is not waste, but actually a resource of raw materials. Recycling PET waste ensures more efficient use of resources and minimizing the environmental impact of wastes released into the landfill. Although PET bottle waste is not large in weight, it constitutes a very important ratio in terms of volume. For this reason, the separation of PET bottle waste at the resource is of great importance in terms of recycling and energy use.
As a result of, the reduction of PET wastes released to the environment, it ensures that less raw materials and intermediate products are used in production. Bringing a circular life to PET bottles will contribute greatly to the economy in terms of raw materials, energy efficiency and sustainable consumption.
References
S. Devasahayam, G. B. Raju, C. M. Hussain, Utilization and recycling of end of life plastics for sustainable and clean industrial processes including the iron and steel industry, Materials Science for Energy Technologies 2 (2019) 634–646.
Tournier, V., Topham, C.M., Gilles, A. et al. An engineered PET depolymerase to break down and recycle plastic bottles. Nature 580, 216–219 (2020).
OECD, Improving Markets for Recycled Plastics: Trends, Prospects and Policy Responses, OECD Publishing, Paris, (2018).
Türkiye Plastik Sektör İzleme Raporu, PAGEV, (2019).
https://sifiratik.gov.tr/plastik-atik
Aysun Ekinci
Yalova University
Vocational School
Department of Materials and
Materials Processing Technologies
Prof. Dr. Mustafa Öksüz
Yalova University
Engineering Faculty
Department of Polymer Materials
Engineering
