An overview of Mechanical and Chemical Recycling Methods for Polyethylene Terephthalate Plastics

Abstract

Waste management has become one of the world’s most pressing issues. Plastic is one of the most widely utilized materials in the modern world. Plastic manufacturing and usage have risen globally in recent decades due to its low weight and outstanding mechanical properties. Global plastic waste volume was 6.3 billion metric tonnes in 2015, with an anticipated value of roughly 12 billion metric tonnes in 2050. Polyethylene terephthalate (PET), which is a polyester plastic, is one of the most widely used packaging materials for beverages. Due to its excellent transparency, lightweight, gas and water barrier properties, impact strength, UV resistance, and unbreakability (compared to a glass bottle), the production and use of PET bottles for beverage packaging has consistently increased worldwide. According to the United States Environmental Protection Agency (EPA) in 2018, 35.7 million tons of plastic waste was generated in the United States, which was 12.2% of total municipal solid waste (MSW). In addition to PET bottle wastes, this plastic waste included polyolefin and polyester bags, wraps, bottles, and jars. Approximately 27 million tons of plastic (18.5% of US plastic waste) was discarded into landfills. Only 4.5% of plastic packaging was recycled. Due to this high rate of consumption as well as the accumulation of PET waste in the landfill, developing processes for the recycling of PET packaging waste have become increasingly important. Various polymer recycling technologies have been developed to handle PET wastes and these include mechanical recycling, chemical recycling, energy recovery, or quaternary recycling. This paper explores some of the mechanical and chemical recycling methods available for recycling PET wastes into useful products from some published journal articles. It also evaluates the feasibility and techno-economic analysis of the methods as an efficient way of recycling PET wastes.