The Recycling of Polyethylene Terephthalate Michelle Chong Grace Kim Cluster 8 COSMOS 2007
Problem: MSW rate • The amount of municipal solid waste (MSW) produced in 2005 was 245 million tons. – 4.5 pounds of trash per person per day (http://www.epa.gov/msw/facts.htm)
Our Subject
– Recycled PET can be used for the same purposes
• PET should be recycled because it is not biodegradable • there are four main ways to recycle PET: – – – –
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• The recycling of polyethylene terephthalate (PET), which is common in textiles and plastic drink bottles.
Primary Mechanical Chemical Energy recovery
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Courtesy of http://www.cotton.org
Recyclable Plastics • Six classifications of plastics, each assigned a number: – 1. Polyethylene http://eng.amipak.by/i/photo/page/ production/peffilm/ttt-018-big.jpg Terephthalate – 2. High-density Polyethylene – 3. Polyvinyl Chloride of – 4. Low-density Courtesy http://www.airseacontainers.com Polyethylene – 5. Polypropylene – 6. Polystyrene http://www.flamar.it/images/tondi3.jpg
Courtesy of http://www.bayouplastics.com
Courtesy of http://www.a-plasticbag.com
http://www.path.cam.ac.uk/images/recycling/poly-chippings.gif
Primary Recycling • • • •
Deals with uncontaminated, clean PET It is popular and inexpensive There is a limited amount of PET available Product can be mixed with pure PET or used as second-grade material
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Mechanical Recycling • Contamination removal – PET is sorted, ground into flakes, and washed with detergent or a solvent – Flakes are dried thoroughly to prevent water from ruining the product
• Product – Flakes are melted and extruded – Possibly cross-linked to enhance properties
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Chemical Recycling • Hydrolysis – PET is depolymerized to terephthalic acid (TPA) and ethylene glycol (EG) by water in an acid, alkaline, or neutral environment – Requires high temperatures and pressures and takes a long time; costly
•Methanolysis
–Methanol depolymerizes PET to dimethyl terephthalate (DMT) and EG –High pressures and temperatures –DMT can be collected and used as a monomer to produce new PET
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Chemical Recycling ctd. • Glycolysis – EG is the reagent which partially depolymerizes PET into oligomers – The process produces bis(hydroxyethyl) terephthalate (BHET) – BHET is a substrate for the polymerization of PET • It can be collected and used to create new PET
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Recycling by Energy Recovery • Energy is recovered from PET by incineration – Process carried out in special chambers in waste-to-energy facilities Courtesy http://www.eia.doe.gov
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• PET has a very high stored energy value • There are 114 plants producing energy to power 1.2 million homes and businesses • There is a concern that incineration releases toxic substances into the air and is a hazard.
Plastic Factories • •
The first PET bottle was recycled in 1977. Generally, plastic bottles factories manufacturers prefer to use new resin rather than recycled because it is cheaper. www.formedfiber.com
www.selectdirect.us
PET (polyethylene terephthalate)
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• 95% plastic bottles are made from either PET or HDPE • PET makes up about 48% of all plastics • The recycling rates for plastic bottles however only remain at 25%. • The plastics that are not recycled will stay in landfills FOREVER and never degrade. www.packworld.com
www.townsville.qld.gov.au
PET Recycling • 167 million pounds of PET bottles were recycled last year…. But 271 million pounds still ended up going to waste. • In the United States alone, there are over 20,000 plastic recycling programs; 10,000 of them are only for PET bottles. • In 1996, 130 million cubic yards was conserved from landfills, and by 2005 it had increased to about 195 million cubic yards.
www.rirrc.org
Reduce, Reuse, Recycle
Did You Know? •
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Patagonia, Global Green, E-Wear, Deja Shoe, Wickers and Reebok are companies that use recycled PET plastic in their products. Carpet is also made from PET plastic because it is sturdier than most nylon. The bumpers produced by Ford Motor Company are made from millions of pounds of PET plastic.
www.myairshoes.com
www.carpetandcanefurniture.co.ukhttp://www.ci.keene.nh.us/publicworks/recycle/wearasodabottle.html
www.keilautogroup.com
Biodegradable Plastics • Though biodegradable plastics have been around for a long time, the high expense has never made it appealing. • The reasoning behind non-degradable plastics is because “their long polymer molecules are too large and too tightly bonded together to be broken apart and assimilated by decomposer organisms.” Gauss View
Polyethylene Terephthalate
Biodegradable Plastics ctd. •
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Starch, a natural polymer produced from corn, wheat or potatoes can be used in plastics because it contains the molecular structure that can be broken down by microorganisms. Due the fact that starch is soluble in water, it is first converted into lactic acid. The polymer, polylactide, is used in plastics. The price of biodegradable plastics being 2- 10 times more expensive than PET bottles, it is not very favorable in current markets. Lactic Acid
Courtesy of: news.softpedia.com commons.wikimedia.org
Credits • • • • • • • • • • • •
Awaja, Firas, and Dumitru Pavel. "Recycling of PET." European Polymer Journal 41.7(2005): 1453-1477. Lotfi, Ahmad. "Plastic Recycling." 25 July 2007 . "Municipal Solid Waste." 1 June 2007. U.S. Environmental Protection Agency. 25 July 2007 . "Plastics." 11 May 2006. U.S. Environmental Protection Agency. 27 July 2007 . Karayannidis, George P., and Dimitris S. Achilias. "Chemical Recycling of Poly(Ethylene Terephthalate)." Macromolecular Materials and Engineering 292.2 (2007): 128-146. Subramian, P.M. "Plastics recycling and waste management in the US." Resources, Conservation, and Recycling 28(2000): 253-263. http://www.scdhec.gov/eqc/outreach/pubs/9-12_37.pdf http://www.container-recycling.org/mediafold/newsrelease/plastic/2006-12-8PlasticBottleRecy.htm http://www.ci.keene.nh.us/publicworks/recycle/wearasodabottle.html http://www.napcor.com/funfacts.htm http://www.scdhec.gov/eqc/outreach/pubs/9-12_37.pdf http://biodegradableplastics.bio-tec.biz/
Acknowledgements Professor Patten Professor Tantillo TA Eric
Professor Allen Mr. Raymond
TA Mike
TA Slava
For all the help you’ve given ……
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AND OF COURSE…….
RA Mike & Kelsey
From: Grace & Michelle
