Recycling Plastics
Plastic is recycled every day. Most people recycle many things every day, but they may
not understand what they are recycling. They just look at the bottom of the bottle, can, or
other recyclable, see that is has a number, and throw it in their recycling bin. But the recycling
of plastics is more complex than just recycling any bottle.
There are numbers on the bottom of every recyclable that shows what chemical is in the
plastic, and how easily the plastic is to recycle. There are seven numbers. Number one has the
chemical polyethylene terephthalate, number two has the chemical high-density polyethylene,
number three has the chemical polyvinyl chloride, number four has the chemical low-density
polyethylene, number five has the chemical polypropylene, number six has the chemical
polystyrene, and number seven has anything else. Despite what most people believe, not all
plastics are recycled. First, number seven, the other plastics, are rarely, if ever, recycled in
factories because it is made of mixed resins that are extremely difficult to recycle. This would
be found in objects like electronics, baby bottles, lids, medical storage containers, and sports
water bottles. Second, number six, polystyrene, can be recycled, but is not normally recycled.
These are found in objects like CD cases, food containers, egg cartons, and insulation in walls.
Third, number five, polypropylene, is hard to recycle too because the type and concentration of
polypropylene is inconsistent, making it hard to make an effective way to recycle all
concentrations at once. This can be found in outdoor carpet, clouded plastic containers, and
deli soup containers. Fourth, number four, low-density polyethylene, is also rarely recycled. It
is found in most plastic wraps, grocery bags, and some bottles. Fifth, number three, polyvinyl
chloride, is the least recyclable plastic because it has harmful chemicals that are formed when it
is being destroyed or disposed of. This is found in chemical household cleaner bottles, shower
curtains, flooring, and food packaging. Sixth, number two, high-density polyethylene, is easily
recycled, and created back into a new container. This is found in milk and water jugs, shampoo
bottles, and some plastic bags. Lastly, number one, polyethylene terephthalate, is easily
recycled, and it is the most common plastic recycled in the United States. So, only two of the
numbers on plastics are regularly recycled.
There are many ways to recycle plastics. Polyethylene terephthalate (PET) is the most
commonly recycled plastic, so it is the most important to learn about. It has four main ways to
be recycled. It can go through primary recycling, mechanical recycling, energy recovery
recycling, and chemical recycling. The first three are simpler, and less chemical. Primary
recycling is inexpensive, and used a lot. It uses PET in its purest state and is then mixes it with
as second material that is then used as the new plastic. However, there is a limited amount of
pure PET to use. In mechanical recycling, polyethylene terephthalate gets pounded into flakes,
which are them washed. The flakes is left to dry because the water can destroy the finished
product. The flakes are then melted and are usually used in other materials. Energy recovery
recycling is when polyethylene is incinerated so they release a large amount of energy.
However, this releases toxic substances that are then released into the air.
Chemical recycling is more complex and there are three types of recycling. First,
Hydrolysis is when PET gets depolymerized, when a polymer is broken down into monomers. It
is broken down to terephthalic acid and ethylene glycol. This happens by water in an neutral,
alkaline, or an acid environment. It takes a high amount of pressure and temperature for this
to work, and it is a long process that costs a lot. The second type of chemical recycling is
Methanolysis. This is when PET is depolymerized into dimethyl terephthalate and ethylene
glycol. This process also needs high temperatures and pressure. However, in this process, the
monomer dimethyl terephthalate can produce new PET. The last type of chemical recycling is
Glycolysis. It is when PET is depolymerized into oligomers by ethylene glycol. This produces
bis(hydroxyethyl) terephthalate which can also be used to directly make new PET.
There are many plastics, however; only a couple of the existing plastics are usually
recycled. But, the plastics that are recycled are recycled in different ways. So, depending on
where someone lives, different plastics are recycled in different ways. So, it is okay to just
throw any plastic in your recycling bin because there is a chance that the community recycles it.
“Smart Plastics Guide” pbs.org. Institute of Agriculture and Trade Policy. N.d. Thursday 3.
January 2013. Web.
Chong, Michelle and Kim, Grace. “The Recycling of Polyethylene Terephthalate.” N.p. 2007.
Thursday 3. January 2013. Web.