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Ecological plastic, as it is showed by the biggest bioplastic companies, is not any worse that the synthetic one, having identical qualities, not being fragile or brittle. The one made from starch is also biodegradable in normal composting conditions and, what is even more interesting, it can be prepared at home, much easier than it may seem. All you need to do is eat a few bananas.

What to do with the skin?

We all know it as a great source of vitamins B6 and C, magnesium and potassium. Some of us also think about it as a kind of fruit that prevents cancer, cardiac infarct and helps healing hypertension. Yet those are just some of the most important qualities of a fruit that is produced in a quantity exceeding 145 million tones yearly worldwide - the banana.

Little do we know, that what we throw away after eating the fruit, and of which 200,000 tones  are produced every day in Thailand only, the banana skin, has much more usefulness to it. It can replace the ubiquitous synthetic plastics and be called bioplastic. Ecological, cheap plastic to make at home? Why not?

Young scientist

Project to develop bioplastic from discarded banana skins, conducted by Elif Bilgin won the Scientific American’s “Science In Action” award, and overall Google Science Fair 2013 contest in the 15-16-year-old category (This year Scientific American’s Science In Action Award Winner will be announced on  August 6). The 16-year-old Turkish girl noticed the fact, that banana skins are rich in starch and they can therefore be used to produce bioplastic. Developing the procedure to be easy, yet effective and to make the product durable took her two years.

Baked bananas plastics. How?

The instruction is really easy, it is recommended to choose green-yellow bananas:

Ingredients

  • Banana peel
  • Distilled water
  • 0,5% Na2S2O5 solution
  • 3ml 0,1 or 0,5M HCl
  • 3ml 0,1 or 0,5M NaOH
  • 2ml propan-1,2,3-trio
  • Glass pipette
  • Beakers
  • Bunsen burner
  • Glass stirring rod
  • Oven
  • Petri dish
  • Gauze pad
  • Blender

Recipe

  1. Prior to the boiling and pureeing processes it is necessary to dip the banana skins in 0,5% Na2S2O5 solution.
  2. Fill the 800ml beaker with distilled water and place it over a Bunsen burner.
  3. Place the banana skins in the beaker and boil them for 30 minutes.
  4. After the boiling process remove the beaker from the Bunsen burner, decantate the water off the skins, and cover them with a dry gauze pad, leaving to dry for 30 minutes.
  5. After drying the peels, place them in 800ml beaker, puree using hand blender until a fluid paste is formed.
  6. When the banana paste is created, you can start producing plastic. Put 25ml of paste in 50 ml beaker, add
    1. 3ml HCl,
    2. 2ml of propan-1,2,3-triol,
    3. 3ml NaOH,
    stir the mixture after every step.
  7. Pour everything into a Petri dish
  8. put it in the oven at 130°C to bake for half an hour

Indeed, the recipe is not complicated, and all the ingredients are easy to get. According to the project’s author, the method is not developed to be used for industry (just wait until you see separate bins for banana skins), but mainly – at home. Will you give it a try?

Sorce: GSF 2013


That’s interesting:

The biggest bioplastic producer is American NatureWorks, that uses mainly field corn. It is good to know, that potatoes or cereal can be used just as well. They contain starch (same as in banana skins), which is natural biopolymer.

Samanta Makurat

Chemistry student at the University of Gdańsk, fascinated with molecular modeling. Nature enthusiast.

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