By the year 2050, there could be more plastic in the ocean than fish, and 80% of all drinking water will contain microplastics. This is the why part of the story- read on to find out how bioplastics can help in setting back the plastic doomsday clock.
Biodegradable plastic or bioplastics are just plastics, but if you give them the right conditions, they can be broken down completely into water, carbon dioxide and compost by microorganisms. Given the exponentially growing critical status of plastic pollution, bioplastics are sound alternatives due to their ability to degrade into products that can be used by members of the ecological chain.
Although the concept of “biodegradable plastics” sounds like it’s off a shelf from this millennium, celluloid was developed as early as the 1860s from cotton and camphor, and in 1941, Henry Ford made an entire car out of soy-derived plastic! A good question to ask at this point would be, “Well, why didn’t these investment sustain through the centuries?” Although it was novel and exciting, bioplastics were still very costly to manufacture, and were not as sturdy as synthetically derived plastics.
In 1990, NatureWorks, owned by Cargill, the world’s largest corn merchant, further researched the problem and, in 2000, collaborated with Dow Chemical Company to manufacture polylactic acid (PLA) from corn. Rising oil cost and increasing awareness caused to increase in production of greener products like corn plastic more attractive from a business standpoint. At the beginning, it costed $200 to make one pound of PLA; now it’s less than $1. The material got its biggest boost when Wal-Mart, the world’s largest retailer, announced in 2006 that they would sell some of their produce in PLA containers. The move was a part of company’s effort to counter criticisms that it has been environmentally irresponsible. Wal-Mart planned to use 114 million PLA containers a year, which company executives estimate will save 8,00,000 barrels of oil annually. Now, PLA is used in many medical implants due to its nature to degrade into non-toxic products, apart from plastic films, bottles and 3D printer filament.
How is corn-plastic made?
Corn-starch is one of the major ingredients for manufacturing biodegradable plastic. Bioplastics are produced using a mixture of glycerol, corn-starch, vinegar, and food colour and heated to give a good yield. Notably, bioplastics in general require a starch which can be polymerized and processed, so other sources of starch such as cassava, sorghum fill, etc. can also be used. Corn is currently the preferred source of starch as it contains 18.2% starch by weight.
First, the harvested corn crop is soaked and ground to separate endosperm from gluten and fibre. Then enzymes are used to extract dextrose from starchy endosperm. Then huge fermenters convert dextrose to lactic acid. The resulting acid consist of lactide molecules, which bond into long chains called polymers. Finally pellets of polymer (polylactic acid), is spun of into fibres or melted to take any form.
To initiate bio-degradation, corn plastic is kept at 140 degrees Fahrenheit for 10 consecutive days to facilitate composting, but can take up to 90 days in high humidity environments to decompose completely. Aerobically, microbes convert the lactic acid to under high oxygen supply. Alternatively, they can also be degraded by anaerobic microbes and the methanol released can be stored as fuel.
Corn is a renewable source, and releases less toxins during both production and treatment. A 2017 study determined that switching from traditional plastic to corn-based PLA would cut greenhouse gas emissions (in the US alone) by 25 percent. Producing plastics from corn produces much less greenhouse gas emissions than conventional plastics. In terms of energy, the manufacture of corn-based polymers require 65% less energy compared to a similar polymer made from petroleum.
Since petroleum prices are steadily going up, popularity for bio-plastics is increasing. Furthermore, there is no danger of explosion in bio-plastics manufacture, since it does not involve petroleum-based starter material. Biodegradable plastics are easy to recycle and can be decomposed, and add to the nutrient composition of soil, which is beneficial for agriculture.
Plastics are one of those utilities that we cannot stop using abruptly- they are practically everywhere around us. But small, conscious acts of switching to non-plastic or bioplastic alternatives can shift consumer behaviour towards more sustainable options. If you don’t know what to do, just remember- If you can’t reuse it, just refuse it!
References:
Comments