Much of the planet is swimming in discarded plastic, which is harming animals and possibly human health. Not all plastics are degradable, there are Non-biodegradable plastics that can be broken down into tiny pieces "microplastics" and powder harming the food chain, and oceans, thereby impacting the ecosystem.
There are Photo-degradable and oxo-degradable plastics that break down readily when exposed to heat and light. These Photo-degradable plastics such as PP, PE, PET, etc. have some catalytic additives which help the products to biodegrade. The transition metals such as Magnesium (Mg), Zinc (Zn), Nickel (Ni), and Manganese (Mn) are the additives used in the polymer. These additives are susceptible to heat, light, and mechanical stress that weakens the tensile strength of the polymer chain.
Can conventional plastics be replaced? Can Biodegradable plastics help?
In India many companies offered bags and biomedical products made of Bioplastics. These Bioplastics are made from renewable biomass sources such as sugarcane and corn. Chemists are working on creating polymers which can replace Poly-ethylene (PE) as well as polymers for industrial and medical applications.
Are Bioplastics a solution to stop pollution?
Bioplastics are chemically identical to conventional plastics like PET, PE, and PP. These bioplastics contribute less than 1% to the overall contribution of plastics. Bioplastics are bio-based but not biodegradable which means they cause the same pollution as normal plastics do. If bioplastics are decomposed in the right environment, it releases methane on decomposition which can be used to produce energy.
What is the point of producing them?
Bioplastics are obtained from renewable biomass which means we are independent of oil or fossil resources and this has a very good impact on the whole carbon footprint, saving Carbon dioxide and the plants take this Carbon dioxide. Plastics obtained from plants do not biodegrade which means it still needs to take to landfills and will cause the same pollution as normal plastics.
Growing plants to make plastics causes other issues:
Critics say they put pressure on land.
Bioplastic farms could lead to diversity and increase in monoculture cropping, pesticides, and water use.
When it comes to producing them in the labs the challenge for the chemists is to form a material that has all the necessary and desired functions of their product and is a food for microorganisms..
Bioplastics are not an effective solution to plastic pollution. Although, the concept does provide us hope for more ways to innovate. The need for biodegradable raw materials and the challenge that exists to process them properly prove that we need a systematic change where resources are reused, redesigned, and valued.
"The challenge in the way of bio-plastics fulfilling their eco-friendly purpose is that most of them require industrial composting facilities to be disposed of. But most cities lack an adequate number of such facilities. And eventually bio-plastics end up in the landfills, harming the environment and defeat the very purpose of tackling plastic pollution."Prof. S K Bansal, Department of Biochemistry, Chandigarh University
We require a raw material that is solely bio-based and biodegradable. Poly (lactic acid) (PLA) and poly (hydroxyl alkanoates) (PHA) are some bio-based and biodegradable plastics. Whereas bio-based poly (amides), poly (ethylene), and poly (ethylene terephthalate) are examples of bioplastics that are bio-based but non-biodegradable.
Poly (hydroxyl alkenoates) (PHA) are polyesters produced from renewable feedstock. PHA is synthesized inside the bacteria that involves an enzyme PHA synthetases. Depending on the specificity of enzymes and the carbon source in the growth medium, varying properties and compositions can be generated. Due to their bio-based and biodegradability, they are environmentally friendly, PHAs have gained immense attention as industrial replacements for conventional non-biodegradable plastics. But due to the relatively high costs of PHAs production and their downstream processing, the use of PHAs as industrial plastics is still limited.
However, with the development of large-scale production, the use of PHAs is likely to expand.