What is the Biodegradation of Plastics?

Fossil fuel-based or bio-based plastics are called biodegradable plastic. Degradation of the plastic by the microbial action for the formation of the natural product is called biodegradable plastic. The end product of biodegradable plastics is carbon dioxide and water. To decompose the plastics the specific requirement is needed including time, temperature, and environmental conditions. Production of biodegradable plastic is usually done by the petrochemicals, microorganisms, and raw material or sometimes all of them. There are three kinds of plastics. Biodegradable plastic, bioplastic, and eco recycled plastic. Bioplastic is one that is made from natural materials such as starch and corn. Biodegradable plastic is made from petrochemicals. Eco-recycled plastics are plastic that is made from recycled materials.

Classification of Plastics:

Plastics can be divided into two groups based on the thermal properties:

Thermostatic Polymers:

This plastic cannot melt and remain solid and can be modified. The plastics are not recyclable as they have a cross-linked structure therefore the chemical change is irreversible. The example of the thermosetting plastics is polyurethanes and phenol-formaldehyde.

Thermoplastics:

When heated the thermoplastics are the plastic that can not change and hence undergo modeling many times. These polymers are of different types such as polyvinyl chloride, polystyrene, etc. this plastic is derived from the simple monomer unit.

Synthetic and Biodegradable Plastics:

The chemical properties of the plastics can differentiate them into degradable plastics and nondegradable plastics. The plastic that is nondegradable is called synthetic plastic which is a derivative of the petrochemicals and which is a heavyweight. Whereas biodegradable plastic is made from renewable sources like cellulose, starch, living plant, and algal material. These plastics are a breakdown in the interaction with the water; UV and change in the pH also change in the enzymes. There are four types of biodegradable plastics compostable bioplastic, photodegradable bioplastic, bio-based bioplastic, and biodegradable bioplastic.

Types of biodegradation:

Aerobic biodegradation:

The natural attenuation of contaminants in many hazardous waste sites is an important part of aerobic biodegradation. The aerobic microbes as electron acceptors use the oxygen and then break down the large organic chemicals into the small organic chemicals. In this process, the water and carbon dioxide is the end product of the reaction

Anaerobic biodegradation:

In anaerobic biodegradation, the organic contaminants are breakdown by the microbes when oxygen is not available. Some of the microbes used sulfate, iron, nitrate, and carbon dioxide as electron acceptors to break down the large organic chemicals into small organic compounds. From the outer cell membrane, the microorganism is unable to transfer the polymer inside the cell so the biochemical process will not take place. By using material like carbon as an energy source the microbes developed a phase in which they release the extracellular enzymes that enzymes outside the cell depolymerize the polymer. During the degradation, the microbial enzyme cut the complex polymers and converted them into small chains like monomers, dimmers, and oligomers, etc. the initial process of the degradation is called the depolymerization and when the end product will form in inorganic species it is called mineralization.

Biodegradation Mechanism:

The polymers of the biodegradation have the following steps: ·The microorganism is attached to the polymer. ·By using the polymer as the carbon source the growth of the microorganism ·Degradation of the polymer. The microbes attach to the surface of the polymer when it is hydrophilic. When the microbe attached to the surface it is growing by using the carbon source from the polymer. In the starting the extracellular enzymes which are released from the organism causing the cleaving of the chain and form the low weight molecule like monomers, dimmers, etc. This low-weight molecule is further used by the microbes as an energy source.

Factors affecting the biodegradation of Plastic:

1.Functional group that increases the nature of the hydrophobicity.

2.Density of the polymer and the molecular weight.

3.Structural complexity like linearity.

4.Morphology of the compound.

5.Molecular composition.

6.Existence of the easily breakable compounds.

7.Nature and the physical formation of the polymer.

8.Hardness.

Advantages:

Biodegradable plastics reduce the level of carbon dioxide. As these plastic breaks down naturally and depositing the amount of the gas back to the environment. ·Reduce the emission level of greenhouse gas. If the plastic is recycled every year then 30% of the carbon is saved. ·The naturally occulting bacteria are broken by the biodegradable plastic. ·On the decomposition, the biodegradable plastic does not release any kind of harmful item. ·In the manufacturing cycle, biodegradable plastic consumes less amount of energy. ·For the other needs, the biodegradable plastic is direct petroleum consumption. ·The traditional products are mixed with biodegradable plastic. ·New export industries are made due to biodegradable plastic. ·New marketing platforms is made due to the biodegradable plastic. ·In a specific situation, biodegradable plastic decomposes quickly.

Disadvantages:

A specific disposal procedure is required to dispose of. Small pieces of metal are present in the biodegradable plastic. ·Weather requirement is necessary. ·For herbicides and pesticides, biodegradable plastic does not account for. ·Reduce the amount of recycling. ·The ocean pollution problem is not solved. The higher cost required. ·Croplands needed to produce items. ·Methane is used for the production of biodegradable plastic.

Conclusion:

Fossil fuel-based or biobased plastics are called biodegradable plastic. Degradation of the plastic by the microbial action for the formation of the natural product is called biodegradable plastic. The end product of biodegradable plastics is carbon dioxide and water. To decompose the plastics the specific requirement is needed including time, temperature, and environmental conditions. Production of biodegradable plastic is usually done by the petrochemicals, microorganisms,s and raw material or sometimes all of them. There are three kinds of plastics. Biodegradable plastic, bioplastic, and eco recycled plastic. Bioplastic is one that is made from natural materials such as starch and corn. Biodegradable plastic is made from petrochemicals. Eco-recycled plastics are plastic that is made from recycled materials.