Plastic waste is regarded as a potentially cheap source of chemicals and energy. Lots of us have encountered a variety of products that use plastic materials today. As a result of the increasing level of private consumption of these plastic materials huge amount of wastes are discharged to the environment.
Plastic materials are a type of material that cannot be decomposed easily in a short period of time. Substantial quantities of plastic have accumulated in the natural environment and in landfills. Those wastes can be classified according to their origins. They are
These groups have different qualities and properties and are subjected to different management strategies. Huge amounts of plastic wastes arise as a by-product or defective product in industry and agriculture.
The main components of municipal solid waste (MSW) are food waste, wood, paper, cardboard, plastics, rubbers, fabrics, and metals. On the other words, more than half of the municipal solid waste components are organic species mainly thermoplastics, which can be used as energy sources.
The traditional MSW disposal method is landfill. Because of the longevity of plastics, disposal to landfill may simply be storing problems for the future. For example, plasticizers and other additive chemicals have been shown to leach from landfills. The extent of varies accordingly, particularly pH and organic content.
Recently, the conception of energy recovery from MSW has been a very hot topic. It is also undesirable to dispose of waste plastics by landfill due to poor biodegradability.
PYROLYSIS OF PLASTIC: Pyrolysis is a process of thermal degradation of plastics in the absence of oxygen. There is total conversion of waste plastics into value-added fuel products. All plastics are polymers mostly containing carbon and hydrogen and few other elements like chlorine, nitrogen, etc. When this long chain of polymers breaks at certain points, or when lower molecular weight fractions are formed, this is termed as degradation of polymers. This is reverse of polymerization or de-polymerization. If such breaking of long polymeric chain or scission of bonds occurs randomly, it is called Random depolymerization. Here the polymer degrades to lower molecular fragments. In the process of conversion of waste plastics into fuels, random depolymerization is carried out in a specially designed reactor in the absence of oxygen and in the presence of coal and certain catalytic additives. The maximum reaction temperature is 350°C.