Nuclear techniques to recycle plastics and promote circular economy
Plastic pollution is one of the greatest environmental problems today.
According to The New Plastics Economy, report from the Ellen MacArthur Foundation, , in 2025 the ocean will contain one ton of plastic per every ton of fish, and in 2050 there might be more plastic than fish in the ocean. Landfills, always brimming with plastic waste, are a serious threat to rivers, underground water and oceans.
Nuclear technology can help convert plastic waste into raw materials, contributing to a circular economy that is more sustainable and makes better use of raw materials.
A study reveals that, if we don’t take proper measures, at the present rate we are going there could be more plastics than fish in the ocean by 2050
Traditional recycling of plastics
Usually, plastic recycling operations do not use radiation. Whilst they are very useful, they can only produce products with less demanding technical requirements, such as these school desks.
Plastic waste is usually composed of mixed plastics, mostly domestic waste such as single-use packing. As it is a mix of various types of plastics with different properties, they are very difficult to recycle.
To recycle mixed plastics, they are first cleaned and crushed. Afterwards, they are mixed in different proportions (soft and hard plastics) along with an aluminium base to control the density of the final product. This mix is introduced into an extruder, where it is melted and homogenised at a temperature of 150-200 degrees Celsius (hot enough to melt the plastic but not too hot to avoid degradation). This limits the release of toxic gases.
But the properties of this final product are limited, and it can only be used to create basic products.
Recycling mixed plastics with radiation
If the recycled plastic had better thermodynamic properties, the possibilities would be a lot greater. There would be more demand and a market for plastic recycled through radiation at industrial level, which at the same time would reduce the demand for virgin plastics.
Radiation can increase the thermodynamic properties of mixed and recycled plastics. This opens a wide range of much more versatile possibilities of reuse for the plastic
The Philippine Nuclear Research Institute in Davao, south of the country, has launched a special program to recycle plastics with nuclear radiation techniques, with the support of the International Atomic Energy Agency (IAEA).
The IAEA has launched a program to recycle plastics with nuclear radiation techniques
First, small plastic pellets are introduced into a container. The container is placed inside a small radiation device with self-shielding (at an industrial scale, bigger devices will be needed.)
The plastic pellets are irradiated until they receive an optimal predetermined dose. During irradiation the polymers in the plastic become more reactive, which means that when the plastic is melted there will be structural changes in the polymers and it will also be easier to mix the different components found in the waste.
The irradiated pellets are then mixed with the ground mixed plastic. After this, the same process of plastic extrusion and melting is repeated, only this time it uses natural fibres modified by radiation.
Once homogenised and melted, the plastic is covered by water to cool it off. Afterwards it is introduced into a machine that cuts it into very small pieces. The result is a much more sturdy plastic that maintains its original stiffness and hardness.
These plastic pellets are ready for a wide variety of uses, even for high value products such as construction materials and mechanical pieces.
The result of the irradiation of plastic waste is a much more sturdy plastic that maintains its original stiffness and hardness
Once this technology has been adapted at an industrial scale, it would be of great help to support a circular economy and keep the beaches and oceans in Philippines cleaner.
In the future, the technique can be applied in many other places to help take care of the environment and reduce plastic pollution.
Source: Miklos Gaspar (OIEA)