As we know, protecting environment is becoming more and more important to our human beings, now european researchers are working to improve their recycling system by a new technique, which is called magnetic density sorting.

This method was developed to help handle the 14 million tonnes of polyolefins to be get recycled every year. This type of plastic, also known as polyalkenes, is a family of polymers which are used to make packaging items like water and soft drink bottles. Unfortunately, these common plastics are not biodegradable, and can only be recycled into new plastic products when it is available in pure form. This meant the recycling process has been expensive, complicated and time consuming.

However, researchers with W2Plastics have developed a method for recycling polyolefins in one step based on their specific weight. A researcher in resources and recycling at the Technical University of Delft in the Netherlands, has lead a team that has developed this magnetic density sorting method.

How Magnetic Density Sorting Works
This magnetic separation system works by dredging the plastic waste through a tank that holds a suspension of 5-nanometre iron oxide nanoparticles. The plastics are then placed over a magnet, which attracts the iron oxide particles and artificially increases the density of the liquid. Because the density of the liquid is at its highest at the bottom of the container, so when the plastic flows through the tank, it sorts itself into different layers that match the density of each type of plastic flake. The plastics are then gathered from each layer, and sorted by type.
However, there is no guarantee that this method will be an economically viable worldwide. For example, industries who manufacture polymers are generally not also included in the recycling industry, often seeing the recycling of their products as a conflict of interest.

Critics have also pointed out that polyolefins are not toxic, meaning the motivation to keep them out of landfills is reduced. Magnetic density sorting is currently an expensive process, and its use of energy and transport means it is not necessarily “green.”

However, even critics agree that the technique is worth exploring and developing, as it could have untold applications in the future.