A new study has found that e-waste can be recycled and made into a hard, protective new material. In general, a typical “recycling” approach is to translate a large number of items made of a single material, such as aluminum cans or glass bottles, into more. However, due to the complexity and diversity of the materials made, it is not feasible to separate different materials and remove hazardous materials for things like e-waste.
Although it is difficult to recycle, as things stand, e-waste has to be recycled. First, the amount of e-waste is increasing – a recent United Nations study found that in 2016, humans produced 44.7 million tons of e-waste worldwide; Moreover, many rare materials are present in e-waste, which are valuable resources.
Materials scientist Veena Sahajwalla says:
We’ve developed a one-off mentality, that is, when we use something until it’s damaged, we want not to repair it but to throw it straight away. Not in need of it, or no longer need or no longer want it, and then we get rid of it,” he further explains, “if we have unlimited resources and unlimited disposal space, this treatment is certainly not a problem, but the point is that this is not the case.”
Veena Sahajwalla co-founded the Centre for Sustainable Materials Research and Technology at the University of New South Wales, Sydney, Australia.
Previous studies have shown that by heating, the link between different materials in e-waste can be selectively broken and modified to create new environmentally friendly materials. For example, glass in electronic waste can be used for valuable silicon ceramics, while plastic parts are a good source of carbon.
Veena Sahajwalla stresses that there are many valuable elements in these wastes that can be converted into new products, which is exciting, as an example, in some e-wastes, such as printed circuit boards, containing 10 to 20 percent copper, while copper mines contain up to 3 percent.
In the new study, researchers delved into the properties of copper and silica compounds, which are often found on worn-out printed circuit boards and computer monitors. The researchers speculated that extracting the substances from e-waste could combine them to form a new, durable blend that could protect metal surfaces from corrosion and wear.
In specific experiments, the researchers first heated the plastic powder on the old computer monitor screen and housing to 1500 degrees Celsius, creating a silicon carbide wire 10 to 50 nanometers (one billionth of a meter) in diameter. Next, they combine the substance with copper recovered from the circuit board, place the mixture on the steel surface, and heat it to 1000 degrees Celsius. This step melts the copper, creating a 1 micron-thick film on the top of the steel. Moreover, the researchers stress that the width can be adjusted from micron to nanoscale.
In other words, the structural combination of different elements creates new performance that is superior to the respective master materials. For example, the toughness of the metal material is good, but the hardness is poor; After understanding the properties of the raw materials, by setting different temperatures, the two materials are cleverly combined to not only recycle valuable materials, but also create a new blend of ceramic hardness and metal-like toughness. Moreover, these materials can be collected entirely from e-waste, preventing these valuable resources from being buried in landfills.
The researchers found that the surface hardness of the steel was increased by 125 percent as a new type of micro-micron-thick substance was added. In addition, microscope images show that when the material is knocked, the hybrid layer remains firmly bound to the steel and does not break or peel easily.
Veena Sahajwalla says:
For a long time, humans have relied on mining to obtain the raw materials needed, but at the same time, large quantities of e-waste with rare metals have been abandoned in landfills. As a result, the dump may be a good place for us to “exploit” our resources in the future.