Chemists at the University of Birmingham have found a new way to make nanostructured carbon using the waste product sawdust, according to research published in the Royal Society of Chemistry journal Green Chemistry.
By cooking sawdust with a thin coating of iron at 700 degrees centigrade, the researchers found they can create carbon with a structure made up of several tiny tubes. These tubes are one thousand times smaller than an average human hair.
Scientists are looking for new ways of making carbon nanomaterials because they can be expensive and difficult to manufacture. Carbons with a very specialized structure have many different applications — for example, carbons with very small pores are used in water treatment for removing pollutants and in soil remediation where they can help to retain moisture and nutrients. More advanced carbons are finding use in batteries and may also be used in future hydrogen-powered cars.
There are many different types of carbon nanostructure, the researchers say. The most well known is graphene, which has a shape resembling chicken wire — hexagonal mesh with a carbon atom in each corner. Carbon nanotubes are similar — they are made of layers of graphene rolled into tubes. The organized shape of these materials means that they have interesting properties such as conducting electricity — but they are expensive and difficult to produce on a large scale. The challenge is to make carbons with similar properties, but in a much simpler way.
Sawdust is made up of fibers of cellulose and lignin, two of the main building blocks of all plants. When the whole surface of the sawdust is coated in iron nitrate and then cooked, iron carbide nanoparticles are produced. These tiny particles burrow through the structure of the wood as it is decomposing to carbon, leaving behind tubes of very ordered carbon resembling more conventional carbon nanotubes.
In August, another group of scientists at the University of Birmingham released an announcement calling for soft furnishings to be discarded with the same caution as electronics. Waste from soft furnishings such as curtains, cushions and sofas contain brominated flame retardants (BFRs), which have been shown to damage the environment and human health. In the United Kingdom, at least two thirds of electronic waste (e-waste) must be treated before it can enter landfill. However, the millions of tons of furniture and textile waste disposed of by UK households each year currently goes unregulated. Most of this waste ends up in landfill, while the rest is incinerated.