Green carbon

Researchers at the National Institute of Advanced Industrial Science and Technology (AIST) in Japan have developed a process for producing ultra-lightweight hollow carbon fine particles from lignin, a by-product obtained in large quantities during the manufacture of paper.

In the process, the researchers first mixed lignin with an inorganic salt to form a complex. They then pyrolysed the complex at 600°C to 800°C, washed it and finally dried it to yield sub-micrometre-sized hollow carbon particles or nanometre-sized hollow carbon particles with diameters in the range of 3nm to 30nm.

Since these hollow carbon particles have large surface areas and the fabrication process can be controlled to obtain carbon particles with good elasticity, the researchers are now examining potential uses for them.

They believe that rubber or plastics could be reinforced by these particles, instead of the carbon black that is traditionally used for the purpose. About 10 million tons of carbon black is produced every year. However, it is usually produced by pyrolysis of oil at high temperatures of around 1,400°C.

The Japanese method of producing the carbon particles could offer an environmentally acceptable alternative.