Shrimp-shell biodiesel

Scientists in China have found a way to produce a highly efficient catalyst for the production of biodiesel from vegetable oils...using prawn shells. Linguo Yang and his colleagues Hua Zhong Agriculture University in Wuhan, China, have found that if prawn shells (currently discarded by the tonne by the seafood industry) are partiallycarbonised by heating them to a high temperature they can be "functionalised" by adding potassium fluoride (KF) which sticks to the carbon scaffold. The result, which they are presenting in the journal Energy and Fuels, is a very high surface area catalyst (13 square metres per gram!) that can be used repeatedly (over ten times) to produce biodiesel from vegetable oils.

The major benefit of this approach is that making biodiesel at the moment involves the use of strong acid or alkali catalysts which are potential environmental contaminants and are also hard to recover for reuse from the reaction mixture during each batch of production. This makes the process both economincally and ecologically costly. But the shrimp-shell catalyst retains its activity and is very easy to recover, clean and regenerate, retaining 87% of its original activity even after the ten round of processing!