Prawn shells make an a-peeling catalyst for biodiesel production
The team, from Hua Zhong Agriculture University in the Wuhan province of China, found that carbonised chitin achieved a conversion rate of 89% in three hours – comparable with chemical catalysts.
Biodiesel production traditionally uses a liquid, inorganic catalyst such as sodium hydroxide. This has to be neutralised and washed after each use, creating large volumes of wastewater.
But carbonised chitin remains solid, and so it can be re-used up to ten times. Being organic, it is also biodegradable, and so, when eventually discarded, it is harmless to the environment.
China, the world’s biggest prawn producer at 1 million tonnes a year, may be unable to make much direct use of this technology: it cannot produce enough vegetable oil to satisfy its people’s culinary needs. But elsewhere in Asia, both vegetable oil and prawn shells are plentiful and cheap.
Some biofuel experts are cautious about the large-scale prospects of the technology. ‘For making and selling biodiesel locally it could work. But a big refinery might want something much more recyclable,’ says Richard Templer, director of the Porter Institute of biofuels at London's Imperial College.