From crab shells to raw materials

(Nanowerk News) In a lab in Bavaria scientists are trying to chemically transform crab shells into a high performance biopolymer. This European research project, Chibio, turns the waste into a raw material and energy source. The first step is to extract the substance chitin from the shells. After cellulose, chitin is the most abundant biopolymer on earth.



Shrimps, crabs, crustaceans, a large proportion of their body weight contains chitin, says Prof. Dr Volker Sieber a biochemist at Fraunhofer IGBs Chibio Project.



Chitin is a polysaccharide, a polymer, which is composed of sugar molecules. Sugar molecules can be chemically or biotechnologically engineered to produce different molecules.



Crab shells contain other non-renewable biological substances. Used to produce biogas, they become a viable energy source. Meanwhile, biochemists from Munich have developed optimized yeast strains to convert the chitin through fermentation into fatty oils. The process takes between 5 and 7 days.

Once weve chosen the different yeast strains by fluorescence testing, we will intensify them in a fermentator to help produce enough oils for further experiments, says Dr. Daniel Garbe, a biochemist at Munich University of Technology.

These oils will be given to our partners in the industry to be processed. The oils we get by this procedure look like these samples.

The oils are sent to a partner company in northern Germany. Dr Matthias Ullrich a chemist with Evonik Industries explains the process: At this facility, we process the natural oil obtained from crab shells, a reaction takes place under high pressure and we obtain the raw material for our plastics.

The oil is transformed into a pure chemical, the raw material for the production of plastic. The next step is what is called polymerisation. The high performance biopolymer is produced in a reactor at temperatures of up to 300°C. Its then chopped into granulates.

We use this reactor, which can be thought of as a pressure cooker, and we fill it with raw materials, says Dr Ulrich. This raw material is what we transformed from the natural oil into a pure chemical by catalysis. After the reaction we obtain this high performance plastic as we see it here, which is cooled in water.

The biopolylmer is then molded into sample pieces for quality control; they are thoroughly tested.

From simple crab shells and a complex chemical process we finally end up with a high performance product, a raw material for the future, according to Dr. Joachim Leluschko an engineer with Evonik Industries: What is interesting with biopolymers is that we dont use any plants that are also used as a food source. We have a number of projects where we use organic wastes. Waste that would otherwise be destroyed, we can use it as natural raw material to make plastics in the future.