Industrial valorization of Quercus cerris bark: Pilot scale fractionation

• Stepwise fractionation is proposed for valorisation of raw Quercus cerris bark.
• Pure and enriched cork fractions (8.4% and 18.5% respectively) were obtained.
• Low-cost Q. cerris bark may be integrated into the cork granulate production.

Cork-rich Quercus cerris bark collected from Turkey was fractionated in a laboratory and in a pilot-scale equipment to obtain cork and phloem fractions. After a primary trituration as a field post-harvest operation, the cork-rich bark granules were mainly concentrated in the big granules (>12 mm) indicating different mechanical properties of cork and phloem. The smaller granules (<4 mm) could be fractionated using water flotation by separating a floating cork fraction. The pilot-scale fractionation consisted of a mechanical grinding of the whole bark fractions followed by a granulometric and a densimetric separation. The operation was quite efficient and as a result, pure cork (8.4% wt) and cork-rich (18.5% wt) fractions were obtained. The colour analysis and FTIR spectroscopy showed the separation efficiency of the cork fractions. The results show the potential of Q. cerris bark for production of valuable cork fractions and the efficiency of combined granulation and fractionation.

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