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A second life for low‐grade wool through formation of all‐keratin composites in cystine reducing calcium chloride–water–ethanol solution
Author(s) -
FitzBinder Christa,
Pham Tung,
Bechtold Thomas
Publication year - 2019
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.6151
Subject(s) - wool , keratin , solvent , chemistry , materials science , composite material , composite number , dilution , dissolution , fibroin , pulp and paper industry , chemical engineering , waste management , organic chemistry , silk , medicine , physics , pathology , thermodynamics , engineering
BACKGROUND Coarse low grade wool holds a share of more than 40% of the worldwide production of 1.2 million tons per year. Wool hair with a diameter above 32.5 μm and recycled wool waste represent an important source of high quality keratin. An efficient and simple shaping procedure to form all‐keratin composites could open a new approach to utilise wool keratin for production of sustainable and biodegradable all‐keratin composite. RESULTS In this work the dissolution and regeneration of wool keratin was studied using a concentrated solution of calcium chloride–water–ethanol as solvent and thioglycolate as reducing agent to open disulphide bonds. Up to 70% of the wool keratin dissolved in the solvent at pH 7, 60 °C. After dilution with water a share of 80% of the total keratin could be obtained as regenerated composite structure while 20% of the protein remains in solution. Based on the model studies, all‐keratin composites were prepared by impregnation of wool with solvent followed by thermal consolidation in a heated press at 60 °C and 2.2–3.3 bar pressure. CONCLUSIONS The new method for production of all‐keratin composites permits production of a protein‐based bio‐composite, which opens new applications for low value coarse wool and recycled wool waste. By use of cheap chemicals and thermal consolidation in standard equipment scale‐up of the technology is expected to be straightforward and commercially feasible, leading to a bio‐based and biodegradable composite material. © 2019 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.