Valorization of spruce needle waste via supercritical extraction of waxes and facile isolation of nonacosan-10-ol

Supercritical carbon dioxide was utilized as a sustainable alternative to solvent extraction of waxes from the waste needles of two spruce species, namely Norwegian and Sitka spruce. These extracts were rich in nonacosan-10-ol, an organic compound with hydrophobic properties that lends its use in the preparation of superhydrophobic coatings. The highest crude yields were 1.7% w/w of needles obtained at 400 bar and 60 degrees C, while nonacosan-10-ol was selectively extracted at 200 bar and 60 degrees C (8070 +/- 91.1 mu g/g of needles). Purification of nonacosan-10-ol from the wax extracts was conducted using a simple rapid green recrystallization technique. This yielded a recovery of 44.6% +/- 2% and 48.4% +/- 2% of the total nonacosan-10-ol from the original crude Sitka (3600 mu g/g of needles) and Norwegian wax (1920 gig of needles) respectively. Application of nonacosan-10-ol to a filter paper led to the formation of highly hydrophobic surfaces, with preliminary contact angles of up to 149 degrees. This sustainable production method may develop opportunities to valorize forestry waste within a holistic biorefinery. (C) 2017 Elsevier Ltd. All rights reserved.