APPLICATION OF DES (DEEP EUTECTIC SOLVENTS) TO WOOD EXTRACTIVES

Abstract

Deep eutectic solvents (DES), known as environmentally friendly, recyclable, non-poisonous, low volatile, non-flammable and harmless are first found by Abbott et al. in 2003. In the last decade, scientists are working with DES in different areas. Mainly, they focus on isolation of cellulose and lignin. Regard to extractives, to the best of our knowledge DES was not studied before. In this study, it was aimed to determine the extractive composition of Scotch pine with deep eutectic solvents. Pinus sylvestris L. was used as wood material. As deep eutectic solvent (DES) Choline chloride (Merck 5.00117), ethylene glycol (Merck 1.00949) and urea (Merck 1.08487) were used with molar ratio of choline chloride; ethylene glycol (1:2 m/m), and choline chloride: urea (1:2 m/m). Sequential soxhelet extraction was performed first with n-hexane and then acetone-water with 5 g wood sample for 6 hours. With DES two extractions were performed in an ultrasonic (UB) and hot-water bath (HWB) at 60°C for 30 min. 0.05 g wood samples were used for these extractions. Identification and quantification were done with GC-MS and FID-GC. Similar results were obtained with DES and organic solvents. Fatty acids, resin acids and stilbenes are the main chemical groups. Oleic acid (1.4-9%), linoleic acid (1.6-8%) and levopimaric acid (0.6-17.7%) are dominant compounds, found in all extracts. Also, monomethyl pinosylvin (51.5%) was found in acetone: water mixture. DES can be an alternative to organic solvents in wood extraction.