Ultrasonic-assisted water extraction from Eucalyptus globulus leaves and branches, to obtain natural textile dyes with antioxidant properties

Forestry is an interesting source of fibres and metabolites with high applicability for the textile industry and one of the main alternatives to reduce its high environmental impact. In recent years, the use of forest raw-materials as sources of dyes and natural fibres for the textile industry has gained interest due to environmental and sustainability concerns. The feasibility of the valorisation of Eucalyptus globulus small branches and leaves (BLE) as a raw material in the production of extracts that allows the production of functional dyed textiles with antioxidant properties was evaluated. The ultrasound-assisted extraction (UAE) in water methodology was used, as it is environmentally friendly, and the impact of the BLE particle size distribution on the phenolic content and antioxidant activity of the extracts was determined. Chemical characterisation of the extracts was performed by LC-ESI-LTQ-Orbitrap-MS and FTIR. The extracts obtained were used to dye and functionalise cotton textile samples, evaluating the effect of using alum as a mordant and NaOH as a pH modifier on the properties of the dyed textile products. It has been shown that it is possible to obtain dyed textile products with interesting colour and light fastness properties only by using BLE extracts as natural textile dyes. Furthermore, the dyed textile products obtained showed interesting antioxidant properties, with the best results obtained when only BLE extracts were used as dyes. • Valorisation of Eucalyptus globulus small branches and leaves by ultrasound-assisted water extraction was studied. • Particle size distribution impact on the extracts properties was evaluated • Antioxidant activity and chemical composition were evaluated, with hydrolysable tannins being the main components of the extracts. • The extracts were used to dye and functionalise cotton textile samples and the impact of pH and mordant use was studied. • Dyed textile products with interesting colour and antioxidant properties were obtained using only extracts of leaves and small branches of Eucalyptus globulus as dyes.