Abstract
Microwave-assisted extraction (MAE) is a very effective and sustainable method for extracting cellulose from lignocellulosic materials due to the substantial reduction in the process time and amounts of solvents required for each process. Deep eutectic solvents (DES) are used for cellulose extraction due to their environmental friendliness and high extraction yields. This work explores the possibility to use microwave-synthesized DES to extract cellulose from olive wood powder (OWP) waste. The conventional process (CP) requires the use of high amounts of chemicals and long times for quantitative extractions. Three techniques for the cellulose extraction were compared: a standard procedure by Technical Association of the Pulp and Paper Industry (TAPPI), CP, and MAE utilizing DES to evaluate the effectiveness of these techniques. Results showed that the TAPPI method yielded 55.0 wt% cellulose, whereas the CP method yielded 50.6 wt% cellulose. The optimum conditions for MAE using choline chloride-lactic acid (ChCl:LA, 1:4) and choline chloride-citric acid (ChCl:CA:H2O, 1:1:6) were found to be 20-min irradiation time at 130 ºC to obtain cellulose yields of 47.8 wt% and 45.6 wt%, respectively, showing that both DES were effective for cellulose extraction from OWP. The comparison between all procedures showed that MAE required shorter times and smaller quantities of chemicals, making it an eco-friendlier option. The extracted cellulose was characterized by thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and Scanning electron microscopy (SEM). Results suggested that MAE with DES is a promising approach, with prospective applications in the packaging, textiles, and paper industries.