**2.3 Isolation of acetylated xylan**

A sample of 6 g of delignified biomass (holocellulose) which was done either by PAA or by NaClO2 was treated with 130 mL of DMSO, at room temperature for 24 hours, under inert atmosphere with constant stirring. Subsequent to the treatment, the suspension was filtered through a polystyrene membrane (porosity 60 μm) followed by washing with ∼20 mL of distilled water. The filtrate was added to 600 mL of ethanol at pH 3.5 (adjusted with formic acid) and left for 12 hours at 4°C. The precipitated xylan-rich hemicelluloses were isolated by centrifugation and washing properly with methanol. The xylan-rich hemicelluloses were dried in a vacuum oven at 50°C for 24 hours. The total yield was calculated gravimetrically on oven dried basis of extractive-free biomass.
