Physicochemical properties of maize cob cellulose powders reconstituted from ionic liquid solution

Suitable alpha-cellulose and cellulose II powders for use in the pharmaceutical industry can be derived from maize cob. alpha-Cellulose was extracted from an agricultural residue (maize cobs) using a non-dissolving method based on inorganic substances. Modification of this alpha-cellulose was carried out by its dissolution in the ionic liquid 1-butyl-3-methylimidazolium chloride ([C(4)mim]Cl), and subsequent regeneration by addition of either water or acetone at room temperature, or of boiling water. X-ray diffraction and infrared spectroscopy results showed that the regenerated celluloses had lower crystallinity, and proved that the treatment with [C(4)mim]Cl led to the conversion of the crystalline structure of alpha-cellulose from cellulose I to cellulose II. Thermogravimetric analysis and differential scanning calorimetry data showed quite similar thermal behavior for all cellulose samples, although with somewhat lower stability for the regenerated celluloses, as expected. The comparison of physicochemical properties of the regenerated celluloses and the native cellulose mainly suggests that the regenerated ones might have better flow properties. For some of the characterizations carried out, it was generally observed that the sample regenerated with boiling water had more similar characteristics to the alpha-cellulose sample, evidencing an influence of the regeneration strategy on the resulting powder after the ionic liquid treatment.