Physicochemical properties of maize cob cellulose powders reconstituted from ionic liquid solution Chukwuemeka P. Azubuike • He ´ctor Rodrı ´guez • Augustine O. Okhamafe • Robin D. Rogers Received: 7 October 2011 / Accepted: 24 November 2011 / Published online: 8 December 2011 Ó Springer Science+Business Media B.V. 2011 Abstract Suitable a-cellulose and cellulose II pow- ders for use in the pharmaceutical industry can be derived from maize cob. a-Cellulose was extracted from an agricultural residue (maize cobs) using a non- dissolving method based on inorganic substances. Modification of this a-cellulose was carried out by its dissolution in the ionic liquid 1-butyl-3-methylimida- zolium chloride ([C 4 mim]Cl), and subsequent regen- eration by addition of either water or acetone at room temperature, or of boiling water. X-ray diffraction and infrared spectroscopy results showed that the regen- erated celluloses had lower crystallinity, and proved that the treatment with [C 4 mim]Cl led to the conver- sion of the crystalline structure of a-cellulose from cellulose I to cellulose II. Thermogravimetric analysis and differential scanning calorimetry data showed quite similar thermal behavior for all cellulose sam- ples, 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 a-cellulose sample, evidencing an influence of the regeneration strategy on the resulting powder after the ionic liquid treatment. Keywords Agricultural residue  Antisolvent  Cellulose  Ionic liquid  Maize cob Introduction Cellulose, the major constituent of plant materials, forms about one-third to half of plant tissues and is constantly replenished by photosynthesis. It is non- toxic, renewable, biodegradable, and modifiable, and C. P. Azubuike Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, University of Lagos, Lagos, Nigeria C. P. Azubuike  H. Rodrı ´guez  R. D. Rogers QUILL, School of Chemistry and Chemical Engineering, The Queen’s University of Belfast, Belfast BT9 5AG, Northern Ireland, UK H. Rodrı ´guez Department of Chemical Engineering, University of Santiago de Compostela, E-15782 Santiago de Compostela, Spain A. O. Okhamafe Department of Pharmaceutics and Pharmaceutical Technology, Faculty of Pharmacy, University of Benin, Benin-City 300001, Nigeria R. D. Rogers (&) Center for Green Manufacturing and Department of Chemistry, The University of Alabama, Tuscaloosa, AL 35487, USA e-mail: rdrogers@as.ua.edu 123 Cellulose (2012) 19:425–433 DOI 10.1007/s10570-011-9631-y