Preparation and characterization of cellulose by delignification of Eteng (Ceiba pentandra) wood in formic acid-acetic acid-water solvent mixtures

Abstract

Abstract Cellulose is a natural polymer obtained from plants with applications in various industrial sectors such as pulp and paper, textiles, coatings, fiber composites, and nanomaterials. This work studied the extraction of cellulose from a tropical agricultural plant residue (Ceiba pentandra) using formic acid (FA)-acetic acid (AA)-water (Wa) mixtures as a function of temperature, time, and composition the cooking solvent mixture. Three different volume ratios FA: AA: Wa of 50:30:20, 40:40:20 and 20:30:50 were investigated. Reaction temperature was varied between 80° and 107°C and the duration between 40 and 200 min. The efficacy of the cooking reaction was determined by the fiber percent yield and kappa number of the cooking residue. Cooking residues with relatively higher yields (50–70%) were obtained compared to the conventional Kraft method. The residues with yields between 50–60% were bleachable as revealed by their Kappa numbers of around 10–12. Some residues were bleached and the products were characterized by Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analyses (TG-DTG) and X-ray diffraction (XRD). The results showed that the bleached products had properties close to those of commercial cellulose exhibiting almost similar FTIR spectra and TG-DTG curves. The activation energy of the cellulose was between 93–141 kJ mol-1 showing that, for the case of high activation energy (141 kJ mol-1), cellulose of high quality was obtained. Formic acid, acetic acid and water mixtures can be used as relatively a soft route (at mild temperatures, atmospheric pressure) to produce cellulose from the tropical lignocellulosic residues of Ceiba pentandra.