ISOLATION, CHARACTERIZATION AND MODIFICATION OF CELLULOSE DERIVED FROM Dioscoreabulbifera

Abstract

Biomass materials,dioscoreabulbifera,from different locations (Isarun and Ondo road in Ondo State and Iyin-Ekiti in Ekiti State)were investigated in this study.The biomasses were separated into peels and bulbils by mechanically and carefully removing peels from the biomass. The peels and bulbils were individually treated with different solvent mixtures in order to separate extractives from the remaining lignocellulosic components. Thereafter, lignin, hemicellulose and cellulose were isolated from the extracted biomass using standard methods. The isolated cellulose was mercerized using 20 wt. % NaOH and then functionalized by esterification reaction with maleic anhydride dissolved in acetone. Physicochemical parameters such as pH, moisture content, bulk and tapped densities were determined for the biomasses.The isolated products and functionalized cellulose were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry Analyzer (TGA), X-ray Diffraction Spectroscopy (XRD) and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray (EDX) Spectrometry. Ethanol-benzene mixture had highest percentage yieldfor the extractives followed by ethanol-cyclohexane which could serve as a greener alternative solvent-mixture in place of the former. The chemical composition analysis showed that dioscoreabulbiferapeel from Isarun had the highest percentage of cellulose 82.6%,holocellulose of 89.45%, lignin content of 23.2%,and contain the least percentage composition of hemicellulose 6.85%, Ekitibulbi has the least value of the cellulose content of (30.74%) and has the highest percentage composition of lignin(49.9%) and hemicellulose (49.66%). Ondo peel bulbihas the least percentage of holocellulose 62.43% butthe highest percentage of extractive content (13.90%). In the physicochemical properties, the moisture content of all the biomass materials are the same 0.92% which showed that irrespective of their locations they all have equal inherent water retention properties while the pH obtained showed the alkalinity of the biomass except Isarun peel with pH of 6.2. The bulk and tapped density ranged from 0.19g/cm3– 0.55g/cm3and 0.55g/cm3- 0.56g/cm3 respectively. FT-IR results showed the presence of a very strong carbonyl (C=O) adsorption band at around 1724cm-1.SEM images and XRD data showed clear decrease in crystallinity after modification of the mercerized cellulose and specific surface area became larger due to the heterogeneous surface. TGA results showed the rapid weight loss of the cellulose (290oC-380oC) which reflects thermal degradation of the polymers.