Alkali and bleach treatment of the extracted cellulose from pineapple (<i>Ananas comosus</i>) leaves

Abstract

We successfully extracted cellulose from pineapple leaves (Ananas comosus) using alkali
treatment and bleaching. Alkali treatment was done using aqueous sodium hydroxide while
bleaching was done using acetate buffer and aqueous sodium chlorite. The extracted cellulose
was characterized using Scanning electron microscopy (SEM), Fourier transform infrared
(FTIR) spectroscopy, Thermogravimetric analysis (TGA) and Differential thermal analysis
(DTA). SEM micrographs revealed that alkali treatment removed the impurities in the
pineapple leaf fibers and subsequent bleaching further purify the fibers leaving mostly
cellulose only while hemicellulose and lignin are removed as revealed in the FTIR spectra.
TGA spectra further revealed that alkali + bleached treated sample slowly degrade at
temperature between 160 °C and 355 °C suggesting that small amount of hemicellulose and
lignin are present as compared to the untreated sample. This finding was also confirmed in the DTA spectra suggesting that high quality of extracted cellulose is produced.

Keywords: Pineapple leaves; Cellulose; Alkali treatment; Bleaching.