The effect of active alkali and sulfidity loading on the kraft pulp properties of sweet sorghum bagasse

Abstract

A study was carried out to observe how active alkali and sulfidity loading affect the kraft pulp characteristics of sweet sorghum bagasse (SSB). SSB pulp was obtained from the kraft pulping with a variation of active alkali (17, 19, and 22%) and sulfidity loading percentage (20, 22, and 24%). The chemical functional group and composition, morphological properties, crystallinity, and pyrolysis product of the resulting pulp were characterized. Based on Fourier transform infrared characterization, SSB pulp demonstrated a peak absorption showing the existence of cellulose, lignin, and hemicellulose. The fibril was found clearly in the pulp fibers of SSB. The crystallinity of treated SSB was higher than that of untreated samples. The Gaussian function gave more accuracy for crystallinity determination (indicated by an R 2 value that was relatively higher than the Lorentzian function). It is consistent with Raman spectra in this study, which showed a specific band at 370–380 and ~ 1090 cm−1 from cellulose. The higher carbohydrate content of SSB pulp showed that the delignification process using kraft pulping with a variation of alkali active and sulfidity loading could be an alternative method to cellulose recovery for cellulose-derived products.