Synthesis and Characterization of Cellulose Acetate from Khat (<i>Catha edulis</i>) Waste

Abstract

Agro-industries produce a lot of lignocellulosic waste, and using this cellulose-rich waste can help with both ecological and economic issues. In this study, cellulose fibers were isolated from a locally abundant source of khat waste and homogeneously acetylated to produce cellulose acetate. In order to determine their yield, chemical functionality, crystallinity, shape, and thermal stability, the as-obtained cellulose fibers and cellulose acetate were analyzed. Cellulose content on a dry weight basis was found to be about 40% in untreated khat waste and about 90% in as-obtained cellulose fibers. The degree of substitution of cellulose acetate ranged from 1.4 to 2.1 with weight gains from 133 to 146% (w/w). SEM images indicated that the asobtained cellulose existed as a fibrous and elongated structure while the cellulose acetate was granular. The FTIR results showed the removal of non-cellulosic materials during chemical treatments of khat waste. Furthermore, an effective attachment of acetate groups was confirmed by the appearance of new peaks around 1743 cm-1, 1368 cm-1, and 1221 cm-1 in the FTIR spectra of cellulose acetate. The elimination of noncellulosic components, notably hemicellulose and lignin, was demonstrated by an increase in the crystallinity index (CrI) of extracted cellulose (73%) after chemical treatment of untreated khat waste (56%). This index then reduced in the cellulose acetate following esterification. This study is beneficial for developing cellulose and cellulose acetate from khat waste as an alternative source for various potential value-added applications.