A Comparative Study of Different Methods for Cellulose Extraction from Lignocellulosic Wastes and Conversion into Carboxymethyl Cellulose

Abstract

AbstractCarboxymethyl cellulose (CMC) is an appealing industrial chemical obtained by modification of cellulose with redundant applications in food, pharmaceuticals, paints, detergents and others. This report demonstrates the comparative study of potential of different lignocellulosic biomass by using five traditional methods to get white, pristine cellulose with higher percentage yield from waste, later, conversion of cellulose into its derivative i. e., carboxymethyl cellulose (CMC). Four raw materials comprising of wheat straw, sugarcane bagasse, rice straw and banana leaves were employed as an alternating source of cellulose. Sulfide method came out as a most viable delignification method, used to degrade all dewaxed wastes, efficiently. After cellulose extraction, substitution of hydroxyl groups of cellulose was executed by infusing cellulose with sodium hydroxide (NaOH) and monochloroacetic acid (MCA) in the presence of isopropanol as supporting medium. In this way, a variety of cellulose and CMC were obtained and verified with commercial samples of both products. Furthermore, characteristics of different CMC were checked including degree of substitution (DS), CMC content, moisture content, solubility and purity. The CMC from wheat straw showed the highest DS (2.1), solubility and yield. FTIR spectra confirmed the replacement of hydroxyl group with carboxymethyl group by indicating characteristic peak of carbonyl group (‐CO) at 1588 cm−1. In 1H NMR spectrum, plethora of peaks in the region 3–5 ppm indicated the derivatization of cellulose and 13C NMR confirmed the peaks of carbonyl carbons at 180 and 182 ppm. X‐ray diffraction (XRD) shows that the crystallinity of CMC has been reduced, significantly.