Low-cost carboxymethyl holocellulose and carboxymethyl cellulose from wheat straw

Abstract

The chemical composition of Tunisian wheat straw was determined, demonstrating that this biomass is rich in αcellulose and holocellulose with values of 41.4% and 72%, respectively. Holocellulose and cellulose were extracted from this biomass and converted into carboxymethyl holocellulose (CMH) and carboxymethyl cellulose (CMC), respectively, with different degrees of substitution (DS) by varying the concentration of the etherifying agent. The physicochemical properties and the morphology of the different products synthesized were studied using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. The rheological behavior of all the CMH and CMC samples was also considered and the effect of the DS on the apparent viscosity of the materials obtained was studied. The results demonstrated that all the carboxymethylated products exhibited non-Newtonian thixotropic behavior and that the apparent viscosity of the aqueous solutions of CMH and CMH depended on the DS. We concluded that CMH and CMC with appropriate degrees of substitution have great potential for many applications.