11-08: Carboxymethylation of cellulose from sugarcane straw pretreated by steam explosion

The sugarcane processing generates various agricultural byproducts such as bagasse and straw, which is considered one of the main waste generated due to the mechanization of the harvest in Brazil. Thus, the availability and composition of sugarcane straw have driven a great effort to develop technologies that provide its effective utilization. In this scenario, this study aims to separate the main components of the straw to obtain cellulose to be turned into carboxymethyl cellulose (CMC). Sugarcane straw was pretreated by steam explosion, delignified, treated with xylanase and bleached with hydrogen peroxide. The cellulose obtained was subjected to an alkalinization stage and subsequent etherification with monochloroacetic acid to produce CMC.  Chemical characterization of the materials obtained during the process was carried out. SEM images of the fibers corroborate the results of chemical analysis, which showed a large solubility of components, making the fibers more exposed. The efficiency of procedures performed in the removal of lignin to obtain cellulose could be verified by the decrease in kappa number and, from results obtained by chemical characterization. The dissolution of the CMC in water and the FTIR spectra confirm the success in obtaining this material. The degree of substitution found for the cellulose derivative produced (0.48) was close to the degree of substitution of commercial cellulose (0.46). [Acknowledgments due to FAPESP, CNPq and CAPES]