Synthesis of carboxymethylcellulose from corn straw waste: comparison between pre-treatments with sodium hydroxide and low-cost ionic liquid

Abstract

© 2021, Iran Polymer and Petrochemical Institute.In this work, the possibility of using corn straw to obtain carboxymethylcellulose (CMC) was verified. However, to obtain CMC from lignocellulosic residues, it is necessary to carry out initial treatments to reduce the levels of lignin and hemicellulose. In this context, studies have been conducted to enable the use of an ionic liquid (IL). The n-butylammonium acetate was used to treat the straw instead of the pulping stage for the subsequent attainment of CMC. For comparison, we determined the composition of the resulting material after the stages of NaOH pulping (NaP) or treatment with the IL (at 80 °C—ILP80 and 120 °C—ILP120) and bleaching, to analyze the purity of the cellulose obtained. It was also possible to verify that the treatment at 120 °C was more effective to remove inorganic materials and lignin, leading to cellulose with 91.45 ± 0.11% purity when compared with its treatment at 80 °C. CMC was successfully synthesized and presented similar morphologies accordingly. Consequently, the attainment of CMC was confirmed by analyzing the data obtained via FTIR, NMR, and XRD techniques, as well as the analyses of degree of substitution. It was also possible to recover the ionic liquid at a purity of 95.93%. Graphical abstract: [Figure not available: see fulltext.]