Characterization of carboxymethyl microcrystalline cellulose derived from sustainable kenaf fiber

Abstract

Microcrystalline cellulose (MCC) extracted from kenaf fiber (KNF) was utilized as an alternative biomaterial for producing carboxymethyl microcrystalline cellulose (CMMCC). The well-known etherification of KNF using monochloroacetic acid, sodium, and hydroxide produced MCC. The yield of produced MCC was 32 %. In addition, high crystallinity index (92 %) and low degree of substitution was recorded compared to final product, i.e., CMMCC. Characterization of CMMCC, MCC, and KNF fibers were performed. FTIR analysis revealed a significant absorption peak at 1620.2 cm⁻¹, indicating vibrational stretch of carboxyl groups (COO−), and another peak at 1423.8 cm⁻¹ corresponding to salts of COO− in CMMCC. The XRD analysis revealed significant reduction in crystalline structure of CMMCC post-synthesis, characteristic peaks of native cellulose became nearly indistinguishable, indicating a transition to an amorphous form. SEM images displayed ruptured and deformed surface morphology of CMMCC powder, with visible cracks due to breakdown of polymer chains when treated with 40 % NaOH. EDX analysis confirmed cellulose in each fiber sample was highly pure because of chemical treatments. Furthermore, CMMCC powder demonstrated stable thermal behavior with high decomposition peak temperature analyzed using TGA and relatively uniform horizontal curve on DSC pattern. Thus, obtained CMMCC exhibits promise candidate in food additive and pharmaceutical industries.