Extraction And Characterization Of Cellulose Nanocrystals From Two Local Plant Materials

Abstract

Cellulose is a linear homopolysaccharide of repeating D-glucopyranose units which form about 15 – 20 % of the dry weight of plant biomass. It is the world’s most abundant renewable natural polymer with unique properties such as high strength, biocompatibility, low density and excellent mechanical properties. These excellent characteristics of the isolated cellulose nanocrystals coupled with their wide availability enable their potential application in areas of packaging materials to replace fossil-fuel based materials, in optical sensors, paints, and as reinforcements in composite materials. In this work, cellulose nanocrystals were isolated from two local plant biomass, Acasia sp. (sawie), and Palmae sp. (keteku), through a series of acid and alkaline hydrolysis to get rid of lignin, hemicellulose and other impurities, leaving crystalline cellulose nanocrystals. Cellulose nanocrystals were characterized by Fourier Transform Infra-Red (FT-IR) Spectroscopy, Optical Microscopy, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Thermogravimetric Analysis (TGA). SEM morphological analysis showed slender nanosize particles of CNCs of approximately less than 10 μm. FTIR analysis confirmed a removal of lignin and hemicellulose due to the disappearance of peaks at 1230 cm-1 (C – O bending) and 1765 – 1715 cm-1 (C = O stretching of aldehyde) respectively. Peak at 1160 cm-1 showed the presence of sulphonated groups which was evidenced by the uniform dispersibility of CNCs in solution due to the repulsive forces. The crystallinity index at 2Ꝋ (18o – 25o) was approximately -163.04 % for acacia sp. and -5460 % for palmae sp. Thermogravimetric analysis of both acacia sp. and palmae sp. showed high thermal stability of approximately 363.8 oC and 336.3 oC respectively. The characterized CNCs generally exhibited outstanding properties of high crystallinity, thermal stability and tunable surfaces enabling even dispersion in aqueous solution. Cellulose is a linear homopolysaccharide of repeating D-glucopyranose units which form about 15 – 20 % of the dry weight of plant biomass. It is the world’s most abundant renewable natural polymer with unique properties such as high strength, biocompatibility, low density and excellent mechanical properties. These excellent characteristics of the isolated cellulose nanocrystals coupled with their wide availability enable their potential application in areas of packaging materials to replace fossil-fuel based materials, in optical sensors, paints, and as reinforcements in composite materials. In this work, cellulose nanocrystals were isolated from two local plant biomass, Acasia sp. (sawie), and Palmae sp. (keteku), through a series of acid and alkaline hydrolysis to get rid of lignin, hemicellulose and other impurities, leaving crystalline cellulose nanocrystals. Cellulose nanocrystals were characterized by Fourier Transform Infra-Red (FT-IR) Spectroscopy, Optical Microscopy, Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Thermogravimetric Analysis (TGA). SEM morphological analysis showed slender nanosize particles of CNCs of approximately less than 10 μm. FTIR analysis confirmed a removal of lignin and hemicellulose due to the disappearance of peaks at 1230 cm-1 (C – O bending) and 1765 – 1715 cm-1 (C = O stretching of aldehyde) respectively. Peak at 1160 cm-1 showed the presence of sulphonated groups which was evidenced by the uniform dispersibility of CNCs in solution due to the repulsive forces. The crystallinity index at 2Ꝋ (18o – 25o) was approximately -163.04 % for acacia sp. and -5460 % for palmae sp. Thermogravimetric analysis of both acacia sp. and palmae sp. showed high thermal stability of approximately 363.8 oC and 336.3 oC respectively. The characterized CNCs generally exhibited outstanding properties of high crystallinity, thermal stability and tunable surfaces enabling even dispersion in aqueous solution.