Manufacturing of nanocrystalline cellulose

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Kemian tekniikan korkeakoulu | Master's thesis
Biomass refining
Degree programme
Master's Programme in Chemical, Biochemical and Materials Engineering
Nanocrystalline cellulose (CNC) has attracted considerable attention over the last several decades in many fields. Sulfuric acid hydrolysis is utilized as the state-of-the-art for producing nanocrystalline cellulose nowadays. The common conditions of H2SO4 standard method used 1 735% of acid dosage, 64% of acid concentration, 45oC of temperature and 45 minutes of reaction time. The purpose of this thesis is to develop and determine a novel modified manufacturing method for CNC production process by adjusting the reaction circumstances. More precisely, this study investigates the possibility for using lower acid amount and higher temperature (65oC-85oC) to produce nanocrystalline cellulose. The raw material in the production procedures was microcrystalline cellulose (MCC). CNCs were extracted from MCC by sulfuric acid. Various reaction conditions (acid dosage, temperature, acid concentration, reaction time) were changed based on the performance of CNC yield and quality in order to obtain the optimal circumstances. The morphology and dimensions of CNCs were investigated by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The chemical structure and crystallinity were measured by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Thermogravimetric analysis (TGA) was utilized to study the thermal stability of CNCs. The results from the characterization methods demonstrated that using lower sulfuric acid dosage and higher temperature could also produce CNCs with promising yield and qualities as standard method. The optimal hydrolysis conditions for modified method are described as follow: 700% of acid dosage, 65oC of temperature, 63% of acid concentration and 20 minutes of reaction time. Based on the modified method, CNCs could have a maximum yield of 30.6% of and crystallinity of 79.3%. The average length of CNCs could be 183.1nm and the mean diameter was 7.6nm. The preliminary economy analysis illustrated that applying modified method provided better economy than the existing standard method.
Dahl, Olli
Thesis advisor
Vanhatalo, Kari
nanocrystalline cellulose, sulfuric acid hydrolysis, reaction circumstances, yield, dimensions, crystallinity
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