Response Surface Methodology Modeling, Experimental Validation, and Optimization of Acid Hydrolysis Process Parameters for Nanocellulose Extraction

Abstract

Nanocellulose is one of the most significant nanomaterials that can be derived from lignocellulosic materials. The properties of nanocellulose make it a promising material for a variety of applications, including paper and paperboard production, antibacterial agents, coatings, cosmetics, drug delivery, soft tissue transplant, blood vessel replacements, and others. This study focuses on the extraction of nanocellulose from teff straw, which is an agricultural residue and locally available in Ethiopia. Nanocellulose was extracted by acid-chlorite delignification, alkali, and acid hydrolysis method. The effect of acid hydrolysis process parameters, sulfuric acid concentration, time, and the temperature was studied using response surface methodology. The central composite design was used to screen and adjust the design matrix with three factors and five levels. The optimum yield was 62.2% when acid concentration, time, and temperature were 44.4%v/v, 32 min, and 40.5 ° C respectively. The Analysis of variance (ANOVA) was carried out to identify the most significant factors that influence the percentage of nanocellulose yield. The Fourier-transform infrared (FTIR) result confirms the reduction and total removal of lignin, and the amorphous parts in straw. The average particle size determined by dynamic light scattering (DLS) was 101.6 nm with a polydispersity index of 0.047. From the X-ray diffractometer (XRD) result crystallinity index of straw and nano-cellulose was 47.7% and 77.1% respectively. The thermogravimetry analysis demonstrates the maximum temperature of nanocellulose and cellulose was 270 °C and 360 °C respectively. The Scanning electron microscopy (SEM) result implies the surface of nano-cellulose was improved by the chemical treatments.