FABRICATION CORN COB-BASED CELLULOSE HYDROGEL USING THE FREEZE-THAW METHOD AND CHARACTERIZATION PHYSICOCHEMICAL PROPERTIES AND ANTIBACTERIAL ACTIVITY

• Main Author: Rodhiyah, Marathur
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/79615
• Institution: Institut Teknologi Bandung

Indonesia is one of the largest corn producers in the world, with a corn production of 21.441.943 tons. Out of the total corn waste, corn cobs contribute at least 20% of the total waste. Corn cobs have several components, namely lignin (15.08%), cellulose (34.33%), and hemicellulose (20.17%). The cellulose content has the potential to be reused as a biodegradable material. Cellulose is an abundant natural polymer that is biocompatible, environmentally friendly, easily degradable, and contains many hydroxyl groups that allow it to interact with water molecules through hydrogen bonding, making it suitable for encapsulation in hydrogels. A hydrogel is a three-dimensional network structure made from a polymer that can absorb water. Cellulose is extracted from corn cobs through delignification, bleaching, and acid hydrolysis processes. The produced cellulose content reached 70.43%. Cellulose was transformed into a hydrogel using the freeze-thaw method to establish a stable and non-toxic hydrogel structure. In this study, the impact of adding NaOH concentrations of 2%, 3%, 4%, 5%, 6%, and 7% was identified to examine the physicochemical characteristics of cellulose hydrogels. SEM-EDS images revealed that cellulose powder had purer elemental content compared to corn cob powder. The hydrogel with a 3% NaOH concentration exhibited abundant cross-linking and the largest pore size. Additionally, at this concentration, the hydrogel achieved the highest degree of expansion at 48 hours, measuring 524,77 ± 8,56 %, with superior compressive and tensile strengths. As the NaOH concentration increased, the hydrogel experienced greater weight loss, indicating a decline in integrity. FTIR analysis showed the absence of hemicellulose and lignin groups, confirming the formation of cellulose groups in the hydrogel. XRD results indicated semicrystalline properties in cellulose powder with a crystallinity degree of 61.48%, while cellulose hydrogel exhibited an amorphous structure. TGA testing demonstrated that low NaOH concentration in cellulose hydrogel resulted in better thermal stability compared to cellulose powder due to cross-linking effects. Higher NaOH concentrations led to increased residue at 600°C, attributed to the substantial residue of NaOH itself. DSC findings revealed the melting point and heat required to break bonds, with cellulose powder having a melting heat of 383.75 J/g. In contrast, cellulose hydrogel exhibited significantly lower heat due to its amorphous structure. Antibacterial tests indicated that cellulose powder inhibited the growth of Staphylococcus aureus and Pseudomonas aeruginosa by 24.67% and 4.32%, respectively. Cellulose hydrogel, with its NaOH solvent, demonstrated bactericidal activity. Cytotoxicity tests revealed an IC50 > 900 µg/mL for all hydrogels, confirming their nontoxic and biocompatible nature towards normal cells. However, the use of NaOH on the body should not exceed 4% as it may cause irritation. Therefore, the safe hydrogel formulations for use are hydrogel with concentration of NaOH 2% and 3%.