Synthesis of Chitosan-Derived Schiff Bases for Enhanced Antioxidant Activity and Dye Adsorption Capabilities

Chitosan, a natural polysaccharide derived from the exoskeletons of shrimp and crabs, has amino and hydroxyl groups that provide biocompatibility, biodegradability, and antioxidant activity. This study aimed to enhance these properties by preparing chitosan-based Schiff base derivatives (CSB) containing phenolic hydroxyl groups. The formation of CSB was confirmed through physical and chemical structure analysis, demonstrating enhanced antioxidant capabilities and dye adsorption. Using 2,2-diphenyl-1-picrylhydrazyl (DPPH), the antioxidant activity of CSB was evaluated, showing a radical scavenging activity of 97.85% at the highest concentration, compared to 42.54% for chitosan. This significant enhancement is attributed to the introduction of phenolic hydroxyl groups. CSB's adsorption capacity for cationic and anionic dyes was tested, revealing excellent performance for anionic dyes due to its Schiff base structure. Optimization of experimental conditions showed that the adsorption capacity for anionic dyes increased from 305 to 710 mg/g. The Langmuir isotherm indicated monolayer adsorption with a maximum capacity of 1282.60 mg/g, and the pseudo-second-order kinetics model suggested chemical adsorption. These findings confirm CSB's improved antioxidant properties, potentially useful in food preservation and packaging, and its excellent capability for adsorbing organic dyes, indicating potential application in pollutant removal. © 2024 Korean Technical Assoc. of the Pulp and Paper Industry. All rights reserved.