Development of chitosan films using lemon Juice and impact of bimetallic and trimetallic nanoparticles on their physical properties

Abstract

The global challenge of plastic pollution has driven the search for biodegradable and sustainable materials. This thesis explores the development of chitosan (CH) films, synthesized using a green chemical approach that employs lemon juice and lemon peel extract as natural alternatives to synthetic acids. The incorporation of nanoparticles, explicitly zinc ferrite (ZnFe₂O₄ NPs) and nickel zinc ferrite (NiZnFe₂O₄NPs), further manipulate the functional properties of the films, making them suitable for diverse applications. The ZnFe₂O₄ NPs, synthesized using lemon peel extract, presented a crystalline size of 16 nm and significantly improved the mechanical (TS) and barrier properties of 1.5% CH films. The TS of the films increased from 0.641 MPa for bare CH to 0.835 MPa with 2% ZnFe₂O₄ NPs, while puncture strength improved by 2.7 times. The water vapor permeability (WVP) decreased by 28%, establishing enhanced barrier properties. Conversely, NiZnFe₂O₄ NPs (crystalline size 29 nm), enhanced 2% CH film flexibility, achieving a 36.83% elongation at break with 2% NP reinforcement. These films also exhibited enhanced resistance to moisture, making them suitable for applications that require better barrier properties. Morphological testing, including SEM and AFM, revealed that NPs incorporation altered the surface texture of the films, increasing roughness uniformly with NP concentration. FTIR spectra confirmed successful NPs’ integration, with characteristic metal-oxygen bond vibrations appearing at specific wavenumbers. Optical properties showed minimal color changes after NPs addition, with both ZnFe₂O₄ and NiZnFe₂O₄ films maintaining suitable transparency for practical applications. This thesis highlights the potential of green-synthesized CH films as eco-friendly substitutes for conventional plastics. ZnFe₂O₄ films demonstrated superior mechanical strength and barrier properties, while NiZnFe₂O₄ films provided improved flexibility and moisture resistance. The integration of green chemistry with nanotechnology establishes a sustainable pathway for the development of highperformance polymeric materials, addressing pressing environmental and industrial needs.