Multifunctional PANI-Chitosan-ZnO nanocomposites with enhanced anticorrosive, antibacterial, optical, magnetic, and photocatalytic approach

Incorporating synthetic and natural polymers with metal oxide nanoparticles (NPs) can significantly alter electrical, optical, catalytic, antibacterial, mechanical, physical, and magnetic properties. In this study, nanocomposites (NCs) containing polyaniline (PANI), a conducting polymer, Chitosan (CS), a natural polymer, and ZnO metal NPs were synthesized using in situ chemical oxidative polymerisation technique. The multifunctional properties of these NCs, including antibacterial, photocatalytic, anticorrosive, and magnetic, were investigated. The photocatalytic degradation efficiency of methylene blue dye (MBD) was evaluated under UV and sunlight and found to be higher in sunlight. The MBD degradation efficiency reached 74.57% in 6.4 h in UV light and 89.62% in 5.0 h in sunlight. The synthesized NCs exhibited a ‘magnetic susceptibility’ (χ) of 0.035, indicating paramagnetic behavior. The optical band gap of the NCs was 2.9 eV, lower than that of pure PANI (3.8 eV) and ZnO NPs (3.35 eV). The zone of inhibition (14.0 mm) was measured against S. aureus (Gram-positive) bacteria at a concentration of 4.5 mg/mL. The NCs demonstrated anticorrosive activity against mild steel in 1.0 M H 2 SO 4 , achieving an inhibition efficiency of 90.34% at 10 ppm. This study leads to the development of NCs with significant potential for water purification, environmental remediation, anticorrosive coatings, and applications requiring conductive and magnetic properties.