Nanoparticle-loaded polyaniline-chitosan composites for efficient removal of rose bengal: Synthesis, characterization and adsorption performance

This study introduces a novel polyaniline–chitosan/nano TiO 2 composite (PAn-CS) synthesized through nanoparticle-incorporating to modify surface features, thereby improving its ability to adsorb and remove anionic rose Bengal (RB) dye. The composite was produced by incorporating TiO 2 , SiO 2 , or ZrO 2 nanoparticles into the PAn-CS composite using chemical oxidation via a single-stage precipitation procedure. Analysis of the structural and morphological characteristics was carried out with X-ray diffraction, Fourier-transform infrared and scanning electron microscopy. The composites’ thermal stability, surface properties, and surface charge of composites were also evaluated. The adsorption process was investigated through kinetics, isotherms, thermodynamics, and mechanistic insights. Results indicated that adding nano-oxides enhanced the PAn-CS composite’s affinity for RB removal. Optimal TiO 2 -content at 10% wt. howed a maximum adsorption efficiency of 96% within 60 minutes at 25 o C and pH 4, with a 0.025 g adsorbent dose and an initial dye concentration of 25 mg/L. Notably, the PAn-CS/TiO 2 composite demonstrated the highest RB adsorption capacity of 643.62 mgg -1 . The adsorption data were well fitted by the pseudo-second-order kinetic model, suggesting chemisorptions as the primary mechanism. The adsorption involved electrostatic, hydrogen bonds, and π-π interactions. The composite also showed excellent stability and reusability over five cycles, highlighting its potential for practical and sustainable dye-removal applications.