Hybrid Polymer Nanocomposite of Ionically Crosslinked Chitosan/Tin Oxide Nanoparticles for Eosin Y Dye Removal: Isotherm, Kinetic, and Adsorption Optimization

ABSTRACT The current work prepared an organic–inorganic polymer hybrid nanocomposite of ionically crosslinked chitosan‐oxalate/tin oxide nanoparticles (Chi‐OXA/SnO 2 ) for eosin Y (EoY) dye removal from water systems. The adsorption of EoY dye was examined in relation to three factors: A: Chi‐OXA/SnO 2 dose (0.02–0.08 g), B: pH (4–10), and C: time (10–30 min) using response surface methodology (RSM). The BET surface area of Chi‐OXA/SnO 2 was determined to be 35.10 m 2 /g, while its total pore volume and mean pore diameter were computed to be 0.0257 cm 3 /g and 2.94 nm, respectively. The mean crystallite size of 29.86 nm in the Chi‐OXA/SnO 2 nanocomposite indicates that it mostly displays polycrystalline characteristics. The pseudo‐first‐order kinetic and the Freundlich models accurately described EoY adsorption by Chi‐OXA/SnO 2 . The optimal conditions for maximum EoY removal (97.78%) were determined to be a pH of 4, a Chi‐OXA/SnO 2 dose of 0.056 g, and a contact time of 16.9 min. The maximum adsorption capacity of the Chi‐OXA/SnO 2 nanocomposite for EoY dye was 539.4 mg/g at 25°C. The adsorption mechanism involved n‐π stacking interactions, Yoshida hydrogen bonding, conventional hydrogen bonding, and electrostatic interactions. These findings demonstrate that the chitosan‐based nanocomposite holds significant potential for the effective removal of dyes from wastewater.