Quercetin‐Crosslinked Polyvinyl Alcohol Thin Films for Selective Adsorption of Cationic Dyes

ABSTRACT

Natural product, quercetin was employed as a physical crosslinker to develop polyvinyl alcohol (PVA) films (5, 10, and 20 wt%) via a facile solution casting method. The incorporation of quercetin evidently altered the physicochemical profile of the films, imparting higher water absorption capacity around 60%–77%, improved flexibility, and reduced stiffness compared to pure PVA. Among the series, PQ‐10 emerged as the most effective polymer for the removal of cationic dyes, displaying a remarkable 98.4% removal of methylene blue. It also exhibited selective adsorption of cationic dyes in the mixed dye systems. Adsorption was found to be pH‐ and temperature‐dependent, following pseudo‐first‐order kinetics with an equilibrium adsorption capacity Q _e (0.9755 mg/g) and fitting both Langmuir and Freundlich isotherm models with R ²  = 0.9996 and 0.9997, respectively, consistent with an endothermic electrostatic interaction mechanism. PQ‐10 exhibited pronounced antioxidant activity in the DPPH assay (IC₅₀~200 μg/mL), whereas ABTS and total antioxidant responses were weaker. Further, PQ‐10 exhibited negligible antibacterial and limited antifungal activity. Collectively, the multifunctional profile of PQ‐10 indicates its potential use as a sustainable material for wastewater treatment.