Crosslinked Chitosan/Modified Pomegranate Peel Composite for Rhodamine B Dye Removal

ABSTRACT A sustainable biocomposite (chitosan‐oxalate/pomegranate peel‐H 2 SO 4 [CH‐OX/PP‐HS]) of crosslinked CH‐OX and treated pomegranate ( Punica granatum L.) peel was developed for high‐efficiency adsorption of rhodamine B (RhB) dye from water. Box–Behnken design (BBD) was implemented to examine the adsorption variables. Optimal conditions for RhB dye removal (78.41%) were achieved at pH ∼10, a CH‐OX/PP‐HS dose of 0.056 g, and 60 min contact time. Textural analysis revealed that CH‐OX/PP‐HS possesses a specific surface area of 13.85 m 2 /g, a pore volume of 0.0673 cm 3 /g, and an average pore width of 19.43 nm. Adsorption followed the Freundlich isotherm and pseudo‐first‐order kinetics. The CH‐OX/PP‐HS composite exhibited a maximal adsorption capacity of 174.5 mg/g. The production cost of CH‐OX/PP‐HS is approximately $173/kg. These findings support CH‐OX/PP‐HS as a sustainable and cost‐effective adsorbent for cationic dye removal, advancing green chemistry and water treatment strategies.