Freeze-drying synthesis of mesoporous magnetic grafted chitosan/calcium oxide nanoparticle for remazol brilliant blue...

Herein, a mesoporous magnetic chitosan-salicylaldehyde/calcium oxide nanoparticle (CS-SL/CaO/Fe₃O₄) biocomposite adsorbent that was prepared via freeze-drying. The CS-SL/CaO/Fe₃O₄ was utilized for the adsorption of ramazol brilliant blue (RBB) dye from aqueous solution. The physicochemical properties of the CS-SL/CaO/Fe₃O₄ were evaluated using diverse characterization techniques, including BET, XRD, FTIR, FESEM-EDX, CHNS, and pH_pzc. The three main factors for adsorption included the following A: CS-SL/CaO/Fe₃O₄ dosage (0.02-0.1 g/100 mL), B: pH (4-10), and C: Time (60-540 min). These factors were improved using statistical methods, specifically the Box-Behnken design (BBD). The optimal conditions for achieving maximum RBB removal (62.5 %) are listed: CS-SL/CaO/Fe₃O₄ dosage of 0.1 g/100 mL, a solution pH of 7, and a contact time of 540 min. The adsorption kinetics and equilibrium isotherms were well described by the pseudo first order (PFO) kinetic and Langmuir isotherm models, respectively. Thus, the CS-SL/CaO/Fe₃O₄ material has a maximum adsorption capacity (q_max) of 63.3 mg/g for RBB at 25 °C. The adsorption mechanism of RBB onto the CS-SL/CaO/Fe₃O₄ surface was attributed to electrostatic forces, n-π stacking, H-bonding, and Pi-Pi interactions. Thus, CS-SL/CaO/Fe₃O₄ represents a recoverable magnetic adsorbent with potential for capture of organic dyes from wastewater.