Magnetic Chitosan-Glutaraldehyde/Zinc Oxide/Fe3O4 Nanocomposite: Optimization and Adsorptive Mechanism of Remazol Brilliant Blue R Dye Removal

A magnetic Schiff’s base chitosan-glutaraldehyde/Fe3O4 composite (CHT-GLA/ZnO/Fe3O4) was developed by incorporating zinc oxide (ZnO) nanoparticles into its structure to prepare an efficient adsorbent for the removal of remazol brilliant blue R (RBBR) dye. The CHT-GLA/ZnO/Fe3O4 was characterized by the following methods: CHN, BET, FTIR, XRD, SEM–EDX, pHpzc, and potentiometric titrations. Box-Behnken design based on response surface methodology was used to optimize the effects of the A: ZnO nanoparticles loading (0–50%), B: dose (0.02–0.1 g), C: pH (4–10), D: temperature (30–60 °C), and time E: (10–60 min) on the synthesis of the magnetic adsorbent and the RBBR dye adsorption. The experimental data of kinetics followed the pseudo-second order model, while isotherms showed better fit to Freundlich and Temkin models. The maximum adsorption capacity of the target nanocomposite (CHT-GLA/Fe3O4 containing 25% ZnO or CHT-GLA/ZnO/Fe3O4-25) was reached of 176.6 mg/g at 60 °C. The adsorption mechanism of RBBR onto CHT-GLA/ZnO/Fe3O4 nanocomposite can be attributed to multi-interactions including electrostatic attractions, hydrogen bonding, Yoshida H-bonding, and n-π interactions. This study offers a promising hybrid nanobiomaterial adsorbent in environmental nanotechnology to separate and remove the contaminants such as organic dyes from wastewater.