Natural chalcone dye-functionalized magnetite nanoparticles: Synthesis, characterizations and performance for the removal of methylene blue and the antibacterial activity

Abstract

In the present research work, we report the co-precipitation synthesis of size‐controlled of uncoated (Magn) and natural chalcone dye-functionalized superparamagnetic magnetite nanoparticles (Magn_NCD NPs) and the study of their efficiency for the adsorption of methylene blue (MB) as well as their antibacterial activity. The NCD was isolated from Acacia cyanophylla and characterized by using IR, UV–visible and 1H NMR spectroscopies. For the functionalized NPs, the size-control was achieved by varying the pH (pH5 for the sample Magn_NCD5 and pH8 for the sample Magn_NCD8) of the reaction medium. The powders consisted of almost spherical NPs with an average particle size of ∼8, ∼3 and ∼7 nm, for Magn, Magn_NCD5 and Magn_NCD8, respectively. Adsorption study of the MB onto the NPs was conducted by varying the NPs’ nature, the pH, the NPs’ dosage, the MB concentration and the contact time. Regarding the effect of the NPs’ nature on the removal of MB, the smallest NPs (Magn_NCD5) were noticeably more performant. For these NPs, the removal efficiency was found to increase with the increase of pH in the pH range 3–9. Additionally, the adsorption kinetics was studied by the three most applicable kinetic models. The pseudo-second order kinetic model was better suited to the experimental adsorption data. Moreover, the adsorption isotherms were analyzed using the Langmuir, Freundlich, Sips and Redlich–Peterson models. The experimental data were best fitted to the Sips model with an extremely high correlation coefficient. Based on this model, the maximum adsorption capacity was calculated (qm = 125 mg.g−1). The reusability of Magn_NCD5 was also tested. These NPs showed a good reusability; After 5 regeneration-reuse cycles, the decrease in MB removal % was less than 8%. Finally, the antimicrobial activity was carried out against P. aeruginosa (gram-negative) and E. faecalis (gram-positive) bacteria. The Magn_NCD5 showed more zone of inhibition in E. faecalis (19 mm) than P. aeruginosa (14 mm).