Eco-Friendly Synthesis of Superparamagnetic Fe3O4 Nanoparticles from Hibiscus Rosa-Sinensis Leaf Extract and Their Application in RB-4 Dye Removal

In this study, iron-based nanoparticles (HS-Fe-NPs) were synthesized using an extract obtained from Hibiscus rosa-sinensis leaves. These nanoparticles were used to remove reactive blue-4 dye from synthetic water samples. The results indicated that a remarkable removal efficiency of over 99.50 percent was achieved for the reactive blue-4 dye with an initial concentration of 100 mg/L at pH 6.0. SEM, XRD, and FTIR analyses were conducted to understand the removal mechanism better and examine the surface changes of HS-Fe-NPs before and after adsorption. Furthermore, UV-VIS analysis was employed to determine the intermediate and final products of the reactive blue-4 dye, shedding light on the potential pathway. VSM analysis was performed to study the magnetic behavior of the synthesized nanoparticles, revealing their superparamagnetic nature with a saturation magnetization of 80.58 emu/g. The Freundlich model successfully described the sorption isotherm, indicating a favorable result based on the experimental data. The highest adsorption capacity of HS-Fe-NPs for RB-4 dye was determined to be 819.67 mg/g. The experimental results revealed that the pseudo-second-order model provided a more accurate representation of enhanced effectiveness. Furthermore, the ∆G° values were found to be negative at all temperatures, indicating the favorable and spontaneous characteristic of the sorption process.