Synthesis of magnetic Fe3O4@SiO2 nanoparticles decorated with polyvinyl alcohol for Cu(II) and Cd(II) ions removal from aqueous solution

This work describes fabrication of Fe3O4@SiO2 core–shell nanoparticles functionalized with polyvinyl alcohol (PVA) and its application for the removal of Cu(П) and Cd(П) ions. Surface chemistry and morphology during functionalization of Fe3O4@SiO2 NPs were evaluated utilizing Fourier transform infrared spectroscopy, X-ray diffraction, energy-dispersive X-ray analysis, vibration sample magnetometer, transmission electron microscope, field emission scanning electron microscope, and dynamic light scattering. The performance of the PVA-modified magnetic nanoparticles for Cu(П) and Cd(П) ions removal was evaluated by changing five process variables: contact time of adsorbent, temperature, pH, adsorbent dosage, and initial concentration. The highest removal efficiency was observed at a pH value of 7, an adsorbent dose of 15 mg, an initial concentration of 0.5 mmol/L, and a contact time of 25 min for Cu(II), while these values are 7, 15 mg, 0.4 mmol/L, and 20 min for Cd(II), respectively. The adsorption equilibrium is well explained by Langmuir adsorption isotherms which namely monolayer adsorption. The adsorption isotherm studies of the novel adsorbent in removing target ions from wastewater showed that the maximum adsorption amounts of Cu(П) and Cd(П) were 1.57 and 0.99 mmol/g at 35 °C. According to the calculated parameters and fitting model, the kinetics adsorption data are well fitted to the pseudo-second-order kinetic model which suggests that the main rate-determining step was chemisorption's. According to the results, the prepared composite possesses excellent adsorption efficiency to be applied for the preconcentration of target heavy metal ions in the field of water treatment. The new adsorbent is completely separated from the aqueous solution under external magnetic field for five consecutive cycles without significant loss of activity.