Influence of pH on structural, optical and magnetic properties of undoped and Ni-doped α-Fe2O3 nanoparticles for antimicrobial activity

Abstract

In this present study, the magnetic and antimicrobial properties of biosynthesized α-Fe2O3 and Ni doped α-Fe2O3 nanoparticles were synthesized from ferric chloride and nickel chloride with the addition of Catharanthus roseus flower extract for different sodium hydroxide concentrations to maintain the pH as 5, 7 and 12. The influence of pH indicates changes observed in the size, structure and crystallinity of the prepared samples. The synthesized nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), UV visible spectroscopy (UV-Vis) and vibrating sample magnetometry (VSM), and their antimicrobial and antioxidant properties were investigated. The XRD analysis revealed the prepared nanoparticles have a rhombohedral hematite structure. FTIR analysis in the range 4000 to 400 cm−1 confirmed the presence of various functional groups for the prepared nanoparticles. The surface morphology and as well as structures of the prepared nanoparticles were confirmed by FESEM. The UV–Vis analysis showed the band gap energies of undoped and Ni-doped α-Fe2O3 nanoparticles. Furthermore, the VSM analysis showed the magnetic properties of undoped and Ni-doped α-Fe2O3 nanoparticles, exhibiting ferromagnetic behaviour at room temperature. The total reducing power of the as-prepared Ni doped α-Fe2O3 nanoparticles was maximum for pH 7, while the antioxidant property was lowered for the remaining samples.The inhibition zone of the prepared nanoparticles showed good antimicrobial activity for pH 7 and showed less inhibition for the other samples against Escherichia coli and Staphylococcus aureus.