Effect of Gd3+-, Pr3+- or Sm3+-substituted cobalt–zinc ferrite on photodegradation of methyl orange and cytotoxicity tests

Abstract

Gd3+-, Pr3+- or Sm3+-doped Co-Zn (Co0.5Zn0.5Fe2O4) magnetic ferrites (i.e., Co0.5Zn0.5Gd0.1Fe1.9O4, Co0.5Zn0.5Pr0.1Fe1.9O4 and Co0.5Zn0.5Sm0.1Fe1.9O4) were prepared using a facile sol-gel approach, and the structure, surface morphology and chemical composition of the products were studied by means of scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD), UV-visible diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, Fourier transform infrared spectroscopy (FT-IR) and vibrating sample magnetometer (VSM) spectroscopy. XRD patterns show the Co-Zn product is composed of cubic spinel phases with few impurities or secondary phases, and the average crystallite sizes of the samples are determined to be approximately ∼51–80, ∼99–181, ∼68–103 and ∼83–133 nm. Also the coercivity and remnant and saturation magnetizations, evaluated by vibrating sample magnetometer (VSM), are found to increase linearly with the incorporation of Gd3+, Pr3+ and Sm3+ in the product formulation. The Co1−xZnxFe2−yRyO4 photocatalyst sample is found to display a red shift in its absorption, and exhibits outstanding photocatalytic effects in the degradation of MO under ultraviolet (UV) light. This is attributed to the reduction of the band gap of cobalt-zinc ferrite due to the presence of rare earth ions. Further in vitro evaluations of the cytotoxic effects of the synthesized nanoparticles were performed on a HeLa cell line.