Magnetic hyperthermia and photocatalytic degradation of rhodamine B dye using Zn-doped spinel Fe3O4 nanoparticles

A wide range of magnetic spinel ferrite nanoparticles is extensively studied to understand their electrical, magnetic and catalytic properties and use them in a suitable application. ZnFe2O4 nanoparticles are good photocatalysts and Fe3O4 nanoparticles are good superparamagnetic hyperthermia material. However, both the properties strongly depend on chemical composition and particle size, and size distribution. In order to study the chemical composition and particle size distribution on the above properties, narrow size distributed ZnxFe3-xO4 (x = 0.1, 0.3 and 0.5) nanoparticles were synthesized by the solvothermal reflux method. X-ray diffraction and electron diffraction profiles and infrared spectra confirmed the formation of well-crystallined compounds in cubic spinel lattice. Transmission electron micrographs show that the samples are around 10 nm in diameter. Magnetic hysteresis loops data show that all the samples are superparamagnetic at room temperature with negligible coercivity. The maximum magnetization varies with Zn concentration due to the distribution of metal cations among tetrahedral and octahedral sublattice based on their crystal field stabilization energy values. Superparamagnetic hyperthermia properties of aqueous nanoparticles colloids of all the samples were studied by the calorimetric method under biocompatible alternate magnetic field frequency (316 kHz) and amplitude (35.28 kAm(-1)). All the samples showed a superior specific heat generation rate (SHR) or specific energy absorption rate (SAR) under the above field parameters. The x = 0.5 sample has shown a high SHR value of 138.22 Wg(-1). Further, the photocatalytic properties of all the samples were studied through rhodamine B dye degradation under UV light. All the samples were shown dye degradation efficiency of 97% in 300-min reaction period. The synthesized samples may be used in superparamagnetic hyperthermia therapy for cancer treatment and industrial effluent treatment in the tannery and textile industries. It is concluded that a small concentration change in Zn does not produce an appreciable change in superparamagnetic hyperthermia and photocatalytic properties of Fe3O4, though there are noticeable changes in the above properties with Zn concentration.