Novel adsorbent based on carbon-modified zirconia/spinel ferrite nanostructures: Evaluation for the removal of cobalt and europium radionuclides from aqueous solutions.

Herein, a novel adsorbent based on carbon-modified zirconia/spinel ferrite (C@ ZrO2/Mn0.5Mg0.25Zn0.25Fe2O4) nanostructures were chemically prepared to remove 60Co and 152+154Eu radionuclides from liquid media using batch experiments. The XRD pattern confirms the successful preparation of the C@ZrO2/MnMgZnFe2O4 composite. Also, SEM and TEM images confirmed that the composite owns a heterogeneous morphology in the nanoscale range. The optical band gap value of Mn0.5Mg0.25Zn0.25Fe2O4, ZrO2, and the composite samples was 1.45, 2.38, and 1.54 eV, respectively. Many parameters have been studied as the effect of time, solution pH, and initial ion concentration. The kinetics models for the removal process of 152+154Eu and 60Co radionuclides were studied. The second-order kinetic equation could describe the sorption kinetics for both radionuclides. The Langmuir monolayer capacity for 60Co was 82.51 mg/g and for 152+154Eu was 136.98 mg/g. The thermodynamic parameters such as free energy ΔGo, the enthalpy ΔHo, and the entropy ΔSo were calculated. The results indicated that the sorption process has endothermic nature for both two radionuclides onto C@ZrO2/MnMgZnFe2O4 composite.

Antibacterial, antibiofilm, and photocatalytic activities of metals-substituted spinel cobalt ferrite nanoparticles.

This study reports the photocatalytic degradation of Methylene Blue (MB) dye (a class of dyestuffs that are resistant to biodegradation) under the influence of UV-light irradiation. Antibacterial and antibiofilm activities of ferrite nanoparticles (FO NPs) were examined against some pathogenic bacteria isolated from the medical operating room surfaces. In the same context, metals-substituted spinel cobalt ferrite nanoparticles with nominal composition [MxCo1-xFe2O4 NPs; (M = Zn, Cu, Mn; x = 0.0, 0.25, 0.5 and 0.75)] were synthesized by citrate sol-gel method. Also, the structures of the synthesized FO NPs were characterized by X-ray diffraction, and Williamson-Hall (WH) method was used to determine the crystallite size. The estimated specific surface area is found in the range from 37.99 to 107.05 m2/g, between the synthesized ferrites, Zn0.5Co0.5Fe2O4 NPs have average pore radius 1.84 nm and the pore volume was 0.136 ml/g. SEM images revealed that, the synthesized FO NPs have an unique pores and uniformly distribution, while EDX spectra shows the elemental composition for the synthesized FO NPs. The elastic properties of FO NPs have been estimated using FTIR data, whereas (M - H) hysteresis loops revealed that, by replacing cobalt ions with Zn, Cu, and Mn ions the magnetic behaviour changed from ferromagnetic to paramagnetic. Results obtained from the photocatalysis indicated that Mn0.75Co0.25Fe2O4 NPs (30.0 mg) were a promising photocatalyst achieving 96.0% removal of MB after 100 min of UV-light exposure in the alkaline solution. Antibacterial results showed that the most effective combination was Zn0.75Co0.25Fe2O4 NPs (20.0 ppm) displaying activity against Staphylococcus aureus, Enterococcus columbae, and Aerococcus viridians by 15.0, 13.0, and 12.0 mm ZOI, respectively. Additionally, Zn0.75Co0.25Fe2O4 NPs were active as antibiofilm factors producing activity by 63.7, 57.9, and 45.5% towards S. aureus, A. viridians, and E. columbae, respectively. Accordingly, Zn0.75Co0.25Fe2O4 and Mn0.75Co0.25Fe2O4 NPs can be utilized in industrial, biological and medical applications.