Magnetic separation, sunlight-driven photocatalytic activity, and antibacterial studies of Sm-doped Co0.33Mg0.33Ni0.33Fe2O4 nanoparticles.

Magnetic nanoparticles have emerged as a promising tool for wastewater treatment due to their unique properties. In this regard, Co0.33Mg0.33Ni0.33SmxFe2-xO4 (0.00 ≤ x ≤ 0.08) nanoparticles were prepared to examine their magnetic separation efficiency (MSE), photocatalytic, antibacterial, and antibiofilm performances. Pure nanoparticles, having the highest saturation magnetization (Ms = 31.87 emu/g), exhibit the highest MSE, where 95.6% of nanoparticles were separated after 20 min of applying a magnetic field of 150 mT. The catalytic performance of the prepared samples is examined by the photodegradation of rhodamine B (RhB) dye exposed to direct sunlight radiation. Improved photocatalytic activity is exhibited by Co0.33Mg0.33Ni0.33Sm0.04Fe1.96O4 nanoparticles, labeled as Sm0.04, where the rate of the degradation reaction is enhanced by 4.1 times compared to pure nanoparticles. Rising the pH and reaction temperature improves the rate of the photodegradation reaction of RhB. The incorporation of 15 wt% reduced graphene oxide (rGO) with Sm0.04 enhanced the rate of the reaction by 1.7 and 2.4 times compared with pure Sm0.04 sample and rGO, respectively. The antibacterial and antibiofilm activities against Escherichia coli, Leclercia adecarboxylata, Staphylococcus aureus, and Enterococcus faecium are assessed by the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) broth microdilution, the agar well diffusion, the time-kill assays, the biofilm formation, and destruction assays. The bacteria used in these assessments are isolated from wastewater. The nanoparticles exhibit a bacteriostatic activity, with a better effect against the Gram-positive isolates. Co0.33Mg0.33Ni0.33SmxFe2O4 (x = 0.00) nanoparticles have the best effect. The effect is exerted after 2-3 h of incubation. Gram-positive biofilms are more sensitive to nanoparticles.

Influence of Ru doping on structural, optical, and photocatalytic properties of (Cd-Ni-Mn) nanoferrites.

This study reports the synthesis of (Cd0.4Ni0.4Mn0.2)Fe2-xRuxO4 nanoparticles (NPs), where x = 0.00, 0.005, 0.01, 0.015, 0.02, and 0.04, via co-precipitation method. The synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and photoluminescence (PL) spectroscopy. The results confirmed the purity of the samples with the presence of a very small fraction of the hematite phase. Pseudo-spherical morphology was recognized from TEM images. Then, the prepared samples were further used as effective photocatalysts for the degradation of nitrobenzene under UV irradiation to examine the effect of doping on the photocatalytic activity. Among the synthesized samples, (Cd0.4Ni0.4Mn0.2)Fe1.985Ru0.015O4 NPs exhibited superior photocatalytic activity. This result is in good agreement with photoluminescence (PL) analysis in which (Cd0.4Ni0.4Mn0.2)Fe1.985Ru0.015O4 NPs revealed the slowest recombination rate of the electron-hole pair. To further improve the photocatalytic performance, different weight % of graphene was incorporated with (Cd0.4Ni0.4Mn0.2)Fe1.985Ru0.015O4 NPs. Finally, 81.41% of nitrobenzene was degraded after 180 min in the presence of 5 wt% graphene/(Cd0.4Ni0.4Mn0.2)Fe1.985Ru0.015O4 nanocomposites, and the degradation rate constant was estimated as 8.4 × 10-3 min-1.

Enhanced adsorption performance of magnetic Ni0.5Zn0.5Fe2O4/Zn0.95Co0.05O nanocomposites for the removal of malachite green dye.

This investigation reports the synthesis and characterization of (1-x)Ni0.5Zn0.5Fe2O4/(x)Zn0.95Co0.05O nanocomposites, with 0.0 ≤ × ≤ 0.5. Fourier transform infrared (FTIR) and Raman spectroscopies confirmed the purity of the samples and the presence of bands corresponding to octahedral and tetrahedral iron occupancies for Ni0.5Zn0.5Fe2O4 nanoparticles. A shift in peak positions of these bands was detected upon the addition of Zn0.95Co0.05O nanoparticles. The magnetic properties of the nanocomposites were examined using Mössbauer spectrometry at both room temperature and 77 K. Room temperature analysis showed the existence of both ferromagnetic and superparamagnetic behaviors, while at 77 K, all nanocomposites showed ferromagnetic behavior. The adsorption performance of the nanocomposite on the removal of malachite green (MG) dye solution was investigated by varying the contact time, adsorbent concentration, and reaction temperature. The adsorption reaction followed the second-order kinetics and the sample with x = 0.3 showed the highest adsorption rate. The adsorption rate showed an increase with the increase in the reaction temperature. The adsorption isotherm was determined by applying different adsorption isotherms (Langmuir, Freundlich, and Temkin isotherms), and the results are well-fitted with the Langmuir theoretical model.