Improved Photocatalytic and Antibacterial Activity of Mg0.33Ni0.33Co0.33GdxFe2‐xO4 Nanoparticles Synthesized via the Co‐precipitation Method.

This study reports the synthesis of Mg0.33Ni0.33Co0.33GdxFe2‐xO4 nanoparticles (NPs) with 0.00≤x≤0.08 by the co‐precipitation method. The structural and optical properties of NPs are investigated. As Gd content increases, the lattice parameter and the bandgap energy increase whereas the particle size decreases. The photocatalytic performance of NPs is evaluated in the degradation of methyl violet (MV) dye under sunlight irradiation. The best activity is exhibited by Mg0.33Ni0.33Co0.33GdxFe2‐xO4 where x=0.04. The rate of the photodegradation reaction is boosted by increasing the pH and temperature. 95.4 % of MV is degraded after 240 min upon the addition of 5 wt. % carbon dot. The NPs are tested against Gram‐positive (Staphylococcus aureus and Enterococcus faecium) and Gram‐negative bacteria (Escherichia coli and Leclercia adecarboxylata) isolated from wastewater. The antibacterial activity was tested by the minimum inhibitory concentration and minimum bactericidal concentration broth microdilution assay, agar well diffusion assay and time‐kill test. The results show that the NPs exhibit inhibitory activity against Gram‐positive bacteria. Furthermore, NPs show bacteriostatic activity after 3 hours of incubation. The antibiofilm activity of the NPs is tested by the inhibition of biofilm formation and the destruction of pre‐formed biofilm assays. The results show an inhibitory activity of the NPs against Gram‐positive biofilms. [ABSTRACT FROM AUTHOR]