Application of nanocrystalline spinel MFe2O4, (M=Co and Cu) in waste water treatment

Transition metal spinel ferrites MFe2O4 (M=Cu and Co) were successfully synthesized following the co-precipitation method and their structural, optical, photocatalytic, antimicrobial and toxicity properties were studied. The characterization of the title compounds has been carried out using XRD, SEM, EDS, FT-IR and UV-vis DRS spectroscopy. The XRD studies confirmed a cubic spinel structure with the Fd-3m space group, and CuFe2O4 and CoFe2O4 exist in the nanocrystalline size of 20 nm and 16 nm, respectively. The SEM images revealed the agglomerated nature of the ferrite nanoparticles, and the EDAX spectrum confirmed the samples elemental compositions and purity. The FT-IR spectra indicated the presence of metal-oxygen stretching bands. The ferrite samples demonstrated photocatalytic activity in the visible region, as assessed by methylene blue (MB) degradation in an aqueous solution under visible irradiation. After 105 min, CuFe2O4 and CoFe2O4 catalysts exhibited 72% and 56% degradation for the MB solution. Through broth dilution, MFe2O4 (M=Cu and Co) nanoparticles were evaluated for their antimicrobial activity using S. aureus and E. coli, a gram-positive and gram-negative bacterium, respectively. Studies indicated that CoFe2O4 nanoparticles exhibit better antibacterial activity when compared to CuFe2O4. However, the antifungal activity study indicated that CuFe2O4 nanoparticles exhibit better antifungal activity when compared to CoFe2O4 nanoparticles. The toxicity of the nanomaterials was tested by mixing MFe2O4 (M=Cu and Co) with normal fly food and administering it orally to Drosophila melanogaster. The results indicated that the functionalized CuFe2O4 nanoparticles are less toxic to living organisms. Hence, optimized nanocrystalline spinel has the potential to degrade dyes from polluted water and act as an antimicrobial agent by rupturing pathogen cells. They have potential applications in both environmental safety and biomedicine.