Studies on the efficient dual performance of Mn_1-xNi_xFe₂O₄ spinel nanoparticles in photodegradation and antibacterial activity

The present work describes the successful synthesize of spinel magnetic ferrite Mn_1-xNi_xFe₂O₄ (x=0.0, 0.1, 0.2, 0.3, 0.4 & 0.5) nanoparticles via a simple microwave combustion method which was then evaluated for its photocatalytic activity in the degradation of indigo carmine (IC) synthetic dye, a major water pollutant. Our results reveal that the synthesized of Ni²⁺ doped MnFe₂O₄ nanoparticles possess well-crystalline pure cubic spinel phase, exhibit excellent optical and magnetic properties. Further, the photocatalytic performance of the synthesized nanoparticles at different concentration ratios of Ni²⁺ ions was monitored by photocatalytic degradation of indigo carmine synthetic dye under UV (λ=365nm) light irradiation. In order to get maximum photocatalytic degradation (PCD) efficiency, we have optimized various parameters, which include catalyst dosage, initial dye concentration, pH and Ni²⁺ dopant content. It was found that the reaction was facilitated with optimum catalyst dose of 50mg/100mL, high dye concentrations of 150mg/L and acidic pH and among all the synthesized samples, Mn_0·5Ni_0.5Fe₂O₄ exhibit superior performance of photocatalytic activity on the degradation of indigo carmine synthetic dye. These results highlighted the potential use of effective, low-cost and easily available photocatalysts for the promotion of wastewater treatment and environmental remediation. In addition, the antibacterial activity of spinel magnetic Mn_1-xNi_xFe₂O₄ nanoparticles against two Gram positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram negative bacteria (Pseudomonas aeruginosa and Escherichia coli) was also examined. Our antibacterial activity results are comparable with the results obtained using the antibiotic, streptomycin.