Eco-friendly synthesis of magnetic Fe3O4 and Zn-doped Fe3O4 nanoparticles for efficient catalytic degradation of Safranin dye as an organic pollutant

Safranin is an organic dye that is difficult to remove and is dangerous to the environment and human health, and thus effort to develop sustainable nanocatalysts to remove it is a pressing challenge. An environmentally friendly and sustainable pathway was taken in this study where Alstonia scholaris plant extract was used as a natural reductant to the synthesis of Fe 3 O 4 and Zn-doped Fe 3 O 4 nanoparticles. SEM, EDS, XRD, VSM and UV-Vis spectroscopy were used to characterize the nanoparticles, and the photocatalytic activity was determined by degrading safranin under sunlight by changing the pH, the catalyst amount, the concentration of the dye, and the time of contact, where the reaction was first-order. The catalyst had good reusability of four cycles. The Zn-doped Fe 3 O 4 had a lower band gap and, therefore, a better photocatalytic performance whereby 90–95% of the degradation was reached in 70 min, which is better than undoped Fe 3 O 4 . Besides removing dyes, the nanoparticles were also powerful antibacterials against gram-positive Staphylococcus aureus and gram-negative Proteus vulgaris , which also indicates their versatile nature. The originality of the given work is in the green synthesis of Alstonia scholaris extract, Zn-doping approach of maximum photocatalytic activity, and dual functionality of the research in both wastewater degradation and microbial suppression, which could be taken as the sustainable route of wastewater treatment and anti-microbial control.