Biogenic fabrication of spinel nickel ferrite imprinted on Bifurcaria bifurcata Macro-Alga activated carbon for the adsorption of ciprofloxacin and metronidazole

• NiFe@BBAL was successfully synthesized through the coprecipitation method. • Nife@BBAL proved to be efficient for the removal of CIP and MET with over 96% removal. • NiFe@BBAL successfully performed well over five cycles. • The toxicity test of the pristine NiFe@BBAL proved to be not toxic on E.coli and S. aureus species. • NiFe@BBAL was efficient in the removal of CIP and MET in environmental samples such as groundwater, wastewater and tap water. The rise in globalization and industrialization has led to an increase in population, increasing improperly treated discharge containing dyes, pharmaceuticals, pesticides etc in the water bodies. This has led to the need to remove these contaminants from water sources. The NiFe@BBAL adsorbent was developed and analyzed using various techniques such as FTIR, XRD, SEM, and XPS. The effectiveness of the NiFe@BBAL in adsorbing Ciprofloxacin (CIP) and metronidazole (MET) in water was tested. The adsorption of CIP and MET, both individually and in mixtures, was studied. The kinetic sorption experiments showed that the adsorption followed a pseudo-second-order model, with a higher R 2 of 0.9934 for MET compared to 0.9916 for CIP. This suggests that the rate-limiting step is chemisorption. The primary adsorption mechanisms for both CIP and MET were hydrogen bonding, hydrophobic interactions, and electrostatic interactions, while CIP also involved electrostatic and metal complexation interactions. The NiFe@BBAL effluent showed no toxic effects on bacteria, indicating that no harmful material was leached in the effluent. The NiFe@BBAL demonstrated excellent performance and stability in removing 97.64% CIP and 97.62% MET in single contaminant experiments, and 57.33% CIP and 70.69% MET in cocktail mixture experiments. This can be attributed to the smaller structure of MET compared to CIP, allowing it better access to the active site, leading to higher adsorption. Furthermore, the repeated use of the adsorbent proved to be stable in the removal of CIP and MET over five cycles, demonstrating that the material is sustainable and suitable for large-scale experiments.