Photocatalytic removal of Cr(VI) using cobalt ferrite-coated recycled cigarette butts under visible light: optimization via response surface methodology

mg/J. The operational cost of this system was calculated at US$33.50 per kilogram, indicating its practical and economic viability compared to other visible-light systems. Furthermore, toxicity analysis using Daphnia magna confirmed a significant reduction in toxicity after treatment. Overall, the findings of this research indicate that the CoFe₂O₄-RCBs nanocomposite can serve as an effective, environmentally friendly, and promising catalyst for the removal of hexavalent chromium from contaminated water.