Optimization of ultrasound-assisted removal of crystal violet dye, Cu(II), and Cd(II) ions by magnetic CoFe₂O₄ nanoparticles using central composite design

In this study, magnetic CoFe₂O₄ nanoparticles (CFO NPs) were fabricated by coprecipitation method for the removal of crystal violet (CV), Cu(II) and Cd(II) from environmental water samples in batch mode. This study investigated the effect of CFO NPs on the removal of CV, Cu(II), and Cd(II) using the response surface methodology (RSM) based on central composite design (CCD). For this purpose, batch experiments were designed and performed to evaluate the effect of variables such as pH, adsorbent amount, sonication time, and concentration of pollutants using RSM. Under optimal conditions (ultrasound time of 17 min, pollutant concentration of 15 mg L⁻¹, CFO NPs amount of 0.24 g, and pH = 6), the removal efficiency was achieved in the range of 95.86–99.82%. Evaluating the reusability of the CFO NPs showed that the CFO NPs adsorbent can be reused for up to 5 cycles while maintaining its high efficiency in removing CV, Cu(II) and Cd(II). The removal efficiency of CV, Cu(II) and Cd(II) was obtained in the range of 91.68–97.59% for real samples. Overall, the results revealed that CFO NPs adsorbent has a high ability to remove CV, Cu(II) and Cd(II) from different water samples.