Sulfentrazone dechlorination by iron-nickel bimetallic nanoparticles

The sulfentrazone dechlorination using bimetallic nanoparticles of Fe/Ni was studied. Different variables that could influence the sulfentrazone conversion were investigated, such as nitrogen atmosphere, pH and dosage of the nanoparticles and initial concentration of sulfentrazone. The best results were obtained using controlled pH (pH 4.0) and 1.0 g L⁻¹ of nanomaterials, resulting in 100 % conversion in only 30 min. Kinetic studies were also conducted, evaluating the influence of different nanoparticle dosages (1.0 to 4.0 g L⁻¹), system temperatures (20 to 35 °C) and nickel levels in the composition of the nanomaterials (0.025 to 0.10 gNi/gFe). The mechanism of sulfentrazone conversion has changed due a direct reduction on the catalytic activity sites and indirect reduction by atomic hydrogen. Both mechanisms have followed pseudo-first order models. The conversion rate improved when the dosage of the nanomaterials, system temperature and nickel content in the composition of the nanocomposites were increased. Finally, the conversion products were elucidated by mass spectrometry and toxicity assays were performed using Daphnia Similis. The results showed that the dechlorination product is less toxic than sulfentrazone. - Highlights: • The complete dechlorination of sulfentrazone was obtained by Fe–Ni nanoparticles. • The maximum dechlorination was observed at pH 4.0 under aerobic conditions. • A mechanism change was observed in the dechlorination process. • The nickel present in the composition of the nanoparticles acted as a catalyst. • The reused nanoparticles showed excellent degradation results. - The dechlorination of sulfentrazone was obtained by Fe-Ni nanoparticles through direct and indirect reduction, i.e., electron donation by Fe and atomic hydrogen, respectively.