Enhanced removal of basic violet 10 by heterogeneous sono-Fenton process using magnetite nanoparticles

The removal of basic violet 10 (BV10), which is known as a cationic dye, from aqueous solution was studied by employing a heterogeneous sono-Fenton process over the nano-sized magnetite (Fe₃O₄) which had been prepared by the milling of magnetite mineral using a high-energy planetary ball milling process. The magnetite samples were characterized using the X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), Fourier transform infrared spectroscopy (FTIR), and inductively couple plasma mass spectrometer (ICP-MS). It was found that the catalytic activity of the ball-milled magnetite sample was enhanced along with the improvement in its physicochemical properties; also, the ball-milled magnetite of 6 h displayed the highest catalytic activity in BV10 removal by the heterogeneous sono-Fenton process as compared with that for 4 h (66.12% after 120 min) and 2 h (48% after 120 min).The effect of operational parameters, namely, pH solution, catalyst dosage, the initial H₂O₂ concentration, ultrasonic power and the initial BV10 concentration, on the removal efficiency (RE%) of BV10 was investigated. The optimum conditions for the BV10 RE% were: the pH value of 3, the catalyst dosage of 1.5 g L^-1, the initial H₂O₂ concentration of 36 mM, the ultrasonic power of 450 W L^-1, and the initial BV10 concentration of 30 mg L^-1. The RE% of BV10 was 75.94% at these conditions after the reaction time of 120 min. The trapping experiments revealed that OH radicals were the dominant oxidative species, but O₂^-/HO₂ radicals also had a partial role in the removal of BV10.The reusability of the magnetite nanoparticles revealed about 28% decrease in the removal efficiency within five consecutive runs. The results obtained through GC-MS analysis also confirmed the efficient removal of BV10 molecules in the aqueous solution during the process.