Preparation of magnetite nanoparticles by high-energy planetary ball mill and its application for ciprofloxacin degradation through heterogeneous Fenton process

In this study, the heterogeneous Fenton oxidation of ciprofloxacin (CIP) in an aqueous solution was examined over the nano-sized magnetite (Fe₃O₄) as a catalyst supplied through high-energy planetary ball milling process. To characterize the magnetite samples after and before ball milling operation, the X-ray diffraction (XRD), High-resolution scanning electron microscopy (HR-SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FTIR) analysis were applied. The catalytic properties of the magnetite were considerably improved because of the enhancement in its physical properties, resulted from milling process. The findings also indicated that 6 h ball-milled magnetite demonstrated better properties for elimination of CIP of about 89% following 120 min reaction at optimal conditions of H₂O₂ 12 mM, Fe₃O₄ 1.75 g L^-1, CIP 10 mg L^-1 and pH 3.0. The effects of various operational parameters, including the initial pH of the solution, H₂O₂ initial concentration, catalyst dosage, milling time and CIP initial concentration was investigated. Application of organic and inorganic scavengers considerably decreased the CIP removal efficiency. Correspondingly, with respect to the leached iron values at pH 3, it was concluded that CIP elimination was mainly occurred through heterogeneous Fenton procedure. This process included the adsorption and oxidation phases in which the hydroxyl radicals (OH) played a significant role. GC-MS analysis was used for recording of the generated intermediates of the CIP removal in the course of heterogeneous Fenton process.

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.

Combination of ultrasonic and Fenton processes in the presence of magnetite nanostructures prepared by high energy planetary ball mill

High energy planetary ball milling process was used to prepare magnetite nanostructures from natural magnetite. The natural and ball-milled magnetite samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (HR-TEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FT-IR). The results of EDX indicated the presence of main elements including Fe and O in the structure of both unmodified and milled magnetite samples. The specific surface area of catalyst increased from 0.9116m²/g to 28.692m²/g after ball-milling process. The catalytic activity of prepared magnetite nanostructures was evaluated towards degradation of Acid Blue 185 (AB185) in ultrasonic assisted heterogeneous Fenton reaction. 6h ball-milled catalyst exhibited the higher catalytic activity in degradation of AB185. The high degradation efficiency was obtained at initial pH of 3. Increasing the concentration of H₂O₂ from an optimum value of 15mM led to decrease in degradation efficiency because of scavenging effect of H₂O₂ on hydroxyl radicals. The optimized catalyst concentration was obtained 1.5g/L. Increasing initial dye concentration from 20 to 120mg/L led to decrease in degradation efficiency from 99 to 88%. The prepared magnetite nanostructures exhibited good stability in repeated cycles. The produced intermediates of the degradation of AB185 in ultrasonic assisted heterogeneous Fenton process were monitored by GC-MS analysis.