Fast deposition of porous iron oxide on activated carbon by microwave heating and arsenic (V) removal from water

• Porous iron oxide nanoparticles were deposited on AC by microwave radiation.
• Uniform deposition with high loadings was obtained within very short time.
• 20.27% of iron loading was obtained in 9 min. of microwave hydrothermal synthesis.
• High As(V) uptakes were obtained in the range of pH 6.0–8.0.

Iron oxide nanoparticles were deposited on activated carbon (AC) with the microwave hydrothermal (MH) treatment technique. The effect of heating duration and AC’s oxidation on structural properties were studied. X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), focused ion beam (FIB) microscopy, Brunauer, Emmett and Teller (BET), and porous texture analyses were utilized to characterize iron oxide/AC system. XRD characterization revealed dependence of crystal structure to heating duration. BET and porous texture analyses showed some pore filling in AC, but pore volume increase in iron oxide particles. With the MH technique, porous iron oxide was obtained with a high loading value of 20.27% in just 9 min. Additionally, As(V) adsorption capacity of synthesized materials was studied. As(V) adsorption onto iron oxide deposited supports obeyed Langmuir and pseudo-second order models. Batch adsorption experiments revealed a high efficiency of As(V) removal with the MH synthesized materials. Maximum adsorption capacity was 27.78 mg/g, and for a loading of 0.75 g/L, 99.90% uptake was reached within just 5 min due to the porous nature of iron oxide. Moreover, more than 99.00% of uptake was obtained within the pH range of 6–8. The results suggest that MH synthesized iron oxide particles are promising materials for water treatment.

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