Thermal oxidation of iron oxide nanosheets in the presence of potassium iodide for chromium removal

Tan, Zhen Sheng (2022) Thermal oxidation of iron oxide nanosheets in the presence of potassium iodide for chromium removal. Final Year Project, UTAR.

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Abstract

Over the years, environmental pollution due to improper handling of Cr (VI) contaminant wastewater leads to high concerns from various researchers around the world. Up to date, Cr (VI) removal technique using nanomaterials is highly adopted due to the advantages of greater removal efficiency and cost-effectiveness. It is discovered that iron oxide nanostructures are favourable in removing Cr (VI) ions due to its strong magnetic properties. In this work, iron oxide nanosheets were produced by thermal oxidation with potassium iodide (KI). Sample characterisation tests of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Cr (VI) removal analysis were conducted on the oxidised samples to determine the optimum oxidation temperature and duration to grow iron oxide nanosheets. SEM analysis showed that oxidation temperatures lower than the optimum temperature of 500 °C were insufficient to grow uniform and densely packed iron oxide nanosheets with high areal density. Besides, more obvious nanosheets with high areal density nanosheets were produced on the iron foil oxidised at the optimum duration of 2.5 h, which possessed the greatest average width and height with rather fine thickness. In XRD analysis, various oxides including hematite, magnetite, and potassium iron oxide (K2FeO4) as the dominant peak were identified on the samples oxidised with KI powder. Iron foil oxidised for optimum duration shows the highest intensities in overall, indicating that the sample was highly crystallised. Moreover, the Cr (VI) removal test conducted proved that the sample oxidised under optimum parameters achieved the best Cr (VI) removal efficiency of 83.22 % in 30 min as compared to those samples oxidised for other oxidation durations. This could be attributed to better morphological and structural properties possessed by the best sample which provided larger surface area for more sites to undergo electrostatic reaction with Cr (VI) ions. It was also justified that the presence of KI powder in the oxidation of iron foil enhanced the Cr (VI) removal efficiency.

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