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Novel KMnO₄-modified iron oxide for effective arsenite removal

Huang, Yao-Hui, Shih, Yu-Jen, Cheng, Fu-Ji
Journal of hazardous materials 2011 v.198 pp. 1-6
X-ray diffraction, adsorbents, adsorption, arsenic, arsenites, fluidized beds, goethite, iron, iron oxides, manganese, oxidation, potassium permanganate, scanning electron microscopy, sorption isotherms, surface area
This work demonstrates the synthesis of a novel KMnO₄-modified form of iron oxide, MnBT-4, using a fluidized bed reactor (FBR) for the adsorptive removal of arsenic (III)/(V). Characterization by XRD, BET, and SEM indicated that the BT-4 support was poorly crystallized goethite (α-FeOOH) with a specific surface area of 229m²g⁻¹. In FBR experiments of synthesizing MnBT-4, the Fe and Mn salts were found to have an optimal dosage ratio of less than 4, which maximized the KMnO₄ immobilization efficiency. The immobilized Mn compounds on MnBT-4 underwent an additional oxidation step of As (III), promoting arsenic adsorption. When applied MnBT-4 for As (III) removal from solution, the sorption isotherm was accurately fitted with Langmuir and Freundlich models, while the maximum adsorption capacity of 27.4mgg⁻¹ exceeded those of other adsorbents in the literature. Batch experimental results revealed that both raw BT-4 and MnBT-4 could take up a large amount of As (V). However, the MnBT-4 provided a substantially higher As (III) removal efficiency than BT-4.