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Metals 2015, 5(4), 1770-1787;

Preparation of Potassium Ferrate from Spent Steel Pickling Liquid

Department of Environmental Science and Engineering, Tunghai University, Taichung 40704, Taiwan
Author to whom correspondence should be addressed.
Academic Editors: Suresh Bhargava and Rahul Ram
Received: 31 July 2015 / Revised: 7 September 2015 / Accepted: 18 September 2015 / Published: 24 September 2015
(This article belongs to the Special Issue Hydrometallurgy)
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Potassium ferrate (K2FeO4) is a multi-functional green reagent for water treatment with considerable combined effectiveness in oxidization, disinfection, coagulation, sterilization, adsorption, and deodorization, producing environment friendly Fe(III) end-products during the reactions. This study uses a simple method to lower Fe(VI) preparation cost by recycling iron from a spent steel pickling liquid as an iron source for preparing potassium ferrate with a wet oxidation method. The recycled iron is in powder form of ferrous (93%) and ferric chlorides (7%), as determined by X-ray Absorption Near Edge Spectrum (XANES) simulation. The synthesis method involves three steps, namely, oxidation of ferrous/ferric ions to form ferrate with NaOCl under alkaline conditions, substitution of sodium with potassium to form potassium ferrate, and continuously washing impurities with various organic solvents off the in-house ferrate. Characterization of the in-house product with various instruments, such as scanning electron microscopy (SEM), ultraviolet-visible (UV-Vis), X-ray diffraction (XRD), and X-ray absorption spectroscopy (XAS), proves that product quality and purity are comparative to a commercialized one. Methylene blue (MB) de-colorization tests with in-house potassium ferrate shows that, within 30 min, almost all MB molecules are de-colorized at a Fe/carbon mole ratio of 2/1. View Full-Text
Keywords: potassium ferrate; wet oxidation method; steel pickling liquid; ferrous chloride; ferric chloride; Fe k-edge XAS potassium ferrate; wet oxidation method; steel pickling liquid; ferrous chloride; ferric chloride; Fe k-edge XAS

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Wei, Y.-L.; Wang, Y.-S.; Liu, C.-H. Preparation of Potassium Ferrate from Spent Steel Pickling Liquid. Metals 2015, 5, 1770-1787.

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