Preparation of Potassium Ferrate and Its Effectiveness on the Removal of As(III) and Pb(II)

Potassium ferrate (K2FeO4) was synthesized by hypochlorite oxidation. Orthogonal method was applied to optimize the synthesis process. The obtained K2FeO4 had a purity of 95% or higher. The synthesized K2FeO4 was used as a coagulant to remove As(III) and Pb(II) in single and bi-solute systems. Effects of K2FeO4 dosage and operating pH on the removal of As(III) and Pb(II) were studied. In the single system, results shows that at pH 65, Fe/As=16 (wt/wt) and Fe/Pb=4 (wt/wt), the residual As and Pb were less than 10 g/L. In the bi-solute system, ferrate could remove As and Pb simultaneously. When ferrate dose was 24 mg/L, the removal rates of As and Pb were 99.30% and 100%, respectively. At low ferrate dose, the competitive adsorption behavior of As(III) and Pb(II) in the bi-solute system was observed. Visual MINTEQ software was used to calculate and simulate metal speciation in solution at equilibrium aiming at elucidate the removal mechanism of As and Pb by potassium ferrate.