Removal of aqueous As(III) Sb(III) by potassium ferrate (K2FeO4): The function of oxidation and flocculation

Abstract

This study investigated the effects of potassium ferrate (K2FeO4) dosage, pH, and reaction time on the removal of aqueous As(III) and Sb(III), and revealed the oxidation and flocculation mechanism of K2FeO4. The results show that the removal efficiencies of As(III) and Sb(III) were highly related to the hydrolysate of K2FeO4 under acidic conditions, while the efficiencies were low under alkaline condition, owning to the electrostatic repulsion between iron nanoparticles and charged As/Sb species. The increased dosage and reaction time improved the adsorption performance. Based on the comparative experiments with FeCl3, the simultaneous removal of As(III) and Sb(III) by K2FeO4 suggested that As(III) was eliminated due to the processes of oxidation, flocculation, and chemical precipitation, while Sb(III) was removed mostly by oxidation and flocculation. The generated precipitates were characterized with surface analysis and the results support that the oxidization property of K2FeO4 was essential during the removal of As(III) and Sb(III), and removal mechanisms between both elements were different.