Facile synthesis of CaMn1-xFexO3 to incorporate Fe(IV) at high ratio in perovskite structure for efficient in situ adsorption-oxidation of As(III)

Soluble Fe(IV) has been proposed as primary reactive species in advanced oxidation technology, however, Fe(IV) in solid-state oxidant is rarely reported. This study reports a facile synthesis of CaMn1-xFexO3 (0.1 ≤ x ≤ 0.7) containing high ratio of Fe(IV) by low-temperature calcination of the ball milling precursor and evaluates its adsorption-oxidation performances of As(III). Although Fe(IV) and Mn(IV) inside CaMn1-xFexO3 both act as electron acceptor species, with × for Fe ratio increased, charge transport capability and oxidation performance of As(III) to As(V) of the CaMn1-xFexO3 materials can be raised dramatically with more iron incorporated. With sample CaMn0.3Fe0.7O3, the maximal adsorption capacity for As(III) reaches 120.78 mg/g with the ratio of oxidized As(V) as high as 86.4% in a wide pH range of 2 ∼ 10. More importantly, excellent cyclability and stability are observed and 83% of the initial adsorption-oxidation capacity still retains even after 5 cycles, and leaching concentrations of the metal ions (Fe/Mn) are far below the emission standard (0.5 mg/L). With an aid of environment-friendly ball milling process, the idea to obtain high valent Fe by a simple incorporation into a specific crystalline structure of perovskite offers a new approach for synthesizing active oxidizing species of Fe(IV). Further, the synthesis of solid oxidants would transform the redox reactions from a liquid phase reaction process to a solid–liquid reaction process, which could be conducive to the occurrence of in-situ oxidation and fixation of pollutants to reduce their mobility, and much contribution is expected to the development of advanced oxidization process in wastewater treatment using the easy handling solid-state oxidants.