This paper explores the feasibility of using potassium manganate (K2MnO4) in water treatment. Manganate (Mn(VI)), like ferrate (Fe(VI)), can act as both an oxidant and a coagulant/adsorbent arising from the formation of insoluble manganese dioxide (Mn(IV)) from the chemical reduction of MnO42−. In this paper the basic properties of K2MnO4 are described, including the standard electrode potential which exceeds several oxidizing agents commonly used as water treatment chemicals. The methods of preparing K2MnO4 are outlined, and the main reaction products, which are potassium permanganate (KMnO4) and manganese dioxide (MnO2), and their use in water treatment are summarized. Some preliminary results of water treatment tests in China and at Imperial College London are presented, and alternative ways of applying K2MnO4 in water treatment are proposed. Finally, the paper provides a preliminary evaluation of the economic feasibility of using K2MnO4 in comparison with alternative chemicals, such as KMnO4. Overall, it is believed that K2MnO4 may be a useful water treatment chemical in the future.
Keywords: coagulation, potassium manganate, pre-oxidation, water treatment