New Processes for Alkali Ferrate Synthesis

A new process for the synthesis of the potassium ferrate(VI) salt was developed at the University of Nancy, France under an EEC program; started in 2001. This program had an objective of synthesizing a large quantity of ferrate in order to feed large scale applications in the field of water treatment such as drinking water, municipal waste water, and industrial waste water treatment. The raw materials used were ferrous sulphate, potassium hydroxide, and calcium hypochlorite (or chlorine). In this process, mixing of three solids took place in a mixer in which the potassium ferrate(VI) salt was stabilized. Another objective of the program was to develop synthesis of solid sodium ferrate(VI), which is cheaper to produce because its preparation requires less expensive materials: caustic soda instead of potassium hydroxide and sodium hypochlorite (or chlorine gas) instead of calcium hypochlorite. The final objective was to develop a better technology, which could be cheaper and easier to scale-up. This chapter also describes successful results of lab and small pilot tests.