A new electrochemical process for making K2FeO4

A new process for producing the oxidizing agent potassium ferrate (VI) (K2FeO4) can routinely generate multi-kilogram quantities per day, say scientists. Ferratec (St. Louis, Mo.; www.theincubationfactory.com) and partner Electrosynthesis (Lancaster, N.Y.; www.electrosynthesis.com) have licensed the process technology from Battelle (Columbus, Ohio; www.battelle.org) and are looking toward commercial-scale ferrate production.

The common laboratory method for making the compound involves chlorination of ferric salts, a process that makes only gram quantities and has not been found to be scalable. The new process is based on an electrochemical cell with an iron anode in a strong caustic medium. As low voltage is applied, the cell produces K2FeO4 as a slurry, and hydrogen gas. The ferrate is removed continuously from the circulating electrolyte and isolated by solid/liquid separation. Recovered electrolyte is recycled back to the cell.

Relying on electrochemistry rather than chlorination synthesis methods was a key technology development in assembling a viable process and enabling high yields, explain Bruce Monzyk and Mike von Fahnestock, process chemists and engineers at Battelle. The other key innovation, they say, was varying the power across the anode, which eliminates the accumulation of unstable or solid intermediates and keeps the anode from passivating” — a problem that has plagued past efforts to produce ferrate electrochemically.

Advantages of the new process include a high-purity (>95%), highly stable (tolerates 70°C) product and a small and relatively clean waste stream. The kilogram yields were achieved on a single, commercial-scale cell, but the cells are modular, and can be replicated to scale-up, notes Andy Wolter, chief operating officer of Ferratec and parent company, The Incubation Factory.

Initially, Ferratec is targeting a handful of the many applications for the powerful oxidizer, including use as a broad-spectrum disinfectant, a water quality tool and for selective oxidations in fine chemical syntheses.