Sustainable generation of homogeneous Fe(VI) oxidant for the room temperature removal of gaseous N2O by electro-scrubbing process

Abstract

A high valent Fe(VI) homogenous catalyst was synthesized following electrochemical route for the efficient removal of a greenhouse gas (N2O) by mediated electro catalytic oxidation (MEO) in an electro-scrubbing process. This paper describes the room temperature degradation of N2O using a consistently generable hexavalent Fe(VI) homogenous catalyst. The ferrate (VI) was electrochemically generated by employing a membrane divided cell, and quantified by monitoring the changes in the ORP (oxidation/reduction potential) along with a potentiometric titration by the chromite method using chromium Cr(III) as a titrant. In addition, the formation of ferrate (VI) was confirmed through UV–visible spectroscopy study results. The change in the ORP values from 360 mV to 253 mV and the change in concentration of electrogenerated Fe(VI) from (4 mM) to (2.9 mM) during N2O removal confirmed that N2O removal followed a mediated electrocatalytic oxidation (MEO) process. An online FTIR gas analyzer study results revealed approximately 90% degradation efficiency of N2O during the MEO process in a gas mixture containing 5 ppm N2O at a 0.2 L min−1 gas flow rate at ambient temperature. The energy efficiency for N2O removal using the Fe(VI) mediator resulted in ten times higher (0.0021 g kWh−1) than the existing MER (0.00063 g kWh−1) process. The possible consistent generation of a homogenous electrocatalyst and its degradation of greenhouse gases at ambient temperature process can be explored to a more practical level.