Steady-state redox sorption of oxygen dissolved in water on granular layers of copper-ion-exchange nanocomposites

The process of redox sorption of oxygen dissolved in water on cathodically polarized granular layers of copper-ion-exchange nanocomposites depending on the water flow rate and the value of polarizing current is studied. It is observed that initially the amount of absorbed oxygen exceeds the amount of leaked electricity. With time, the chemical activity of the nanocomposite decreases, and oxygen continues to be sorbed and further recovered mainly due to the current component of the process. Simultaneous increase in the water flow rate and the strength of the limiting current is concluded to have a favorable effect on the rate of oxygen uptake. Maintaining the constancy of the water supply mode and the respective current strength ensures a stationary course of diffusion, chemical, and electrochemical stages. Successive stages of external diffusive oxygen transfer to the surface of nanocomposite grains, intra-diffusive oxygen transfer along the grain pores and chemical oxidation of copper nanoparticles to oxides characteristic of the final sources are found to be compensated by the stages of electroreduction of oxygen from surface adsorbed complexes and regeneration of oxidation products into metallic copper nanoparticles. The nanocomposite is a continuous source of newly reduced metal particles and contributes to the oxygen redox sorption process reaching the stationary mode. Unlike the nonpolarizable granular layer, the oxygen concentration remains at a low constant level under the conditions of the maximum admissible electric current applied.