High levels of nitrate in drinking water are considered dangerous as they cause cancer and thyroid problems. The electrocatalytical reduction (ER) of this species is emerging as a prominent solution since it reduces NO3- to the innocuous nitrogen gas. Recently, abundant low-cost earth abundant materials, as carbon-based, were pinpointed as promising electrodes for ER, since they are innovative, low-cost, and sustainable for the water treatment marketplace. Carbon felt (CF) is a satisfactory example, with good electronic conduction, high surface area and porosity able to provide abundant redox reaction sites, and excellent electrolytic efficiency. In order to create active sites on its surface, this material normally undergoes an activation process. In this work, CF was activated using thermal, chemical, electrochemical and plasma techniques with the objective to understand the electrocatalytic behavior of this procedure on the ER of nitrate. Discussion was sustained in terms of the mterial characterization (FTIR, XPS, and SEM), relating O/C, sp2/sp3 and C=O/C-O ratio parameters, performed balance considering electroreduction kinetics, selectivity towards nitrogen evolution, electrical energy per order and current efficient. The results clearly evidenced that depending on the type of activation, different functional groups (and amounts) may be formed, affecting the process performance, current efficiency, and even operating costs. Plasma activation provided the most competitive results when compared to the other activation techniques tested in terms of nitrate reduction kinetics thus opening a possibility of its simple and quick use in this environmental context.

Effect of carbon felt activation on the electrocatalytic reduction of nitrate: material characterization and electrochemical performance

ACS Spring Meeting 2021

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