Development and reaction mechanism of efficient nano titanium electrode: Reconstructed nanostructure and enhanced nitrate removal efficiency

In this study, an efficient nano titanium electrode (ENTE, treated electrode) was fabricated for electroreduction of nitrate in groundwater. The nano titanium electrode showed a regular reticulate nanostructure by scanning electron microscopy. An acid environment and electrochemical treatment of the nano titanium electrode (NTE, untreated electrode) induced ruptures into its regular nanostructure, which led to improved nitrate electroreduction efficiency. X-ray photoelectron spectra revealed titanium dioxide in the anatase phase at the electrode surface and the treatment did not affect the composition or crystal form. The electroreduction activity of the treated electrode (94.6%) was almost twice as high as that of the untreated electrode (65.8%). In the presence of NaCl, by-products that formed during electroreduction, particularly ammonia, were removed by hypochlorite ions. The optimum NaCl concentration in the electrochemical system was determined as 1.5 g/L, which led to a low level of ammonia formation (< 1.0%) and an overall efficiency total nitrogen removal of 92.6%.