Fang Liu

This study investigated the electrochemical degradation of N-nitrosodimethylamine (NDMA) using a Ti-based nano-electrode as the cathode and Ti/Pt, Ti/IrO₂, and Ti/RuO₂ electrodes as the anode, respectively. Efficient electrochemical removal of NDMA was achieved. By studying the effect of Cl⁻ concentration, the reaction was found to follow a pseudo-first-order kinetic model. In addition, the factors influencing the removal of NDMA were optimized by response surface methodology. The Box–Behnken design was employed to develop mathematical models for removal of NDMA, which was considered to indicate a relatively high correlation between observed and predicted values. Furthermore, the cyclic voltammetric waves suggested that NDMA was removed via both oxidation and reduction. Chronoamperometry results showed that the Ti-based nano-electrode had a larger specific surface area and stronger electrochemical activity than pure Ti. Thus, the present electrochemical treatment is an effective method for the removal of NDMA from aqueous solutions.

A novel Pd-TNPs (Palladium-TiO₂ Nanopores) bimetallic nanoelectrode was developed to improve the removal rate of nitrate by electrochemical method. The Pd-TNPs bimetallic nanoelectrode was fabricated by plating Pd on TiO₂ nanopores. In the Pd-TNPs bimetallic nanoelectrode, Ti nanostructure can increase the specific surface area, meanwhile Pd nanoparticles can raise ratio of nitrogen to hydrogen and present high activity for nitrate reduction. According to scanning electron microscope(SEM), the Pd-TNPs bimetallic nanoelectrode is a porous morphology with lamellar deposit on it. Elements on the surface of Pd-TNPS bimetallic electrode were observed by energy-dispersive X-ray spectroscopy(EDS), Ti, Pd and O respectively. Using the Pd-TNPs bimetallic nanoelectrode, nitrate removal efficiency achieved 91.7% in the presence of 0.50 g/L Na₂SO₄ after 90 min electrolysis. The Pd-TNPs nanoelectrode exhibited higher nitrate reduction rate, under the same current conditions, the removal rate of the Pd-TNPs bimetallic nanoelectrode was 224.6% compared with that of the Ti nanoelectrode. Nitrate could be completely removed using the Pt anode in the presence of 0.5 g/L NaCl, and with little amount of ammonia and almost no nitrite detected in the treated solution. For the same initial nitrate concentration, the nitrate removal rate increased sharply with increasing current density.