在不同pH值的溶液中，催化剂表面吸附的物质种类不同。在酸性条件下，催化

In solutions with different pH values, the types of substances adsorbed on the catalyst surface are different. Under acidic conditions, the surface of the catalyst mainly adsorbs hydrogen, and the surface of the catalyst is in a reduced state. The adsorbed H + can promote the further generation of NHQ +; it is not conducive to the formation of NHQ + under neutral and alkaline conditions, which may be due to the increase in pH with the solution NHQ + decomposes on its own, and ammonia is more easily oxidized in the form of nonionic NH :. Under alkaline conditions, the surface of the catalyst mainly adsorbs oxides (such as OH, OH, and Ox-), and the surface is in an oxidized state. These oxides occupy the active center of the catalyst, which competes with nitrate for adsorption, and the higher the pH , The higher the coverage, the nitrate reduction activity decreased significantly. Abdallah R et al. [Oat used a porous copper electrode as the cathode to electrolyze nitrate. The experiment found that most of the reduction products of nitrate in neutral solution were ammonia nitrogen, the selectivity of ammonia nitrogen was up to 96%, and the concentration of ammonia nitrogen in acid solution was significantly reduced, and The current efficiency in neutral solutions is significantly higher than in acidic solutions. Maria Dort-siou et al. [35] studied the reaction rate and product composition of the electrochemical reduction of NO3 by 6 kinds of metal electrodes (Sn, Bi, Ph, Al, Zn, Ir>). Foreground metal electrode. When pH> 4, the main products are Nz, NZO, ammonia and nitrite; when the pH is 0-4, the main products are ammonia and light amine.

In different pH-value solutions, the type of material adsorptioned on the surface of the catalyst was different. Under acidic conditions, the catalyst surface mainly absorbs hydrogen, the catalyst surface is reduced state, the adsorption of H-plus can promote the further generation of NHQ plus, in neutral and alkaline conditions is not conducive to the generation of NHQ, may be due to the increase of the solution pH NHQ plus self-decomposition, ammonia in the form of non-ion NH: the presence of more easily oxidized. Under alkaline conditions, the main adsorption oxides (e.g. OH, OH1 and Ox-) on the surface of the catalyst surface are oxidized, which occupy the active center of the catalyst, compete with nitrates for adsorption, and the higher the pH, the higher the coverage, the decrease in nitrate reduction activity. Abdallah R and other .oat using porous copper electrodeas as cathode electrolytic nitrates, the experiment found that most of the reductive products of nitrate in the neutral solution were ammonia nitrogen, ammonia nitrogen selectivity of up to 96 percent, the concentration of ammonia nitrogen in the acidic solution was significantly reduced, and the current efficiency in the neutral solution was significantly higher than in the acidic solution. Maria Dort-siou and others have studied the reaction rate and product composition of six metal electrodes (Sn, Bi, Ph, Al, Zn, Ir) electrochemical lyse N03, and considerbi to be the most promising metal electrode in water treatment. At pH 4, the main products are Nz, NZO, ammonia and nitrite, and at pH 0-4, the main products are ammonia and light amine.

In the solution with different pH value, the adsorbed substances on the catalyst surface are different. Under acidic condition, hydrogen is mainly adsorbed on the surface of catalyst, and the surface of catalyst is reduced state. The adsorbed H + can promote the further formation of nhq +; under neutral and alkaline conditions, it is not conducive to the formation of nhq +. It is possible that ammonia is more easily oxidized in the form of non-ionic NH: due to the self decomposition of nhq + with the increase of solution pH. In the alkaline condition, the surface of catalyst mainly adsorbs oxides (such as Oh, oh - and ox -), which occupy the active center of catalyst and compete with nitrate. The higher the pH is, the higher the coverage is, the lower the reduction activity of nitrate is. Abdallah R et al. [oat used porous copper electrode as cathode to electrolyze nitrate. It was found that most of the reduction products of nitrate in neutral solution were ammonia nitrogen, and the selectivity of ammonia nitrogen was as high as 96%. The concentration of ammonia nitrogen in acid solution was significantly reduced, and the current efficiency in neutral solution was significantly higher than that in acid solution. Maria DORT Siou et al. [35] studied the reaction rate and product composition of electrochemical reduction of n03-1 by six kinds of metal electrodes (SN, Bi, pH, Al, Zn, IR >), and considered that BI was the most promising metal electrode in water treatment. When pH > 4, the main products are NZ, NZO, ammonia and nitrite; when pH is 0-4, the main products are ammonia and light amine.<br>