Electrocatalytic Denitrification On Removal Of Nitrate Nitrogen In Water By Paired Electrolysis

The pollution of nitrate in groundwater and its effects have gradually aroused people's general concern.The world health organization?WHO?stipulates that the concentration of NO₃^--N in drinking water should not exceed l0mg/L in the drinking water quality standard.This study carried out an experimental study on the removal of nitrate and by product ammonia nitrogen from groundwater by electrocatalytic reduction.The removal of nitrate and by-product ammonia nitrogen from groundwater by electrocatalytic reduction is closely related to the synergistic action of paired electrodes.This topic through test electrode potential window,select a different range of electrode potential window combination.By comparing their removal effects in the electrocatalytic reduction of nitrate nitrogen,the optimal electrode combination for electrocatalytic reduction of nitrate nitrogen was determined.The effect of electrocatalytic denitrification on nitrate wastewater treatment with the optimal paired electrodes was studied in the following experiments,and the effects of different reaction parameters on nitrate removal efficiency and product composition were investigated.In this paper,through the analysis of different experimental results,constant potential electrolysis and product distribution,preliminary exploration of the reduction path of electrocatalytic reduction of nitrate nitrogen through experimental research and analysis,the following conclusions are drawn:The larger the potential window of the electrode,especially the lower the cathode hydrogen evolution overpotential,the more favorable it is for the reduction reaction and the synthesis of the intermediates with reductibility.By testing the potential of the electrode potential,the electrode combinations with different potential window range were selected.By comparing the removal effect of nitrate nitrogen with four different electrode combinations,it was found that under the same reaction conditions,Cu-Sn cathode and Ti/SnO₂-Sb anode combination had the best removal rate of nitrate nitrogen in nitrate wastewater,and the by-product NH₄⁺-N generated less.By comparing the cyclic voltammetry curves,it can be seen that the good effect of Ti/SnO₂-Sb anode combined with Cu-Sn cathode is realized by the synergistic action of anode and cathodeThe Cu-Sn cathode combination Ti/SnO₂-Sb anode was used for electrocatalytic denitrification with constant current to remove nitrate.Under the conditions that the area ratio of cathode to anode was 6.25:1,the current density was 16 mA/cm²,the initial concentration of nitrate nitrogen was 80.0 mg/L,the concentration of Na₂SO₄ was 0.015 mol/L,the initial pH value was 7,and the concentration of Cl^-was 1g/L,the removal rate of nitrate nitrogen after 5 h of electrocatalytic reduction was 92.7%,the generated by-product nitrite nitrogen and ammonia nitrogen concentration were both 0.0mg/L,the nitrogen selectivity was 92.7%,the current efficiency was about 25.1%.The surface area ratio of cathode to anode was controlled to control the current density,and the electrode potential was transferred to the potential that facilitates the conversion of nitrate to nitrogen during the electrolysis process.The area ratio of cathode to anode was controlled so that the cathode potential was about-0.9 v,and the best way to reduce nitrate nitrogen to nitrogen was found.The first thing that happens is that NO₃^--N is reduced to NO₂^--N,and NO₂^--N is rapidly converted to NH₄⁺-N.At the same time as the cathode reaction,the generated NH₄⁺-N migrates to the anode.Under the condition of Cl^-,ammonia nitrogen was converted into nitrogen near the anode,which realized the removal of nitrate nitrogen in the electrolyte and harmless product.