Electrochemical production of ammonium persulfate using absorption solution from ammonia-based wet desulfurization and denitrification

The resource recycling of flue gas pollution is the developing direction of exhaust pollutant treatment. In order to explore the feasibility of the direct electrolysis process for resource recycling of the absorption solution from the ammonia-based wet desulfurization and denitrification, the effect of electrolyte compositions and concentrations, temperature, current densities, flow rate, electrolytic time and impurities of absorption on current efficiency of persulfate production were investigated in a two-compartment electrolytic cell under batch recirculation. The experimental results indicated that urea and ammonia has inhibitory effect on current efficiency, while ammonium sulfite and nitrite existing in anode chamber showed no significant influence on current efficiency. The current efficiency of simulated absorbent solution decreased to 69.88%, which was much lower than 86.98% by the pure ammonium sulfate electrolysis process under the optimal condition. Therefore, necessary pretreatments for the absorption solution, which contained the removal of heavy metal ions and urea, the oxidation of sulfite and the adjustment of pH, must be adopted before entering the electrolysis system. Using the pretreated absorption solution, the current efficiency could reach to 85.12%. The electrolytic reactor could effectively produce persulfate in anodic chamber and hydrogen by-product in cathodic chamber at the same time. Furthermore, the remainder solution after crystallization could be coupled with circulation absorption solution, and thus improving the denitrification efficiency. Therefore, it is a novel environmentally effective technology for flue gas cleaning with great prospects for development. © All Right Reserved.