Experimental study on sodium persulfate denitrification based on hydrodynamic cavitation

  Objectives   In order to improve the efficiency of sodium persulfate (Na₂S₂O₈) wet oxidation denitrification and its utilization rate, wet oxidation denitrification experiments using hydrodynamic cavitation to enhance Na₂S₂O₈ are carried out.

  Methods   This paper explores the feasibility of using hydraulic cavitation to enhance Na₂S₂O₈ denitrification, and studies Na₂S₂O₈ solution temperature and concentration, chloride ions (Cl⁻) and other factors on denitrification effects and related mechanisms.

  Results   The experimental results show that the special environment created by hydrodynamic cavitation is beneficial for activating Na₂S₂O₈ and improving its denitrification efficiency, but the overall denitrification effect is insufficient. Under the experimental conditions, when the temperature increases from 30 °C to 80 °C, the nitrigen oxide (NO) removal rate increases from 7% to 43%, showing that increasing the concentration of Na₂S₂O₈ is beneficial for increasing the NO removal rate. Under high-temperature conditions, increasing the concentration of Na₂S₂O₈ has a more obvious promotion effect on improving the overall denitrification rate. The presence of Cl⁻ can greatly increase the NO removal rate. When the ratio of Cl⁻ concentration to Na₂S₂O₈ concentration reaches 0.15∶0.1, the NO removal rate reaches 94%.

  Conclusions   Hydrodynamic cavitation promotes the reaction rate of Na₂S₂O₈ to remove NO. Cl⁻ produces more oxidizing substances in the special reaction environment created by hydrodynamic cavitation, thereby improving the denitrification effect.