Experimental study on sodium persulfate denitrification based on hydrodynamic cavitation

Abstract

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.

Keywords

• hydrodynamic cavitation
• sodium persulfate
• denitrification
• ship exhaust gas