Formation of Active Species and Degradation of Bromamine Acid by Gas-liquid Electrical Discharge in Different Atmospheres

摘要

This study investigated the formation of different active species (·OH, H2O2, O3) in aqueous solutions using needle-plate gas-liquid discharge non-thermal plasma (NTP) with different atmospheres (air, argon, and oxygen). The changes in the pH and conductivity of a blank solution with different discharge atmospheres were also investigated. The degradation of the model compound, bromamine acid (BAA), in an aqueous solution was investigated. The effects of different factors on the BAA degradation were studied, including the types of discharge atmospheres, initial BAA concentration, and initial pH. The experimental results showed that, after a 60-min treatment, approximately 90.86%, 68.99%, and 49.96% of BAA was removed by plasma with oxygen, air, and argon discharge atmospheres, respectively, and input discharge powers of 49.23 W, 41.49 W, and 16.17 W, respectively. The BAA removal rate was lowest with an argon discharge atmosphere; however, the energy yield with argon was 1.73 and 1.6 times those with air and oxygen, respectively. The plasma degradation of BAA fitted the pseudo-first-order kinetic model. Compared to oxygen and argon, the initial concentration had little effect on the degradation of BAA when air was introduced into the reaction system. UV–vis absorption spectra of the BAA solutions were measured to illustrate the discharge degradation mechanism. No new peaks appeared in the UV–vis analysis of the BAA solution after the 60-min treatments. Therefore, the results essentially demonstrate that NTP is a suitable alternative method for the degradation of organic pollutants.