Abstract-

No abstract

Salicylic acid is used as a scavenger to quantify free hydroxyl radicals (•OH) produced from a cold plasma process. High-performance liquid chromatography revealed that salicylic acid was decomposed to 2,3-dihydroxybenzoic acid (2,3-DHB) and 2,5-dihydroxybenzoic acid (2,5-DHB). The concentrations of 2,3-DHB and 2,5-DHB were the highest when the concentration of salicylic acid was > 8,000 mg/L. Quantifying 2,3-DHB and 2,5-DHB concentrations revealed the association between the •OH concentration and the reaction time by using the following first-order equation: [•OH] = 0.01713t + 0.0311. Additionally, the rate of •OH formation in relation to different cold plasma conditions was also determined.

The degradation studies of picric acid (2,4,6-trinitrophenol, TNP) in water sample through a dielectric barrier discharge (DBD) of atmospheric air cold plasma was carried out. The used DBD reactor consisted of comprised two electrodes that were separated by using an insulating dielectric barrier having a electric discharge voltage varying from of 7.0 to 22.0 kV. The effects of the initial concentration of TNP on the initial degradation rate was investigated methodically. The initial degradation rate was determined experimentally by changing the initial concentrations of TNP between 91.02 and 210.17 mg/L using the DBD of cold air plasma. From experimental results, a kinetic equation for TNP degradation was established based on varying initial concentration as –R = 0.0252CTNP/(1+0.0076CTNP). When 0.0076CTNP << 1, the kinetics of TNP degradation complied with the pseudo-first-order reaction. For TNP degradation kinetics, such as ln (Ct/C0) = 0.0269t + 0.1605, ln (Ct/C0) = 0.0197t + 0.0792, and ln (Ct/C0) = 0.014t + 0.0623, the initial concentrations of TNP were 91.02, 153.3 and 210.17 mg/L, respectively. Moreover, the effect of initial concentration of TNP and the electric power on the degradation efficiency of TNP were determined.