Yield of hydrogen peroxide, ozone and nitrite nitrogen with DBD arrays in water mist spray

Summary form only given. Electric discharge in water can accompany UV radiation and electron impact, and can generate oxidants such as hydroxyl radicals, ozone and hydrogen peroxide. Here, a non-thermal plasma processing system was established by means of dielectric barrier discharge (DBD) arrays in water mist spray. The yield of hydrogen peroxide (H₂O₂), ozone (O₃) and nitrite nitrogen (NO_x) were both enhanced after discharge in water. The effects of water-air flow ratio, discharge time and high voltage power were investigated. The intensities in the ultraviolet region were measured by optical emission spectroscopy (OES) with different power input and moisture content. Experimental results show that there exist intense emissions of OH (309-317.8 nm), O⁺ (372.3, 375.1, 394.7, 397.6 nm), N₂ (335.5, 352.1 nm), and NO (296, 357.7, 378.9 nm) in the plasma and the intensity increases with both increasing input power and moisture. The concentration of H₂O₂, O₃ and NO_x was measured after discharge. The yield of H₂O₂, O₃ and NO_x in water and O₃ and NO₂ in DBD changed as a function of water-air flow ratio and treatment time. For same treatment time, the yield of O₃ and NO₂ in the DBD increased initially and then decreased with increasing water-air flow ratio, and the yield of H₂O₂, O₃ and NO_x in water decreased slowly with increasing water-air flow ratio. For same water-air flow ratio, the yield of O₃ and NO_x in water increases initially then remains constant with increasing treatment time; the yield of H₂O₂ in water increases significantly and sustained with increasing treatment time, and the pH value of treated water slightly decreases with increasing treatment time. The experimental results- were fully analyzed by the chemical reaction equations and commented by the physical principles as much as possible. Finally, the water containing phenol was tested in this system. The degradation rate came to 86% in 30 min.