Degradation of Phenol in Water Using a Novel Gas-Liquid Two-Phase Dielectric Barrier Discharge Plasma Reactor

Phenol is toxic to human and persistent in the environment. Traditional treatment methods have the disadvantages of long treatment time, large amount of agents, and secondary pollution. In this study, a novel gas-liquid two-phase dielectric barrier discharge reactor was designed to remove phenol in aqueous solution. The effects of operating conditions (applied voltage, discharge spacing, pH, and conductivity), different water matrix (deionized water, groundwater, surface water, tap water), and inorganic ions were investigated. Moreover, the reaction mechanisms and the possible degradation pathway were proposed. The removal efficiency of phenol achieved 95.5% under the optimal operating conditions (discharge voltage of 17.6 kV, discharge gap of 1 mm, air flow rate of 60 mL min(-1)) coupling with H2O2 at 10 mM. The presence of different concentrations of inorganic ions (0.1, 1, 10, and 20 mM) could inhibit the phenol removal efficiencies. Specially, Cl- had different effects on phenol removal efficiency. The inhibition of Cl- on phenol removal was weakened when Cl- concentration was greater than 1 mM, which allows the technology that has certain advantages in treating high-salt wastewater containing high chloride concentration. In addition, (OH)-O-center dot was verified as the main active species in phenol removal. The possible degradation pathway was proposed according to theoretical calculation and GC-MS measurement.