Degradation of alizarin red solution in DBD plasma
Non-thermal plasma processing using a dielectric barrier discharge(DBD)plasma was studied as a method for the degradation of the alizarin red,a kind of anthraquinone dye,dissolved in water.The effect of several parameters,such as discharging gap,input voltage and the pH values of solution,were investigated.The results showed that the DBD plasma could degrade the stubborn anthraquinone dye effectively.It was found that the concentration of alizarin red solution decreased to 0.26 mg·L-1 from an initial concentration of 100 mg·L-1 at the pH value of 8.4 in 40 min,while the concentration decreased to 1.61 mg·L-1 at the pH value of 5.8 and 5.70 mg·L-1 at the pH value of 7.0 in 45 min.It was also found that the optimum operation condition required a gap of 8 mm and an input voltage of 8 kV,which facilitated generating symmetrical discharging channels,the primary cause of degradation,as well as active species.The concentrations of O3 in the aqueous phase in the presence of buffer solution with different pH values were measured.Furthermore,the experimental results showed that the change of alizarin red concentration was related to the concentration of O3,an active species with strong oxidation ability,which was important to facilitate the breakdown of organic pollutant.