Evaluation catalytic performance of Ag/TiO₂ in dielectric barrier discharge plasma

Dielectric barrier discharge (DBD) plasma technology combined with Ag/TiO2 composites for phenol degradation was investigated. The TEM, XRD, XPS results showed that Ag was successfully doped on TiO2. PL results indicated that the doped Ag on TiO2 obviously decreased the recombination rate of electron-hole pairs. The effect of silver loading, Ag/TiO2 introduction dosages, initial phenol concentration, applied voltage on Ag/TiO2 catalytic performance were also studied and analyzed. With introduction of 0.2 g L-1 0.5 wt% Ag/TiO2, the phenol removal efficiency was enhanced by 6% at 17 kV and 20 kV, the addition of Ag/TiO2 has slightly inhibiting effect on phenol degradation at 22 kV. The NO2- and NO3- concentrations were also measured by IC. The results showed that NO3- -N concentration reached 37 mg L-1 at 22 kV, and NO3- -N obviously decreased from 37 mg L-1 to 25 mg L-1 and NO2- -N increased from 0.10 mg L-1 to 0.24 mg L-1 with adding Ag/TiO2. The reason of inhibiting effect of Ag/TiO2 at 22 kV could be that the NO3- from discharge was involved in Ag/TiO2 catalytic reaction, and the reduction of NO3- could inhibit the electrons transfer from the Ag metal to O2, resulting in the lower phenol removal efficiency.