Comparison of Acid Orange 7 Degradation in Solution by Gliding Arc Discharge with Different Forms of TiO_2

摘要

Plasma catalysis for wastewater treatment is an emerging advanced oxidation process. In the present work, the performances of photocatalyst nanoparticles-assisted and immobilized photocatalysts-assisted gliding arc discharge (GAD) plasma reactors have been tested with the acid orange 7 (AO7) solution selected as the target wastewater. Immobilized photocata-lysts of γ-Al_2O_3-TiO_2 were made by a sol-gel and immersion method with activated alumina balls used as carriers. Through the analysis of XRD, it was found that TiO_2 surface was mainly anatase crystal-based. Compared with TiO_2 nanoparticles, the immobilized catalysts did not have the defects of inhibiting GAD which catalysts would be caused by suspended, therefore, showing a better catalytic performance. In the available range of dosage of catalysts, the catalytic effect of γ-Al_2O_3-TiO_2 was increased with dosage. When the catalyst amount was 10.0 g, COD of the target solution decreased with a rate constant of 0.0487 min~(-1) and an abatement rate of 39.2% in 40 min with TiO_2 nanoparticles (0.375 g · L~(-1)) as catalysts, but was decreased with a rate constant of 0.0573 min ~(-1) and an abatement rate of 43.6% in 40 min with γ-Al_2O_3-TiO_2 as catalysts. The system of plasma and γ-Al_2O_3-TiO_2 catalysts is suitable for high concentration organic wastewater treatment and, moreover, can degrade and mineralize wastewater effectively.