Degradation of rhodamine B using an unconventional graded photoelectrode with wedge structure.

A graded TiO(2)/Ti round disk photoelectrode with a wedge structure is proposed, fabricated, and used in a rotating disk photoelectrocatalytic (PEC) reactor for the first time. In addition to improved light utilization efficiency resulting from multiple reflections of radiation light on the wedge surface, enlarged surface area enables the electrode to carry more pollutants for treatment. Compared with the conventional planar electrode with same diameter, the wedge-surface electrode showed much lower light reflectivity (<0.014 versus 0.306), larger photocurrent and better treatment performance. For model dye wastewater containing Rhodamine B (RB) at concentrations ranging from 20 to 150 mg · L(-1), wedge-surface electrode removed 100-79% total color in 60 min and 93-28% COD in 150 min, much higher than 69-28% and 50-4% obtained using the planar electrode under the same experimental conditions. Experimental results demonstrated that the wedge-surface electrode works efficiently and has great potential for treating high concentration dye wastewater.