engleski

Photoreactor design for UV-LED photocatalytic degradation of micropollutants

In this work, a photoreactor using 8 different arrays of UV-LED was simulated using Zemax Opticstudio software. The design of the light sources was based on the product RealUVTM UVA-LED strip lights, provided by Waveform Lightning. The reactor tested was a quartz cylinder of known dimensions coated with a nanolayer of TiO2 on its inner walls. The liquid inside the reactor was salt water. The LED strips were positioned in radially-symmetric distributed columns, illuminating the reactor from outside. The number of LED columns around the reactor (4 or 6), number of LEDs per column (6 or 12) and distance between the columns and the reactor (1 or 2 cm) were the parameters varied for the simulation. The light profile on the reactor’s walls and inside its middle cross section was evaluated. Results show that arrays with LEDs positioned closer to the reactor provided higher incident flux and radiance. However, a less homogenous distribution of light is observed for arrays closer to the reactor. Light homogeneity is a key parameter for an efficient photoreactor design, particularly for photocatalysis, since electron- hole recombination is enhanced in the areas with higher radiation intensities, decreasing the overall efficiency of the process. Doubling the number of LEDs on each column from 6 to 12 decreased homogeneity for all cases and did not improve the average values of radiance and incident flux per LED. Changing the number of columns around the reactor from 4 to 6 increased the light homogeneity on the reactor’s walls, but decreased it on the cross section. Considering the geometry of the reactor and the position of the catalyst on its inner walls, the light intensity on the cross section is fundamental to understand the pollutant degradation which comes from photolysis, while the light intensity and homogeneity in the reactor walls affects greatly the photocatalytic degradation. The most efficient photoreactor design should combine higher values of radiance and incident flux per LED with high homogeneity on the reactor walls.

AOP ; LED ; photocatalysis

nije evidentirano