Multi-dimensional optimization for a novel photocatalytic reactor incorporating the decolorization of azo dye and thermal management of ultraviolet light-emitting diode arrays

A high-power ultraviolet light-emitting diode (UV-LED) array is promising for dye decolorization. However, its practical application is limited by the heat dissipation efficiency of UV-LED. Hence, a coupling system combined with heat management of UV-LED arrays and great photocatalytic activity was proposed. In this work, multilayer wall-type active heat dissipation was first designed and compared from UV-LED beads irradiance, heat dissipation, and AR26 decolorization performance. Simulation and light intensity tests show that uniform arrangement, quincunX arrangement, and one-typed/rectangular arrangement are optimal for one, two, and three-layers system, respectively. Among these arrangements, the two-layer system shows the best performance compared with others, which owns the lower junction temperature (44 degrees C) and highest rate constant kapp (0.027 min-1). The effect of sewage temperature on photocatalytic performance under a two-layer system was further probed, and sewage with 20 to 40 degrees C is most beneficial to dye removal due to the trade-off relationship between light intensity and photocatalytic reaction rate. The life test verified the long-term stability of the coupling system, and only 15% luminous attenuation was reached after 85-day tests under high power conditions, which is much lower than that with conventional air cooling (35% reduction after 40-day tests). Our study paves the way to effectively use high-power UV-LED in dye wastewater treatments.