Feasibility of light-emitting diode uses for annular reactor inner-coated with TiO_2 or nitrogen-doped TiO_2 for control of dimethyl sulfide

摘要

Limited environmental pollutants have only been investigated for the feasibility of light-emitting diodes (LED) uses in photocatalytic decomposition (PD). The present study investigated the applicability of LEDs for annular photocatalytic reactors by comparing PD efficiencies of dimethyl sulfide (DMS), which has not been investigated with any LED-PD system, between photocatalytic systems utilizing conventional and various LED lamps with different wavelengths. A conventional 8 W UV/TiO_2 system exhibited a higher DMS PD efficiency as compared with UV-LED/TiO_2 system. Similarly, a conventional 8 W visible-lamp/N-enhanced TiO_2 (NET) system exhibited a higher PD efficiency as compared with six visible-LED/NET systems. However, the ratios of PD efficiency to the electric power consumption were rather high for the photocatalytic systems using UV- or visible-LED lamps, except for two LED lamps (yellow- and red-LED lamps), compared to the photocatalytic systems using conventional lamps. For the photocatalytic systems using LEDs, lower flow rates and input concentrations and shorter hydraulic diameters exhibited higher DMS PD efficiencies. An Fourier-transformation infrared analysis suggested no significant absorption of byproducts on the catalyst surface. Consequently, it was suggested that LEDs can still be energy-efficiently utilized as alternative light sources for the PD of DMS, under the operational conditions used in this study. Contrast to the photocatalytic decomposition (PD) efficiency, the ratios of PD efficiency to the electric power consumption were rather higher for the photocatalytic systems using UV- or visible-LED lamps, except for two LED lamps (yellow- and red-LED lamps), compared to the photocatalytic systems using conventional lamps.