Development of a microwave-discharge light-emitting diode (MDLED): a novel UV source for the UV-driven microwave-assisted TiO2 photocatalytic treatment of contaminated wastewaters.

This brief article reports on the fabrication of a prototype novel semiconductor digital device, a microwave-discharge light-emitting diode (MDLED), consisting of an LED and a Schottky barrier diode encapsulated in a quartz ampoule. Coating the surface of this ampoule with TiO2 yielded a new photocatalytic TiO2 unit (MDLED-TiO2) for use in treating contaminated wastewaters. To the extent that this MDLED-TiO2 is driven only by microwave energy, there is no need for electric wires or electrical AC power. As much of the activity of TiO2 photocatalyst is enhanced and ultraviolet light emission is generated only by irradiating with microwaves, the MDLED-TiO2 affords a simple water treatment device as demonstrated in the present study. The digital device consisted of 14 pieces of MDLED-TiO2  units immersed into a model contaminated wastewater toward the decomposition of organic pollutants and sterilization of natural bacteria-contaminated wastewaters performed in an energy-saving manner simply by irradiating the wastewaters with microwaves.