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

Abstract

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.

Keywords: 2,4-Dichlorophenoxyacetic acid; Escherichia coli; Microwave-UV photodegradation; Microwave-discharge light-emitting diodes; Photocatalyst; Wastewater treatments.