A calibrated UV LED light source for photocatalytic experimentation

Photocatalysis is an evolving field that has a potential to become a cost effective water cleaning method. One of the most studied photocatalysts is Titanium Dioxide (TiO2). It has a high activity in response to UV wavelengths but almost no activity in the visible region of the spectrum. The activity changes rapidly between roughly 340 and 370 nm although this can be modified by doping. This region of the spectrum corresponds to the current lower limit of high efficiency LEDs. This presents a challenge in the use of UV LEDs for commercially viable photocatalysis and makes accurate comparisons of experimental data between different research groups essential. This paper presents a photocatalytic test reactor that provides a calibrated light source and pre-defined test conditions to remove as many sources of uncertainty as possible to improve data comparability. The test reactor provides a selectable intensity of up to 1.9 kW/m2 at the photocatalyst surface. The comparability of the results is achieved through the use of pre-calibration and control electronics that minimizes the biggest source of uncertainty – intensity variation between individual LEDs. The system devised reduces the intensity variation between systems by a factor of 11.6.