Quick assessment of the photocatalytic activity of TiO2 construction materials by nitroblue tetrazolium (NBT) ink

Abstract The photoactivity of TiO 2 -bearing construction materials was assessed with nitroblue tetrazolium (NBT) ink. The photocatalytic reaction was monitored with UV–vis diffuse reflectance spectroscopy, colorimetry and digital image processing. The results delivered by the three datasets were linearly related, even though the experimental setup was inexpensive and involved only handheld instruments. The NBT reduction and ISO 22197-1 oxidative NOx removal findings also proved to be acceptably linear, may, then, be promising alternatives to conventional NOx photocatalytic performance testing. The advantages of the procedure proposed over conventional testing include convenience of use, time savings, in-situ applicability, readily distinguishable colour change and low cost.