Enhanced photocatalytic activity of titania in the presence of KNO₃ on the photodegradation of dyes

Pristine TiO₂ nanoparticles were synthesized using the sol-gel method. Morphological and size distribution patterns of the photocatalyst were determined using transmission electron microscopy, scanning electron microscopy and Brunuer-Emmett-Teller (BET) technique. Raman spectroscopy and powder X-ray diffraction were carried out to yield structural composition of TiO₂. The photocatalyst was further used to photodegrade bromophenol blue (BPB) and methyl orange (MO), two anionic dyes, in the presence of KNO₃. The addition of KNO₃ improved the photodegradation of the dyes. The highest dye removal was observed after the addition of 5 mgL⁻¹ of KNO₃. The effect of pH upon the removal of the dyes was studied. Over 80% of BPB was removed, while 40% of MO was removed at pH 1. The results gave good correlation between radical-scavenging and improved photoactivity. Increased radical-scavenging effect was measured by the decrease of DPPH at 517 nm.