Determination of the photocatalytic activity of TiO2 with high adsorption capacity

Abstract

Photocatalysis is often used for the decomposition of organic compounds in water, e.g., for dye decomposition. There are many problems with calculating the photocatalytic activity of photocatalysts during dye decomposition, especially in the case of photocatalysts with a high adsorption capacity because it is difficult to say whether a dye is photocatalytically decomposed or whether it is only adsorbed on photocatalyst surface. In both cases, the dye disappears from the water, but the optimal situation is when the dye is both adsorbed and decomposed on photocatalyst surface. Moreover, it is problematic to compare the photocatalytic activity of different photocatalysts when they have strong adsorption capacity. In this study a new method of measuring photocatalytic activity of photocatalysts with high adsorption capacity is presented. Reactive Red (monoazo) and Direct Green (poliazo) dyes were used to determine adsorption capacity and photocatalytic activity of commercial TiO 2 Degussa P25, anatase TiO 2 and carbon modified anatase TiO 2 .

The Effect of pH and Aging Time on the Synthesis of TiO2 – Chitosan Nanocomposites as Photocatalyst by Sol-Gel Method at Room Temperature

“…Photocatalytic activity of TiO 2 is relatively high because of the wide band gap of energy. With the right source of light, TiO 2 photocatalyst generates electron and hole pairs to start a chemical reaction chain of pollutants demineralization (Janus et al, 2011;NguyenPhan and Shin, 2011).…”

Sonocatalytic Degradation of Humic Substances From Aquatic Environments Using MgO Nanoparticles

“…7 also shows that by increasing the contact time, the removal efficiency of humic substances was increased in all processes especially sonocatalytic processes. The high rate of sonocatalytic decomposition of humic substances due to the increase in the contact time could be attributed to the increased production of hydroxyl radicals as well as the increased formation of electron pores (23,24).…”

“…Due to their small size and unique surface characteristics, the use of nano-size catalysts for the decomposition of various bioenvironmental contaminants in different sonocatalytic processes has been taken into account (21,22). In various studies on sonocatalytic procedures, various semiconductors such as ZnO (zinc oxide) and TiO 2 (titanium dioxide) have been used as catalysts (16,19,23). In comparison with other existing catalysts, MgO as an alkaline earth metal oxide has been considered as a promising catalyst due to its remarkable features such as low cost, simple synthesis, and non-toxicity to the environment (especially aquatic environment) (24,25).…”

The role of adsorption in decomposition of dyes on TiO2 and N-modified TiO2 photocatalysts under UV and visible light irradiations

“…RR198 is strongly adsorbed on the surface of TiO 2 therefore after photocatalytic test, adsorbed and undecomposed RR198 was removed from the photocatalyst surface through the changing of pH of the solution. This technique was already reported by Janus et al [27]. In case of MB decomposition the tests were performed at different pH values.…”

“…Therefore, for accurate measurements of amount decomposed RR198, each time after photocatalytic process, desorption of adsorbed RR198 on the photocatalyst surface was carried out by simply change of pH solution. This procedure was already described by our group [27].…”