Photocatalytic decomposition of aspartic acid over bare and silver deposited TiO2

Photodegradation of aspartic acid over UV irradiated bare and silver deposited titanium dioxide was investigated. It has been demonstrated that the nitrogen content of the amino acid is converted dominantly into NH3 (detected as NH4+). The evolution of CO2 was also measured. Both of these processes resulted in a considerable increase of pH in the liquid phase of the reaction mixture providing significant change in the reaction mechanism. Under prolonged irradiation NH4+ is oxidized through NO2− intermediate to NO3−. The primary steps of the mechanism of photodegradation are analyzed and described considering the results of competitive kinetic studies performed by using oxalic acid as efficient hole scavenger, coumarin as OH scavenger and various bare and silver deposited titanium dioxide.