Photocatalytic degradation of the herbicide iodosulfuron by neodymium or nitrogen doped TiO2

TiO2-based photocatalysts doped with 10 wt.% Nd3+ or 1.8 wt.% nitrogen are synthesized by a sol–gel method using Ti-butoxide and Nd(NO3)3 or aqueous ammonia as starting materials. The resulting powder crystal structure, textural properties, morphology, IR, UV/Vis and X-ray photoelectron spectra are studied. The photocatalytic activity was tested for the degradation of herbicide iodosulfuron under UV, visible and sunlight irradiation and the results are compared with those obtained with a commercial Degussa P25 product. The influence of photocatalytic test conditions (such as aeration, type of water used as pollutantʹs dispersion medium, type of the illumination light) are investigated. The impact of catalyst ignition temperature and doping with Nd or N on the efficiency of the photocatalytic process are examined. The doping with 10% Nd affects the activity of the catalysts negatively. Doping with nitrogen has insignificant influence on the catalyst activity when ultra-pure water is used to dissolve the pollutant. However, the N-doped catalyst is much more effective when tap water is used. Using Degussa P25, 99% of the pollutant (dissolved in ultra-pure water) can be destructed after 20 min under UVA irradiation, whereas photolysis causes destruction of 74% of the pollutant in 150 min.