Theoretical study on adsorption characteristics and environmental effects of dimetridazole on TiO2 surface

Abstract

In this paper, the adsorption characteristics of dimetridazole on anatase TiO2(1 0 1) and (0 0 1) crystal surfaces has been studied by using density functional theory. Adsorption structures of dimetridazole on anatase TiO2(1 0 1) and (0 0 1) crystal surfaces have been optimized under vacuum, water, acidic and alkaline conditions, respectively. The optimum adsorption site, adsorption energy and the electronic structure of the stable adsorption model were calculated. By analyzing the optimal adsorption site, we found that the possibility of degradation of dimetridazole on the surface of TiO2 and reaction site of degradation were the opening ring of CN bond on the imidazole ring. By comparing the adsorption characteristics of dimetridazole on two different crystal planes of TiO2 under acidic and alkaline conditions, we found that the adsorption wavelengths of electron transition between conduction bands and valence bands of dimetridazole on anatase TiO2(1 0 1) crystal plane are within the range of visible wavelength. The results show that TiO2(1 0 1) can effectively utilize visible light and catalyze the adsorption and degradation reaction of dimetridazole on TiO2(1 0 1) surface. Our results show that TiO2(1 0 1) crystal surface can effectively use visible light under acidic and alkaline conditions. Our conclusion can explain the experimental result that the use of visible light on TiO2(0 0 1) face is greatly affected by the environment.