Molecular dynamics simulation of the effect of pH on the adsorption of rhodamine laser dyes on TiO2 hydroxylated surfaces

Said Hamad (1, 2) , Juan Ramon Sanchez Valencia (3) , Angel Barranco (3) , Jose Antonio Mejias (2) , Agustin R González-Elipe (3)

1 Institute of Materials Science of Seville, CSIC - University of Seville
2 Department for physical, chemical and natural systems
3 Universidad de Sevilla = University of Seville

We have carried out a study of the adsorption, on the (101) surface of anatase TiO2, of two industrially relevant rhodamines molecules (rhodamine 6G and rhodamine 800) employing Molecular Dynamics. These theoretical studies have shown that Rhodamine 6G must adsorb on surfaces under basic conditions. Moreover, the adsorption of this molecule shows a strong dependence upon the pH of the system, i.e. under neutral conditions the adsorption energy is quite smaller, and under acidic conditions the even lower adsorption energy indicates that there must be very little adsorption under such conditions. By contrast, for rhodamine 800 there is little dependence of the adsorption energy upon the pH, being expected that the amount of adsorption of this molecules is little affected by this parameter. These theoretical results are in qualitative agreement with the experimental results.

Mots clés: Physical Sciences

Said Hamad, Juan Ramon Sanchez Valencia, Angel Barranco, Jose Antonio Mejias, Agustin R González-Elipe. Molecular dynamics simulation of the effect of pH on the adsorption of rhodamine laser dyes on TiO2 hydroxylated surfaces. Molecular Simulation, 2009, 35 (12-13), pp.1140-1151. ⟨10.1080/08927020903108083⟩. ⟨hal-00530458⟩