The photodegradation of dyes under visible light irradiation represents an important step in the study of advanced oxidation processes (AOP). The sensitization of dyes and surface modification of titanium dioxide with adsorption of dyes promote the electron transfer from excited dyes to the conduction band of semiconductor, optimizing and accelerating the dye degradation. In this direction, we report the use of an anionic surfactant (sodium dodecyl sulphate) which promotes the dimerization of rhodamine B and subsequent adsorption on the TiO2 surface. As a result, it is verified that extremely reduced concentration of titanium dioxide (2 x 10(-5) g/mL) is sufficient to provide the photodegradation of dye in scale of minutes. (C) 2011 Elsevier B.V. All rights reserved.