s evaluated by the use of a self-cleaning and a de-pollution tests.
Degradation of soil and dirt under ultraviolet light was assessed by a colorimetric
method, the rhodamine B test [15,19,32–34]. Although rhodamine B test is a decoloration
analysis through colorimetric measurements, it is well known that in the
presence of TiO2 rhodamine B is not only decolorized but completely degraded.
Rhodamine B was chosen as a model organic dye since it is stable under UV illumination,
showing higher UV resistance in comparison with methylene blue [35],
another colorant widely used in self-cleaning experimental analyses