Self-cleaning coatings for sand stones

In this research, we tested the performance of the self-cleaning coatings based on exfoliated g-C3N4 applied on the surface of sandstone.Research activities include: i) preparation of exfoliated g-C3N4, ii) preparation of exfoliated g-C3N4 water suspensions, iii) application of the suspensions on the surface of the sandstone samples, and iv) testing of the self-cleaning performance.Exfoliated g-C3N4 was prepared by thermal exfoliation of bulk g-C3N4 prepared by thermal polycondensation of melamine.Samples were characterized using elemental analysis, infrared spectroscopy, scanning electron microscopy, the band gap values were determined with help of reflectance spectra measured using UV-VIS DRS spectrometry.Rhodamine B dye was used a model substance to evaluate the photodegradation activity of prepared samples, and the results showed significantly better photodegradation performance of exfoliated sample, which was further used for application on the surface of sand stone.Water suspensions of g-C3N4 (2 and 4 gdm -3 ) were prepared and applied on the surface of the sandstone samples using the spraying technique.Such prepared samples were subjected to the self-cleaning performance test based on the discoloration of rhodamine B under VIS irradiation and constant humidity and temperature.Changes in the a* coordinate in CIE L*a*b* color space were used to quantitatively monitor the discoloration of the tested samples.