Optical Methylene blue absorbance in UV –Vis region with different UV irradiation times is shown in Fig. 1 Methylene blue (MB) decomposition of sputtered- TiO2 films increased as UV irradiation times
increased. MB , Azure B (AB) , Azure A (AA) and Phenotiazine (Pha) were decomposed coexistingly. Related to the present observations, blue shifs of the absorption bands seen during the photo oxidative N-demethylation was observed by Mohan-madand Morrison during “photodynamic therapy “ studies using visible light irradiation > 520 nm. N-dealkylation of dyes containing auxochromic alkylamine groups plays an important role in photocatalytic degradation.
The color of MB solutions becomes less intense ( hypsohromic effect ) when all or part of the
auxochromic groups ( methyl or methylamine ) degrade [3,4] . Moreover, on degradation process,
methyl group of MB were pull out ( N-demethylation) at the bond-site of N atom. These processes can change color of MB to be colorless (Fig.2) At the and,Methylene blue solution was changed to be HCl,H2SO4 HNO3, CO2 and H2O