Theoretical and experimental studies on the adsorption of intercalant dyes on anatase and rutile

The adsorption and photodegradation of acridine orange (AO) and acriflavine (AF) on two titania crystalline phases, anatase and rutile were experimentally studied and compared with results of a computational simulation. The adsorption capacity of rutile was higher than that of anatase, while the reverse is observed for the photodegradation of both dyes. The adsorption of AO on both adsorbents was higher than that of AF, which was related to the higher basic character of the dimethylammonium groups of AO in comparison with the amine groups of AF.Taking into account that the computational simulation was made in vacuum and the experimental results in an aqueous medium, the results of both approaches are general in agreement with each other. The heterogeneity of the adsorbent surface of rutile, the possible cause of the higher adsorbent capacity of rutile and higher catalytic capacity of anatase when compared are explained by the computational model. A factor that the computational simulation did not take into account was the macroporosity of rutile that could increase the apparent adsorption capacity.

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► We studied the adsorption of two intercalant dyes on anatase and rutile.
► Adsorption and photodegradation were studied experimentally and computationally.
► Different adsorption sites and dye molecule arrangements were simulated.
► Studied dyes were acriflavine and acridine orange.
► The origin of photodegradative efficiency of anatase and rutile is discussed