The influence of TiO2 and N-TiO2 nanopowders in natural leather finishing for heritage or modern binding

The methods for processing raw hides over time, have been numerous: smoke, fat, fermented milk, egg, volcanic soils, plants (shells, fruits, leaves) and so on. The books binding with leather has its origins in the Orient and are known various types of goatskin and calfskin, tanned with sumac finished marbled (sapphire), in black (Moroccan), by floating and dyeing in various colors (Cordoba leathers). Preoccupations regarding the assurance of optimal characteristics for the binding leathers, respectively the durability of the leathers for the restoration of the patrimony objects or of the modern binding were of the most topicality in the last decades, abroad and also in our country. The paper describes the finishing of vegetable and alum tanned leather samples that have been functionalized with titanium dioxide (TiO2) or nitrogen-doped titanium dioxide (N-TiO2) nanopowders, in different concentrations. To simulate soiling in real conditions, four types of soiling agents were applied: tea, coffee, beetroot extract and pen paste. The samples were exposed to irradiation in a photoreactor with various light sources for up to 192 hours. The evaluation of the photocatalytic degradation was performed by the CIELab technique.