Green in-situ synthesis of TiO2 in combination with Curcuma longa for the tailoring of multifunctional cotton fabric

The introduction of green chemistry has become urgent in the development of innovative, high-performance functional textiles to reduce the environmental footprint of their production. This study aims to develop a new eco-friendly process for the hydrothermal in-situ synthesis of TiO2 in cotton fabric and dyeing with curcumin natural dye to produce a photocatalytically active coloured textile platform with simultaneous UV protection properties. Two approaches were developed: classical, which included dyeing of the cotton samples with Curcuma longa (turmeric) extracts at different concentrations (5 g/L, 10 g/L and 15 g/L) and subsequent hydrothermal in-situ synthesis of TiO2 in the presence of the dyed cotton samples, and greener, in which simultaneous dyeing with turmeric extracts and hydrothermal in-situ synthesis of TiO2 were carried out. Since increasing the turmeric concentration hindered the photocatalytic performance of TiO2 in the chemically modified cotton samples, 5 g/L was selected as the most suitable turmeric concentration. A comparison of the chemical modification processes shows that the simultaneous dyeing of cotton with turmeric extract and hydrothermal in-situ synthesis of TiO2 was beneficial and resulted in a UV protection factor 50+, which corresponds to excellent protection category. The photocatalytic activity of TiO2 was maintained in the presence of turmeric, indicating the compatibility of both players in the chemically modified cotton, but not the creation of a turmeric–TiO2 heterojunction with visible-light-driven photocatalysis. The presence of TiO2 inhibited the photodegradation of the curcumin dye, further confirming the compatibility of the two players.