Nano ZnO/TiO2 photo-catalyst as an anti-ultra violet agent on Indigofera tinctoria colored cotton fabric

The application of Indigofera tinctoria as natural dyes in textile industries has its own limitation. Exposure to sunlight can promote color fading in the fabric because ultra violet (UV) rays contained in the sunlight can damage the chromophore group in dye structure, especially for natural dye which has less stability structure compared to the synthetic dyes. Nano ZnO/TiO2 photocatalyst is a semiconductor material which has band gap that proportional to the wavelength of UV rays. This property makes this material is suitable for UV absorber. This study aims to improve the resilience of Indigofera tinctoria dye towards UV rays by utilizing nano ZnO/TiO2 as an additive. Methods of this research include the manufacture of nano ZnO/TiO2 by sonication method carried out in atmospheric pressure at temperature of 30°C for 30 minutes. The obtained ZnO/TiO2 nanoparticle was diluted in ethanol and applied on Indigofera tinctoria colored cotton fabric using simple dipping method. The independent variables in this study were variation of ZnO/TiO2 weight ratio (20, 21 and 22%), time of sonication ZnO/TiO2 (10, 20 and 30 minutes), and concentration of ZnO/TiO2 applied on fabric (75, 150, and 300 ppm). ZnO/TiO2 nanoparticle was characterized using X-Ray Diffraction (XRD) and Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy (SEM-EDX). Evaluation of dye degradation on Indigofera tinctoria dye fabric was done by color strength analysis. The data obtained was analyzed by Response Surface Method (RSM) assisted by minitab18 software. Optimum operation condition were found to be 20% ZnO in ZnO/TiO2, 30 minutes of sonication, and 300 ppm ZnO/TiO2. The results from this study showed that nano ZnO/TiO2 were successfully synthesized and could be a potential candidate as an additive to increase the color stability of the dye.