Synthesis of high efficient CS/PVDC/TiO2-Au nanocomposites for photocatalytic degradation of carcinogenic ethidium bromide in sunlight

Ethidium bromide (EtBr) is one of the most broadly used dyes in molecular biology laboratories. It was considered a strong mutagenic, carcinogenic and possesses a major safety problem for the researchers and environmental hazards during the disposal process. In the current study chitosan (CS) and polyvinylidene chloride (PVDC) based on different morphologies of TiO2-Au nanocomposites were prepared, namely as CS/PVDC/TiO2-Au nanocomposites. Firstly, the titanium dioxide nanowires (TiO2-NWs, gold nanoparticles (Au-NPs) and TiO2-NWs doped by Au-NPs (TiO2-Au) were successfully fabricated and well-evaluated using X-ray diffractometer (XRD) and transmission electron microscope (TEM). Furthermore, chitosan was prepared from crabs shell wastes and blended with PVDC then different loadings of TiO2-Au nanocomposites were incorporated onto the nanocomposites films. The prepared CS/PVDC/TiO2-Au nanocomposites films were characterized using UV-Visible spectra, Fourier transforms infrared (FT-IR), XRD and TEM. Moreover, the CS/PVDC/TiO2-Au nanocomposites were used for photodecomposition of EtBr under sunlight irradiation from~ 400-600 W/m2 with and without aeration as well as assaying integrity of the EtBr after decomposition by horizontal gel electrophoresis. The results established that the CS/PVDC/TiO2-Au nanocomposites were sufficient to remove ~70-90 % of the EtBr through the irradiated time course and ~ 60 % of the dye was degraded in the first one hour.