Polyvinyl alcohol film comprising biochar modified titanium dioxide nanocomposites as decoloring and disinfectant agents

In this work, titanium dioxide nanowires were prepared hydrothermally in strong alkaline medium. In parallel, nanostructural biochar was obtained via carbonization of rice husk at relatively high temperature. Then, titanate nanowires were modified with the nanorods of biochar via in-situ and ex-situ approaches in order to determine the best way to produce the nanocomposites with improved properties. Polyvinyl alcohol was used as a commercial matrix to include the superlative nanocomposite obtained and casted as a free-standing nanocomposite film. The synthesized nanowires, nanorods, and their nanocomposites were intensively investigated with transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and N₂ gas sorption. The microscopic images confirmed successful preparation and modification of nanostructures. FTIR showed strong interactions between the surface functional groups of the obtained nanomaterials. XRD exhibited a reduction in the crystallite size upon the treatment step. Also, surface texture analysis of titanate nanowires displayed a significant enhancement, particularly in terms of surface area and total pore volume. These superior properties promote the obtained nanocomposites to be evaluated in the water treatment compared with the pristine. The results confirmed complete removal of methylene blue (20 ppm) from the synthetic wastewater within only 20 min. in dark either by using the nanocomposites as powders or even as films. Kinetics and isotherms indicated that the adsorption process obeyed Langmuir model and follows pseudo-second order. On the other hand, the prepared materials depicted a strong biocidal activity against pathogenic microorganisms. The obtained nanocomposites may open opportunities towards developed adsorbents with superior features and performance for applications in the field of water decontamination.