In this project, the nanocomposite (NC) films based on poly(vinyl alcohol)(PVA) and modified TiO 2 nanoparticles () with antibacterial properties via ultrasonic irradiation and solution casting method were prepared and characterized with the different analysis. In first project, the surface of TiO 2 was modified with folic acid (FA) in order to improve the compatibility and dispersion of TiO 2 in the PVA matrix. Afterwards, the modified were characterized by different analysis such as Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Field-emission scanning electron microscopy (FE-SEM), transmittance electron microscopic (TEM), thermogravimetric analysis (TGA), Energy Dispersive X-ray (EDX). In the following, the modified with FA was added to the PVA matrix with different weight percentages and characterized with various analysis such as FT-IR, XRD, FE-SEM, and TEM. With the help of FE-SEM and TEM images, the uniform dispersion of modified TiO 2 nanoparticles was well visible in the PVA polymeric tissue. In the following, with the help of the TGA, it was found that the thermal stability of NC films increased compared to pure PVA polymer. In the study of the contact angle of the water with nanocomposite films, it was found that the addition of modified to the PVA matrix increased the hydrophilicity of NC films compared to pure polymer. In the study of optical properties, it was found that UV absorption by NC films was higher than pure PVA. In the survey of antibacterial properties of prepared NC films against Escherichia coli (E.coli ) and Staphylococcus aureus (S. aureus) as gram-negative and gram-positive bacteria samples respectively, it was found that in the presence of The UV irradiation, the produced NC films have more antibacterial properties than pure PVA. In the second research project, PVA/TiO 2 -FA NC films were used as adsorbents for the removal of toxic and dangerous congo red dye. Initially, in order to insolubilize PVA NC films in aqueous solution, glutaraldehyde was used as a crosslinker agent to cross-link the NC films. Then the cross-linked NC films were characterized by different analysis such as FT-IR, XRD, TGA, BET, and FE-SEM. In the following, the effective factors on adsorption, such as pH, amount of adsorbent, time, initial concentration and temperature, were investigated in the adsorption process. In the study of isotherm behavior, it was found that adsorption behavior in this project is more agreement with the Langmuir model and the adsorption mechanism is a chemical adsorption type. In kinetic behavior, it was found that the adsorption behavior follows a pseudo-second-order kinetic model. Thermodynamic investigations confirmed that the adsorption process was spontaneous and exothermic with decreasing irregularities.