In this thesis, the novel nanocomposites (NC) based on poly(vinyl alcohol) (PVA) and modified ? -MnO 2 nanorods were prepared through solvent-casting technique with the assistance of ultrasonic irradiation for the removal of water pollutants such as lead ions and methyl orange. To achieve a good dispersion and uniform distribution of ? -MnO 2 nanorods and their more compatibility with polymer matrix, the surface of synthesized ? -MnO 2 nanorods was modified with L -valine, KH550, and stearic acid. The modified and unmodified nanorods were investigated with the different techniques such as FT-IR, XRD, EDX, FE-SEM, TEM, and TGA. Then, due to good film forming ability of PVA, their NC films were prepared and identified by different methods. Subsequently, the effect of modified nanorods on mechanical and thermal properties of PVA was studied. The results showed that thermal stability and tensile properties of NCs containing modified nanorods were improved comparison with pure PVA and PVA NCs containing unmodified nanorods. These properties increased with increasing amounts of modified ? -MnO 2 nanorods. Also, FE-SEM and TEM images exhibited a homogeneous dispersion of modified ? -MnO 2 nanorods and a good compatibility with PVA matrix. Crosslinked NCs with glutaraldehyde (GA) were prepared in order to investigate their application as the adsorbent for the removal of lead ions and methyl orange from aqueous solution. The GA was used to prevent the dissolution of PVA in aqueous solution as well as its easy separation. Efficient factors on adsorption process, including the initial concentration of the pollutant, pH, adsorbent amount, time and temperature were investigated. The obtained data showed that PVA-GA/ ? -MnO 2 - L -valine and PVA-GA/ ? -MnO 2 -KH550 have the high potential for lead ions adsorption from aqueous solution and PVA-GA/ ? -MnO 2 -stearic acid is an efficient adsorbent for the adsorption of methyl orange. The adsorption process exhibited a high dependency on the pH value. The study of adsorption isotherms indicated that Freundlich model was more suitable for describing the adsorption equilibrium and physical adsorption mechanism including electrostatic interaction play a dominant role in the adsorption mechanism. The adsorption kinetics study demonstrated that pseudo-second-order model was the best fit with the experimental data which proposes chemical adsorption mechanism, as well. The maximum lead ion adsorption capacity was 147.06 and 153.84 mg g -1 for PVA-GA/ ? -MnO 2 - L -valine and PVA-GA/ ? -MnO 2 -KH550 adsorbents, respectively. The maximum adsorption capacity of methyl orange was estimated to be 104.17 mg g -1 for PVA-GA/ ? -MnO 2 -stearic acid adsorbent. Thermodynamic investigations confirmed that the adsorption process was spontaneous and exothermic along with decreasing randomness for PVA-GA/ ? -MnO 2 - L -valine and PVA-GA/ ? -MnO 2 -stearic acid adsorbents, and endothermic along with increasing randomness for PVA-GA/ ? -MnO 2 -KH550 adsorbent.