In this thesis, the novel nanocomposites based on poly(vinyl alcohol) (PVA), starch, multi walled carbon nanotubes ( MWCNTs ) and carbon black (CB) were prepared with the assistance of ultrasonic irradiation for removal of methylene blue and methyl orange from aqueous solutions. To achieve uniform dispersion of MWCNTs and CB into PVA and starch, the surface of MWCNTs and CB were modified with ascorbic acid (AA). The modified MWCNTs and CB were investigated with the different techniques such as CHNS elemental analysis, fourier transform infrared spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis. Subsequently, the effect of modified MWCNTs and CB on the mechanical and thermal properties of PVA and starch was studied. The results showed that thermal stability and mechanical properties of PVA nanocomposites containing modified MWCNTs and CB were improved in comparison with pure PVA and thermal stability of starch nanocomposites containing modified MWCNTs was higher than that of pure starch. Also, FE-SEM and TEM images exhibited a homogeneous dispersion of AA-MWCNTs and AA-CB in the polymeric matrices. The prepared nanocomposites were used as adsorbents for removal of methylene blue and methyl orange from aqueous solution. Glutaraldehyde (Gl) was used in order to produce insoluble PVA based nanocomposites. The effect of initial dye concentration, pH, adsorbent amount, and time on the adsorption process was investigated. Also, the up-to-date linear and nonlinear forms of isotherms and kinetic models were studied. The obtained results showed that Gl-crosslinked PVA/AA-MWCNTs and Gl-crosslinked PVA/AA-CB nanocomposites have high potential for removal of methylene blue from aqueous solutions and starch/AA-MWCNTs nanocomposite is an efficient adsorbent for the adsorption of methyl orange. The adsorption of methylene blue by Gl-crosslinked PVA/AA-MWCNTs nanocomposite followed the nonlinear pseudo-first-order and linear Freundlich isotherm models. The experimental data for removal of methyl orange by starch/AA-MWCNTs nanocomposite fitted well with the nonlinear pseudo-second-order model and linear Freundlich isotherm. Also, the removal of methylene blue by Gl-crosslinked PVA/AA-CB nanocomposite obeyed the nonlinear pseudo-second-order model and nonlinear Freundlich isotherm. Gl-crosslinked PVA/AA-MWCNTs and Gl-crosslinked PVA/AA-CB nanocomposites can be reused for at least five times after regeneration without any loss of efficiency.
