In Situ Synthesis of Chitosan-Grafted Polyacrylamide Loaded by TiO2 Nanoparticles for the Adsorption of Sirius Yellow K-CF from Aqueous Media: Isotherm, Kinetic and Thermodynamic Studies

Abstract

Toxic waste water and infected water are the considerable sources of environmental contaminations . Dyes as the source of toxicity of waste water are used in various industries like dyestuff, textile, paper, plastics and pharmaceutical. Recently, reactive dyes have been commonly used because of their advantages such as better dyeing processing conditions and bright colors. So, removal of dyes from effluents is so important. Among the materials used as the common adsorbents, chitosan and polyacrylamide are relatively cheap and the promising materials can be used as adsorbents. In the present study, TiO2 nanoparticles dispersed in chitosan grafted polyacrylamide matrix was synthesized by in situ method and used for the removal of Sirius yellow K-CF dye from aqueous solution. The synthesized nano-composite was characterized by FE-SEM, TEM, XRD and FT-IR. The effect of pH, adsorbent dosage, time and temperature were investigated. The results showed that the highest dye removal efficiency was happended in the acidic pH of 2 with 0.05 g of TiO2-PAA-Ch adsorbent. The equilibrium data were compatible very well with the Langmuir isotherm (qm=1000 mg/g, 96.81% of dye removal). The Dubinin-Radushkevich isotherm and thermodynamic studies proved that the adsorption process is physical, endothermic and spontaneous. Kinetic study verifies that pseudo second order kinetic model is the predominant model. In this study, TiO2 nanoparticles dispersed in polymer matrix was synthesized and employed for the removal of Sirius yellow K-CF from aqueous media. Electrostatic attraction between positive charges of adsorbent surface (NH3+) and molecules of anionic dye together with formation of hydrogen bond (Dye-NH3+) cause the adsorption of dye on PAA-Ch. On the other hand, Ti+4 in PAA-Ch structure can intract with the anionic molecules through the electrostatic adsorption. The results of this study interact that the new synthesized TiO2-PAA-Ch composite with high amount of NH2 functional groups and Ti+4 is an efficient adsorbent for an environmental applications to remove many contaminants, dyes and organic pollutants.