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Eco friendly, biodegradable functionalized polyacrylamide/graphite composites have been used to adsorb synthetic dye from aqueous medium. The polymer composites have been synthesized and characterized with FT-IR, 1H and 13C NMR. The composite's adsorptive features have been analyzed using different parameters. The efficiency of adsorption process is determined using kinetic, equilibrium and thermodynamic analysis. The equilibrium uptake capacity was obtained from Langmuir, Freundlich, Tempkin and Dubinin-Radushkevich models. The correlation coefficients indicate that the Langmuir model show satisfactory fit for the uptake of dye. The adsorption process follows pseudo second order in addition to intraparticle diffusion model with a good correlation coefficient. The thermodynamic parameters ΔG, ΔH and ΔS show that the adsorption process is spontaneous (ΔG < 0), endothermic (ΔH > 0) and had decreased entropy (ΔS > 0). The equilibrium and kinetic experiments confirm that the temperature and pH play an important role i.e., the dye uptake increases with increased temperature and decreased pH. FTIR and desorption studies confirm the involvement of functional groups in adsorption mechanism. [ABSTRACT FROM AUTHOR]

In this work, the structural characterization and adsorption behavior of glucose and glucosamine grafted polyacrylamide/graphite composites (denoted as Gu-g-PAM/graphite and GA-g-PAM/graphite) were investigated. The grafted polymers were characterized by using Fourier transform infrared (FT-IR) spectroscopy, 1H nuclear magnetic resonance (NMR), 13C NMR and N2 sorption studies. The adsorption behavior of grafted polymers was compared by varying parameters such as pH, initial dye concentration, agitation time, adsorbent dose and temperature. The results showed that GA-g-PAM/graphite composite was an effective adsorbent for the uptake of acid violet 17 (Av-17) from an aqueous solution. The superior adsorption behavior was attributed to the presence of -NH2 and -OH groups in GA-g-PAM/graphite. Langmuir, Freundlich and Dubinin-Radushkevich (D-R) isotherms were used to describe the adsorption isotherm. The adsorption isotherm of the adsorbents fitted well with the Langmuir model with the maximum adsorption capacity (qo) of 78.13 mg/g for GA-g-PAM/graphite. The efficiency of adsorption with time was described using pseudo first-order, pseudo second-order and intra particle diffusion kinetic models. The kinetic study revealed that the adsorption equilibrium was attained within 50 min. The thermodynamic analysis stated that the adsorption of dye is spontaneous, physical and endothermic in nature. Desorption results revealed that all the adsorbents exhibit excellent stability and remarkable regeneration ability. [ABSTRACT FROM AUTHOR]

In this study, we prepared glucose and glucosamine-grafted polyacrylamide (PAM)/graphite composites as adsorbents and characterized by Fourier transform infrared (FT-IR), SEM/EDAX, XRD and TGA analysis. Direct blue 2b dye removal by composites was investigated using kinetic, equilibrium and thermodynamic studies by varying adsorption parameters. The results manifest that glucosamine-grafted PAM/graphite composite was an efficient adsorbent for the expulsion of dye from aqueous medium. The Freundlich isotherm fits well with the equilibrium data. The pseudo second-order model was suitable for describing the kinetic data and equilibrium attained within 60 min. Thermodynamic analysis reveals that adsorption of dye is physical, spontaneous and endothermic in nature. The recyclability study reveals that the regeneration efficiency of GA-g-PAM/graphite was maintained 85.35% up to eight cycles. [ABSTRACT FROM PUBLISHER]