Introduction of amine terminated dendritic structure to graphene oxide using Poly(propylene Imine) dendrimer to evaluate its organic contaminant removal

Abstract In this study, graphene oxide (GO) as one of the newest member of carbon materials with high specific surface area was modified using poly(propylene imine) dendrimer (PPI) with a regular and highly branched structure containing eight amine terminated functional groups. The transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscope (FESEM), energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), dynamic light scattering (DLS) and zeta potential analyzer were employed to characterize the new adsorbent. In order to demonstrate the adsorption capacity of this super adsorbent (GO-PPI), the removal of two anionic dyes (C.I. Acid Red 14 and C.I. Acid Blue 92) using GO-PPI was compared to graphite (G) and GO. Adsorbent dosage, pH, initial dye concentration and temperature were investigated as the parameters affecting the adsorption performance. Isotherm, kinetic and thermodynamic of dye removal was also studied. Langmuir isotherm and pseudo-second-order kinetic models well described the dye removal mechanism and adsorption rate, respectively. The spontaneous and exothermic nature of the adsorption process was demonstrated by negative values of Gibbs free energy ( ΔG ) and enthalpy ( ΔH ). The maximum adsorption capacity of G and GO was 169.49 and 9.302 mg/g, while the adsorption capacity of GO-PPI improved significantly to reach 434.78 mg/g.