Fabrication of ACF/GO/PEI Composite for Adsorption of Methyl Orange from Aqueous Solution.

ACF/GO/PEI (activated carbon fiber/graphene oxide/polyethyleneimine) composite was fabricated by crosslinking reaction and characterized with Scanning electron microscope (SEM), N2 physical adsorption and Fourier transform infrared spectroscopy (FTIR). Furthermore, the adsorption behavior of ACF/GO/PEI composite for methyl orange (MO) from aqueous solution was investigated. The experimental results showed that the specific surface area of ACF/GO/PEI composite is 1013.6 m2/g and almost the same as that of original ACFs. However, with a larger fraction of mesopores, the pore structure of ACF/GO/PEI composite showed a significant change in comparison with that of original ACFs. Accordingly, ACF/GO/PEI composite indicated more excellent adsorptivity than ACFs. The tests also showed the adsorption capacity decreased with the increase in adsorbent mass and pH. The adsorption isotherm was fitted using both Langmuir and Freundlich adsorption models and the adsorption process was found to be well-described by Langmuir model. Moreover, the adsorption kinetics was discussed with pseudo-first-order, pseudo-second-order and intra-particle diffusion models and the results disclosed the kinetic data were well fitted with pseudo-second-order kinetic model and the adsorption rate was controlled by intra-particle diffusion and film diffusion. Thermodynamic parameters including ΔG, ΔH and ΔS showed that the adsorption process was a spontaneous, endothermic and increasing randomness process.