The fabrication of pentaerythritol pillared graphene oxide composite and its adsorption performance towards metal ions from aqueous solutions

Pentaerythritol-modified graphene oxide (GO-PER) composite was prepared by an esterification reaction. The chemical composition and morphology of the GO-PER composite were characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric analysis, scanning electron microscopy, Brunauer-Emmett-Teller method, X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The GO-PER composite was used as an efficient adsorbent for the removal of Pb(II) from aqueous solutions. Batch experiments were conducted to assess the effect of pH, temperature and contact time on the adsorption of Pb(II) onto the GO-PER composite. The adsorption kinetics, isotherms, and thermodynamics of Pb(II) onto the GO-PER composite were discussed in detail. The experimental data were fitted well by the pseudo-second-order kinetics model and Langmuir isotherm model, and the maximum adsorption capacity of GO-PER for Pb(II) was 126.9 mg g(-1). Values of various adsorption thermodynamic parameters, such as Gibbs free energy (Delta G(theta)), entropy (Delta S-theta) and enthalpy (Delta H-theta), for adsorption of Pb(II) on CO-PER were calculated. Chemisorption was confirmed by FT-IR spectrum and XPS of CO-PER with adsorbed Pb(II). Thermodynamical study indicated that the adsorption of Pb(II) onto GO-PER was a spontaneous, endothermal, physical and monolayer process. The maximum adsorption capacities of GO-PER for trivalent lanthanum [La(III)], trivalent yttrium [Y(III)], trivalent erbium [Er(III)] and trivalent neodymium [Nd(III)] were 36.5, 32.375, 33.75 and 49.875 mg g(-1),respectively.