科研之友
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摘要
To investigate the effects of oxygen contents and surface area of the adsorbents on their removal efficiencies, poly(ethylene glycol) (PEG) with various molecular masses (200, 2,000, and 20,000) modified graphene oxide (GO-PEG) composites were fabricated and used for the removal of Pb(II) from aqueous solutions. The morphologies, specific surface area, and surface functional groups of the GO-PEG composites were characterized by field-emission scanning electron microscopy, Brunauer-Emmett-Teller method, thermogravimetric and differential thermogravimetric analyses, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and Raman spectroscopy. Batch experiments were conducted to evaluate the effects of contact time, initial concentration, adsorbent dosage, and temperature on the adsorption efficiencies of the adsorbents. The experimental data indicated that the adsorption of Pb(II) onto GO-PEG composites fitted well to the pseudo-second-order kinetic model and the Langmuir isotherm model. Thermodynamic studies indicated that the adsorption was a spontaneous and endothermic process. The obtained GO-PEG (200), GO-PEG (2000), and GO-PEG (20000) composites exhibited the maximum adsorption capacities of 204.50, 72.73, and 196.46 mg g(-1) toward Pb(II), respectively. The higher adsorption capability of GO-PEG (200) toward Pb(II) could be attributed to its relatively higher oxygen content and larger SSA. The adsorption capacities of GO-PEG (200) toward other metal ions including Cu(II), Cd(II), Mn(II), Er(III), and Y(III) were 48.04, 80.48, 36.1, 23.1, and 12.2 mg g(-1), respectively.
