Hydrothermal fabrication of novel three-dimensional graphene oxide-pentaerythritol composites with abundant oxygen-containing groups as efficient adsorbents

Three-dimensional (3D) graphene oxide-pentaerythritol (GO-PER) composites with abundant oxygen-containing functional groups (such as carboxyl, hydroxyl, carbonyl, epoxy) were successfully prepared by a hydrothermal self-assembly method. The enrichment performances of GO-PER composites for rare earth elements (REEs) and phenols were investigated by batch adsorption experiments. The adsorption of REEs and phenols could reach equilibrium in 30 min and 60 min at room temperature, respectively. Furthermore, GO-PER composites exhibited excellent pH stability. The adsorption capacities of GO-PER composites were 27.92, 30.44, 43.2, 48.08 and 52.4 mg g(-1) for La3+, Y3+, Nd+, Er3+ and Yb3+, respectively. The adsorption capacities of GO-PER composites for phenols including 3-nitrophenol, hydroquinone and tent-butylphenol (TBHQ) were 61.1, 42.35 and 29.76 mg g(-1), respectively. Scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) specific surface area (SSA) analysis and Zeta potential analysis were used to characterize the physicochemical properties of the samples and propose the adsorption mechanism. The adsorption of REEs by GO-PER composites might be due to electrostatic attraction and surface complexation, while pi-pi stacking interaction and hydrogen bonding mainly contributed to the adsorption of phenols. Recycling experiments showed that GO-PER composites possessed excellent reusability and high stability. The as-prepared GO-PER composites could be potentially used to efficiently enrich or remove REEs and organic substances in aqueous solutions.