Three-dimensional porous graphene oxide-maize amylopectin composites with controllable pore-sizes and good adsorption-desorption properties: Facile fabrication and reutilization, and the adsorption mechanism

Three-dimensional (3D) porous graphene oxide-maize amylopectin (GO-MA) composites with controllable pore-sizes composites in the range of 6-40 nm were prepared by facile hydrothermal-assisted assembly approaches. The morphologies, pore sizes, specific surface area (SSA) and compositions of GO-MA(x:y) composites with and different GO-to-MA mass ratios (x:y) were characterized by scanning electron microscopy (SEM), N-2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). To reveal the adsorption-desorption mechanism, effects of contact time, temperature, initial adsorbate concentration, pH value of the solution on the adsorption process were studied in detail. The adsorption capacities of 3D GO-MA(20:1) composite for organic contaminants including tert-butyl hydroquinone (TBHQ), p-aminophenol (PAP), p-nitrophenol (PNP), o-nitrophenol (MNP), hydroquinone (HQ), alizarin red S (ARS) and neutral red (NR) were 22.17, 116.4, 44.78, 36.96, 16.10, 39.92 and 24.23 mg g(-1), respectively. The adsorption capacities of GO-MA(30:1) composite for inorganic substances including Pb2+, Mn2+, Cr2O72-, Cd2+, Cu2+, Nd3+, La3+, y(3+), Yb3+ and Er3+ were 84.76, 7.92, 13.6, 17.64, 30.56, 25.52, 12.48, 16.96, 23.32 and 30.32 mg g(-1), respectively. In addition, GO-MA(x:y) composites also exhibited high mechanical properties and good reusability. Consequently, GO-MA(x:y) composites could be used as reusable adsorbents for removal/enrichment inorganic/organic substances in aqueous solutions.