The novel Cr(VI) anion-imprinted polymer(Cr(VI)-IIP) was prepared by a surface imprinting technique with bifunctional monomers pre-assembly system based on mesoporous silicon (SBA-15). The synthesized Cr(VI)-IIP was characterized by Fourier transmission infrared spectra (FT-IR), EDS, scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray powder diffractometer, N2 adsorption–desorption and thermogravimetric analysis (TGA), proving to be with a highly ordered mesoporous structure, as well as favorable thermal stability. The absorption characteristic of Cr(VI)-IIP followed the Langmuir adsorption isotherm model and the saturated adsorption amount was 96.32 mg/g at 25 °C – 2.7 times higher than that of non-imprinted polymer (NIP). Kinetic experiments showed that the adsorption behavior of Cr(VI)-IIP was in accordance with the pseudo-second-order kinetic model and reached the adsorption equilibrium state within 70 min. In addition, in the selectivity experiments, Cr(VI)-IIP exhibited strong specific recognition ability for Cr(VI) and could realize the separation of Cr(VI) and Cr(III) from an aqueous solution. The dynamic adsorption experiments exhibited that the dynamic adsorption efficiency of Cr(VI)-IIP was as high as 71.57%. Meanwhile, the dynamic regeneration experiments showed that the adsorption amount of Cr(VI)-IIP did not decrease significantly after repeating for five times. All of the findings suggested that Cr(VI)-IIP could achieve precise identification as well as efficient separation of Cr(VI) from aqueous solution.
In the present work, an excellent stable low graphene oxide/zinc oxide (LGO‐ZnO) composite membrane based on LGO nanosheets and ZnO nanonods has been successfully synthesized by vacuum filtration. The resultant graphene oxide nanosheet with a low degree of oxidation (LGO) was successfully prepared with the C/O ratio of 4.8 after stripped and oxidized. Importantly, the characterization results also demonstrated that ZnO nanorods were successfully intercalated into adjacent LGO nanosheets, rendering enlarged mass transfer channels, elevating hydration capacity and creating hierarchical nanostructures of membrane surfaces. Meanwhile, the stability of LGO‐ZnO composite membrane was enhanced obviously due to intercalation of ZnO nanorods, which was much more stable than that of LGO in aqueous solution. And it also exhibited outstanding permeation and separation performance for the water and various dyes solution system (with different concentration, volume or dye species), respectively. Accordingly, the permeate fluxes exhibited a drastic increase from 73 L/m2/h for LGO membrane to 1313 L/m2/h for LGO‐ZnO membrane. All the above results suggested that LGO‐ZnO membrane with high stability, high water permeability and favorable separation efficiency could be used as the great prospects membrane materials in separation of dyes from aqueous solution.
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