Preparation of α-zirconium phosphate-pillared reduced graphene oxide with increased adsorption towards methylene blue

• α-Zirconium phosphate (ZrP) pillared reduced graphene oxide (rGO) was prepared.
• rGO–ZrP possessed a higher BET specific surface area than rGO.
• The reunite of rGO–ZrP was interrupted by ZrP during storage.
• The maximum adsorption capacity of MB onto rGO–ZrP was ∼1.38 g/g at 30 °C.
• Adsorption-desorption efficiency of rGO–ZrP remained constant after six cycles.

In order to prevent the reunion of reduced graphene oxide (rGO) during storage, α-zirconium phosphate (ZrP) was used as the modifier, and a peculiar adsorbent of ZrP–pillared rGO (rGO–ZrP) was prepared. The features of rGO–ZrP were characterized by using Fourier transform infrared (FTIR), scanning electron microscope (SEM), transmission electron microscopy (TEM), energy dispersion X-ray (EDX) spectrometer, atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements. Then, rGO–ZrP was employed as the adsorbent and the adsorption characteristics of rGO–ZrP toward methylene blue (MB) were evaluated under laboratory conditions. The results showed that rGO–ZrP possessed a higher BET specific surface area relative to rGO. The maximum adsorption quantity of MB onto the new prepared rGO–ZrP was ∼1.38 g/g at 30 °C. With the increase of storage day, the BET specific surface area and the maximum adsorption capacity of rGO–ZrP approximately remained unchanged. Under the maximum adsorption capacity, the adsorption quantity of MB onto rGO–ZrP was dependent on the initial concentration of MB, and higher temperature could facilitate the adsorption process. The efficiency of rGO–ZrP almost remained constant during the first six cycles of adsorption–desorption process. In addition, the fluorescence spectra implied that the adsorption of MB onto rGO–ZrP was a π–π stacking adsorption process, and the pillared structure of rGO–ZrP greatly enhanced the noncovalent adhesion. In conclusion, rGO–ZrP could serve as a promising adsorbent for the removal of MB in waste water.

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