A novel magnesium ascorbyl phosphate graphene-based monolith and its superior adsorption capability for bisphenol A

In this study, a non-shell graphene-based monolith (GBM) with huge surface area was synthesized by chemical reduction of Graphene oxide (GO) using magnesium ascorbyl phosphate (MAP), and tested as an adsorbent for trace Bisphenol A (BPA) removal. The properties of MAP-GBM was characterized by scanning electron microscopy (SEM), Brunauer-Emmett-Teller N-2 specific surface area (BET), X-ray powder diffraction, Fourier transform-infrared (FTIR), Raman, and X-ray photoelectron spectroscopies. BPA adsorption was investigated in batch and column adsorption experiments. The data showed that MAP-GBM was a three-dimensional (3D) graphene material with macrostructure and most C=C double bonds were recovered. Adsorption isotherms and kinetics of BPA on MAP-GBM followed the Langmuir model and fitted well with a pseudo-second-order kinetic model, respectively, and the adsorption process was endothermic. The saturated adsorption capacity of MAP-GBM was 324 mg/g for BPA, which was 2.43 times of that of ascorbic acid-GBM. A MAP-GBM adsorption column completely removed BPA from solution at low concentration (50 mu g/L) for similar to 450 mL. This efficiency is much higher than traditional adsorbents such as activated carbon, which could be ascribed to the unique 3D porous structure, hydrogen bonding, and pi-pi interaction characteristics of this MAP-GBM. The material can be easily regenerated by simply immersing in methanol for 24 h, and the adsorption efficiency remain as high as 88% after five regenerations. These findings demonstrated that MAP-GBM is a promising adsorbent for the effective and cost-efficient removal of low concentration endocrine-disrupting chemicals.