Adsorption behaviors and mechanism of graphene oxide for silver complex anion removal

Graphene oxide (GO) is an outstanding material for water treatment, their film structure and functional groups may play crucial roles in anion removal. Herein, the removal of silver complex anion Ag(CN)(2)(-) by GO was conducted to study the behavior and mechanism of GO in silver exceeded system. The work was carried out by the adsorption of Ag(CN)(2)(-) on GO as functions of pH, adsorption time and adsorbate concentration. The results, based on XRD, SEM, TEM, AFM, XPS, FT-IR, presented that the prepared GO has a film structure and amount of oxygenous functional groups. Further studies found that GO exhibits big adsorption capacity (100.7 mg/g) and high adsorption rate (0.0084 min(-1)) in accordance with the adsorption kinetics and isotherm, implying the GO might be a good potential adsorbent for Ag(CN)(2)(-) removal. The adsorption progress was found fits well with second-order adsorption model meanwhile follows Langmuir adsorption model well. The silver was confirmed adsorbed in form of Ag(CN)(2)(-) and distributed uniformly on GO. The adsorption performance and mechanism was ascribed to the film structure and the interactions between Ag(CN)(2)(-) and oxygenous functional groups, and the DFT calculation implied the groups contribute for adsorption in order of epoxy > hydroxyl > carboxyl.