Removal of mercury and methylene blue from aqueous solution by xanthate functionalized magnetic graphene oxide: Sorption kinetic and uptake mechanism

• Fe3O4-xGO was synthesized by linking xanthate groups to magnetic graphene (Fe3O4-GS).
• Fe3O4-xGO was an ideal adsorbent to adsorb Hg(II) and MB with high efficiency.
• Adsorption was well interpreted by Langmuir and pseudo-second order kinetic models.
• The adsorption process was endothermic and spontaneous in nature.

Xanthate functionalized magnetic graphene oxide (Fe3O4-xGO) was successfully synthesized through linking xanthate groups to a kind of graphenes magnetic material (Fe3O4-GS). Fe3O4-xGO was found to be an ideal adsorbent for Hg(II) and methylene blue removal with a higher adsorption capacity. The synthesized adsorbent was characterized by SEM, TEM, FTIR, XRD, and BET respectively. Fe3O4-xGO can be simply recovered from water with magnetic separation at low magnetic field within only 1 min. The adsorption capacity was found to be 118.55 mg g−1 for Hg2+ (contact time for 180 min, pH at 7 and temperature at 25 °C) and 526.32 mg g−1 for methylene blue (contact time for 120 min, pH at 5.5 and temperature at 25 °C), respectively. Kinetic data showed good correlation with pseudo-second-order equation and the Langmuir model was found to fit for the isotherm data, which showed the contaminant sorption was accomplished mainly via chelation or ion exchange. The results of thermodynamic studies (ΔG < 0, ΔH > 0, ΔS > 0) illustrate that the adsorption process was endothermic and spontaneous in nature. The experimental results suggest that Fe3O4-xGO has the potential applications in the environmental management.

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