3D composite carbon Foam-Loaded MnO2 and FeOOH enabling the "oxidation-adsorption" effect toward efficient removal of arsenic from groundwater

The remediation of geogenic high arsenic groundwater is of great significance for environmental protection. In this study, a feasible strategy for in-situ growth of MnO2 and FeOOH on a three-dimensional (3D) porous carbon foam skeleton was developed by simple calcination carbonization and activation treatment of modified carbon foams. This work demonstrates that arsenic in aqueous solution can be efficiently removed by the dual function of "oxidation and adsorption" from the composite of MnO2-FeOOH co-loaded carbon foam (CF). The prepared 3D monolithic has the advantages of low cost, easy preparation, and independent integrity. It can be innovatively used for arsenic remediation of groundwater systems. The MnO2 serves as the oxidizer to convert highly toxic As (III) into less toxic As(V), the FeOOH acts as the adsorbent for the capture of As(V), and CF offers an interconnected porous network for efficient mass transfer as well as a robust skeleton for facile recycling. The maximum adsorption capacity of As(III) and As(V) for MnO2-FeOOH@CF can reach 63 and 78 mg g-1, respectively. After repeatedly utilizing the free-standing adsorbent three times, its adsorption capacity for As(III) and As(V) can still reach 84 % and 85 % of the initial adsorption capacity, respectively. The low cost, high efficiency of arsenic removal, and easy preparation and recycling endow the MnO2-FeOOH@CF to be a promising adsorbent in practical application.