Preparation and Arsenic Removal Mechanism of Iron Oxyhydroxide/expanded Graphite Composite Material

Iron oxyhydroxide/expanded graphite composites were prepared via surface grafting under the environment of acid and ultrasonic oscillations, with expanded graphite as carrier material and iron oxyhydroxide (FeOOH) prepared as the modifier. Scanning electronic microscopy (SEM), X-ray diffraction (XRD) X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) techniques were employed to characterize the composite. Then the removal performance of arsenic by the composite was determined. The results show that the iron oxyhydroxide loaded on the surface of expanded graphite evenly as the sub-micron spherical by hydrogen bond and chemical bonds. The removal rate of arsenic can reach 99% using 0.5 g composite to treat 50 mL simulated waste water containing 0.5 mg/L arsenic after 90 min, and the treated waste water can reach the drinking standard. The removal rate of arsenic by the composite improves with the increase of iron content in the composite, and when the iron content in the composite reaches 55%, the removal rate of arsenic can reach 72. 6% using 0.5 g composite to treat 50 mL simulated waste water containing 2. 0 mg/L arsenic within 60 min, three times as high as that of ordinary expanded graphite. In addition, the dissociated iron oxyhydroxide reacts with arsenic in the vicinity of the composite material and the removal process of arsenic confirms to the secondary dynamics equation and Temkin isotherm adsorption model.