羟基氧化铁/膨胀石墨复合材料的制备及除砷机制

以膨胀石墨为载体材料，采用改进后的综合法制备的羟基氧化铁（FeOOH）为改性材料，在酸性及超声波振荡的条件下对膨胀石墨进行表面接枝，制得羟基氧化铁/膨胀石墨复合材料，并对材料进行扫描电子显微镜（SEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）和X射线光电子能谱（XPS）表征，随后测试了其除砷性能，并探讨了反应机理.实验结果表明，复合材料中羟基氧化铁通过氢键与化学键均匀负载在了膨胀石墨表面，为亚微米级球状；使用0.5 g复合材料处理50 mL浓度为0.5 mg/L的模拟含砷废水，90 min后去除率可达到99%，且经过处理可以使废水中的砷浓度达到饮用标准；载铁量越高，材料的除砷性能越好，当载铁量达到55%时，使用0.5 g复合材料处理50 mL浓度为2.0 mg/L的模拟含砷废水，1 h后去除率达到72.6%，是普通膨胀石墨的3倍；该除砷过程由解离的羟基氧化铁与砷在复合材料附近完成，符合二级动力学方程和Temkin等温吸附模型.

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.