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Simultaneous Adsorption/Reduction of Bromate by Nanoscale Zerovalent Iron Supported on Modified Activated Carbon

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journal contribution
posted on 04.09.2013, 00:00 by Xiuqiong Wu, Qi Yang, Dechao Xu, Yu Zhong, Kun Luo, Xiaoming Li, Hongbo Chen, Guangming Zeng
Nanoscale zerovalent iron (nZVI) was reported as an effective material for the removal of bromate. However, its reactivity may be weakened due to its aggregation. In this study, nZVI was dispersed onto modified activated carbon (pretreated by nitric acid or/and ammonia) by impregnating carbon in ferrous sulfate with NaBH4 as reducing agent. The nZVI supported on modified activated carbon (nZVI/MAC) was characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM). Good distribution of nZVI particles (about 50 nm) on the MAC was observed. The removal efficiencies of bromate by AC, nZVI, and nZVI/MAC were respectively evaluated. Experimental results indicated that nZVI/MAC showed the highest removal efficiency to bromate. In addition, the effects of initial bromate concentration (0.78–3.91 μmol/L) and pH (2.0–10.0) were investigated by batch experiments. Kinetic studies showed that the simultaneous adsorption and reduction of bromate by nZVI/MAC followed pseudo-first-order kinetics. Finally, bromine mass balance demonstrated that bromide was the only product for bromate reduction by nZVI/MAC, suggesting that bromate in aqueous solution was first adsorbed onto nZVI/MAC and subsequently reduced to innocuous bromide by nZVI.