Removal of elemental mercury using large surface area micro-porous corn cob activated carbon by zinc chloride activation

Abstract

It is a big challenge to effectively remove elemental mercury (Hg0) from coal fired flue gas with affordable adsorbents. To explore new adsorbents with low cost and high capacity for mercury removal is urgently demanded. On the other hand, it will be a good way to reduce the environmental burden by beneficially utilizing agricultural waste. In this study, one kind of agricultural waste, corn cob, was beneficially used for Hg0 control. The corn cob activated carbon (CCAC) with large surface area was prepared by chemical activation using ZnCl2 and was employed to remove elemental mercury (Hg0) from simulated flue gas (SFG) for the first time. The results demonstrated that the corn cob activated carbon performed high mercury removal efficiency up to 91.4% at 150 °C. The effects of activator, reaction temperature and main flue gas components were studied. Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive X-ray spectrometry (SEM-EDX) were used to characterize the physicochemical properties of the adsorbents. The possible mechanism of mercury removal was discussed based on XPS analysis and characterization. The results indicated that ZnCl2 could not only activate microporous structures of carbon but also played an important role for removal of elemental mercury. The produced AC can be used as an effective adsorbent with low cost for mercury pollution control in flue gas.