One-step preparation of functionalized cotton exocarp-based sorbent for efficient Hg0 immobilization

Activated carbon (AC) injection has been regarded as one of the most effective control technologies for Hg0 removal in flue gas. It is worthwhile to explore new and simple preparation methods for AC with low cost and high Hg removal capacity. In this study, a biomass based AC was successfully prepared from levant cotton exocarp using ZnCl2 activation. The mercury adsorption efficiency and mechanism were studied via the fixed bed experiments. Activator, reaction temperature and components of simulated coal-fired flue gas were investigated. Brunauer–Emmett–Teller (BET), scanning electron microscopy with energy-dispersive X-ray spectrometry (SEM–EDX) and X-ray photoelectron spectroscopy (XPS) were applied for morphology characterization of the prepared AC and discussion of the possible adsorption mechanism. The adsorbed mercury species and the physiochemical properties of prepared AC were discussed. The results showed that (1) Hg0 removal efficiency could reach up to 90% at 150 ℃ under simulated flue gas (SFG); (2) Hg0 adsorption was controlled by the combination of physical and chemical mechanisms.