The fly ash from a coal-fired power plants was modified with non-thermal plasma in air to improve the elemental mercury (Hg0) removal performance. The Hg0 adsorption experiments were implemented via a bench-scale fixed-bed reactor system. Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), ultimate, X-ray diffraction (XRD) and XRF analysis were employed to characterize the fly ash. The effect of non-thermal plasma voltage and time on Hg0 removal efficiency was investigated. The results showed that fly ash had better Hg0 removal performance when treatment voltage was 3.0 kV and treatment time was 7 min. Furthermore, the results showed that non-thermal plasma treatment had little influence on the specific surface area. However, non-thermal plasma treatment increased the relative content of oxygen. XPS and temperature programmed desorption results indicated that Hg0 removal process included adsorption and oxidation of Hg0. Moreover, ester and carbonyl groups played extremely vital roles in the improvement of Hg0 removal performance, and their temperature programmed desorption peak occurred at around 250°C and 320°C, respectively.
Keywords: Hg0 removal efficiency; Non-thermal plasma; ester and carbonyl groups; fly ash; temperature programmed desorption.