Surface modification of fly ash by non-thermal air plasma for elemental mercury removal from coal-fired flue gas
2021
Shi, Mengting | Luo, Guangqian | Zhu, Hailu | Zou, Renjie | Hu, Jingyuan | Xu, Yang | Yao, Hong
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.
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