Elemental mercury (Hg0) removal from coal syngas using magnetic tea-biochar: Experimental and theoretical insights
Fazeel Abid , Adnan Raza Altaf , Yusuf G. Adewuyi , Haipeng Teng , Gang Liu
DOI:10.1016/j.jes.2021.09.033
Received July 15, 2021,Revised , Accepted September 26, 2021, Available online February 02, 2022
Volume 122,2022,Pages 150-161
Mercury is ranked 3rd as a global pollutant because of its long persistence in the environment. Approximately 65% of its anthropogenic emission (Hg0) to the atmosphere is from coal-thermal power plants. Thus, the Hg0 emission control from coal-thermal power plants is inevitable. Therefore, multiple sorbent materials were synthesized using a one-step pyrolysis method to capture the Hg0 from simulated coal syngas. Results showed, the Hg0 removal performance of the sorbents increased by the citric acid/ultrasonic application. T5CUF0.3 demonstrated the highest Hg0 capturing performance with an adsorption capacity of 106.81 µg/g within 60 min at 200 °C under complex simulated syngas mixture (20% CO, 20% H2, 10 ppmV HCl, 6% H2O, and 400 ppmV H2S). The Hg0 removal mechanism was proposed, revealing that the chemisorption governs the Hg0 removal process. Besides, the active Hg0 removal performance is attributed to the high dispersion of valence Fe3O4 and lattice oxygen (α) contents over the T5CUF0.3 surface. In addition, the temperature programmed desorption (TPD) and XPS analysis confirmed that H2S/HCl gases generate active sites over the sorbent surface, facilitating high Hg0 adsorption from syngas. This work represented a facile and practical pathway for utilizing cheap and eco-friendly tea waste to control the Hg0 emission.
