Elemental mercury (Hg) removal from coal syngas using magnetic tea-biochar: Experimental and theoretical insights.

Mercury is ranked 3 as a global pollutant because of its long persistence in the environment. Approximately 65% of its anthropogenic emission (Hg) to the atmosphere is from coal-thermal power plants. Thus, the Hg emission control from coal-thermal power plants is inevitable. Therefore, multiple sorbent materials were synthesized using a one-step pyrolysis method to capture the Hg from simulated coal syngas. Results showed, the Hg removal performance of the sorbents increased by the citric acid/ultrasonic application. T5CUF demonstrated the highest Hg 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% H, 10 ppmV HCl, 6% HO, and 400 ppmV HS). The Hg removal mechanism was proposed, revealing that the chemisorption governs the Hg removal process. Besides, the active Hg removal performance is attributed to the high dispersion of valence FeO and lattice oxygen (α) contents over the T5CUF surface. In addition, the temperature programmed desorption (TPD) and XPS analysis confirmed that HS/HCl gases generate active sites over the sorbent surface, facilitating high Hg adsorption from syngas. This work represented a facile and practical pathway for utilizing cheap and eco-friendly tea waste to control the Hg emission.