Novel magnetic biochars (MBC) were prepared by one-step pyrolysis of FeCl-laden biomass and employed for Hg removal in simulated combustion flue gas. The sample characterization indicated that highly dispersed FeO particles could be deposited on the MBC surface. Both enhanced surface area and excellent magnetization property were obtained. With the activation of FeCl, more oxygen-rich functional groups were formed on the MBC, especially the C═O group. The MBC exhibited far greater Hg removal performance compared to the nonmagnetic biochar (NMBC) under N + 4% O atmosphere in a wide reaction temperature window (120-250 °C). The optimal pyrolysis temperature for the preparation of MBC is 600 °C, and the best FeCl/biomass impregnation mass ratio is 1.5 g/g. At the optimal temperature (120 °C), the FeMBC was superior in both Hg adsorption capacity and adsorption rate to a commercial brominated activated carbon (Br-AC) used for mercury removal in power plants. The mechanism of Hg removal was proposed, and there are two types of active adsorption/oxidation sites for Hg: FeO and oxygen-rich functional groups. The role of FeO in Hg removal was attributed to the Fe(t) coordination and lattice oxygen. The C═O group could act as act as electron acceptors, facilitating the electron transfer for Hg oxidation.

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TiO 2 catalyst in an internal-illuminated honeycomb photoreactor was prepared for Hg 0 removal from flue gas. The Hg 0 removal efficiency was above 95% under the optimal operation condition. With the increasing TiO 2 coating value, the Hg 0 removal efficiency significantly increased. The catalyst calcined at 400 °C presented optimal Hg 0 removal performance, while higher calcination temperature weakened the Hg 0 photocatalytic removal activity. Similar Hg 0 removal performances were obtained under UV irradiation when the reaction temperature was in the range 25−90 °C, and 1.5 mW/cm 2 of UV light irradiation was competent for Hg 0 photocatalytic removal. With the same quantity utilization of TiO 2 catalyst, the internal-illuminated honeycomb photoreactor presented better Hg 0 removal performance than the fixed-bed reactor. Finally, the procedure of Hg removal from flue gas over TiO 2 catalyst in internal-illuminated honeycomb photoreactor was proposed, and the product in the Hg 0 photocatalytic removal process was analyzed as well.

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