Rice husk , as an abundant agricultural waste and renewable biomass, is adopted to produce porous silica which is used as a potential carbon-free adsorbent for mercury emission control of coal-fired power plants. The rice husk derived porous silica (RHS) exhibits a good Hg 0 adsorption capability with Hg 0 removal efficiency above 80% in the temperature range of 60–140 °C, which is plausibly due to the big specific surface area and mesoporous structure. The mercury removal performance of RHS can be evidently reinforced by KBr modification. The optimal KBr loading value and reaction temperature are 2 wt% and 140 °C, respectively. Acidic gas components, such as NO and SO 2 , both show slight inhibitive effects on Hg 0 adsorption process probably owing to the competitive adsorption or the elimination of adsorption sites.
Gaseous Hg 0 is one of the most deadly and hard-to-dispose pollutants. The oxidation of Hg 0 is a promising route, but the rational design and synthesis of highly efficient catalysts still remain grand challenges. Herein, CuO@Cu 2 O (or Cu x O) heterostructured nanoparticles uniformly monodispersing on porous carbon monolith were designed and successfully synthesized using oligo( m -phenylenediamine)-Cu 2+ complex as raw material. The Cu x O-carbon catalyst contains ∼28 wt% of Cu. Based on density functional theory calculation, the CuO@Cu 2 O junction interfaces can accelerate the Hg 0 oxidation by significantly reducing the energy barriers of reaction. Only 1 mg of the catalyst can catalyze the oxidation of more than 90 % of Hg 0 with [HCl] = 0.5 ppm, [O 2 ] = 6 vol%, T = 150 °C. The poisoning effect of either SO 2 or H 2 O on the catalysts is weak. Moreover, a long-term test confirmed that the Hg 0 oxidation rate can maintain more than 90 % even in the co-presence of SO 2 (5000 ppm) and H 2 O (10 vol%).