Regulated adsorption sites using atomically single cluster over biochar for efficient elemental mercury uptake
Jiaxing Li, Hongli Li, Haomiao Xu, Qinyuan Hong, Leipeng Ji, Zhisong Liu, Yixiang Qiu, Wenjun Huang, Naiqiang Yan, Zan Qu
Abstract
Abstract Carbon-based materials have been widely used in gaseous pollutant removal because of their sufficient surface functional groups; however, its removal efficiency for elemental mercury (Hg 0 ) is low. In this study, we fabricated biomass using a chelated coupled pyrolysis strategy and further constructed the regulated adsorption sites for gaseous Hg 0 uptake. A series of Mn δ -N 2 O 2 /BC with different manganese cluster sizes demonstrated that manganese clusters anchored on biochar acted as highly active and durable adsorbents for Hg 0 immobilization, which increased the adsorption efficiency of Hg 0 by up to 50%. Shrimp- and crab-based biochar adsorbents exhibited excellent Hg 0 removal because of their chitosan-like structure. In particular, small Mn clusters and oxygen species around the defect led to a boost in the Hg 0 adsorption by carbon. The results of density functional theory calculation revealed that the presence of oxygen in the carbon skeleton can tune the electrons of small-sized Mn clusters, thereby promoting the affinity of mercury atoms. The newly developed Mn δ -N 2 O 2 /BC shrimp had an adsorption capacity of 7.98–11.52 mg g −1 over a broad temperature range (50–200 °C) and showed a high tolerance to different industrial flue gases (H 2 O, NO, HCl, and SO 2 ). These results provide novel green and low-carbon disposal methods for biomass resource utilization and industrial Hg 0 emission control. Graphical Abstract