Strengthen the Affinity of Element Mercury on the Carbon-Based Material by Adjusting the Coordination Environment of Single-Site Manganese

Abstract

Mercury, as a highly poisonous pollutant, poses a severe threat to the global population. However, the removal of Hg 0 can only be carried out at below 100 °C due to the weak binding of the adsorbent. Herein, a series of carbon-based materials with different coordination environments and atomic dispersion of single-site manganese were prepared, and their elemental mercury removal performance was systematically investigated. It was demonstrated that the coordination environment around manganese determines its electronic structure and size, thus affecting its affinity with mercury. The obtained best adsorbents atomically dispersed Mn with atom size near 0.2 nm, achieves high Hg 0 removal efficiency and over 13 mg/g Hg 0 adsorption capacity at 200 °C. And the SO 2 resistance performance of single atoms (∼0.2 nm) is much better than clusters (∼1− 2 nm) because of its high selectivity, that the effect of SO 2 is only 3%. Density functional theory (DFT) reveals that Mn with four-nitrogen atoms (Mn−N 4 -CO) is more active than other number nitrogen coordination materials. Moreover, the presence of carboxyl groups around manganese also promotes affinity for Hg 0 . This work might shed new light on the enhancement of Hg 0 affinity in carbon-based materials and the rational design of the coordination structure of the tunable Hg 0 activities.

Regulated adsorption sites using atomically single cluster over biochar for efficient elemental mercury uptake

“…The efficiencies of the best-performing samples Mn δ -N 2 O 2 /BC shrimp (600) and Mn δ -N 2 O 2 /BC shrimp (700) reached 99.5% and 99.7% at 50 min, respectively. The mercury removal performance of Mn δ -N 2 O 2 /BC shrimp decreased when the pyrolysis temperature reached 900 °C, which is consistent with our previous research revealing that a high pyrolysis temperature exerted a negative effect on the affinity of the active components for Hg 0 (Li et al 2021). However, the Hg 0 -TPD results (Fig.…”

“…The adsorption capacity of Hg 0 within 300 min was significantly improved, up to 11.27 mg/g in Mn δ -N 2 O 2 /BC shrimp , verifying the universality of this method. Regardless of whether it is a conventional commercial activated carbon or manganese oxide adsorbent, its adsorption capacity for Hg 0 is generally limited under the same conditions (Li et al 2021;Ye et al 2021). Compared with other biomass-based Hg 0 removal materials, the adsorption capacity was improved by several orders of magnitude (Table 1).…”

Tunable Redox Cycle and Enhanced π-Complexation in Acetylene Hydrochlorination over RuCu Catalysts

“…For RuCu(II)/AC, RuCu(I)/AC, and RuCu(0)/AC catalysts, weight loss accompanied by an exothermic peak appeared in the range of ∼100−300 °C, corresponding to the decomposition of certain compounds on the catalysts. 44 The continuous weight loss of the catalysts once the temperature exceeds ∼500 °C is attributed to the combustion of the AC support itself. Thus, coke combustion may occur at ∼300−475 °C.…”

Spontaneous adsorption–oxidation of gaseous elemental mercury via a conjugated unit –NH+˙–Cl*: creation and mechanisms

“…5,6 However, ACI technology suffers from high operating costs and a narrow applicable temperature range. 7,8 Consequently, many researchers have developed various S-, Zn-, Fe-, or Mn-based adsorbents to remove gaseous Hg 0 , including nano-ZnS, 9,10 Na 2 S and S 0 /PACs, 11 nano-sulfides, 3 γ-Fe 2 O 3 , 12,13 Fe 1.5 MBC 600 , 14 Fe 3− x Mn x O 4 /CNF, 15 LaMnO 3 , 16,17 MnO x /graphene, 18 and single-site manganese, 19 and reported good performance for Hg 0 removal. However, the regeneration process of these sorbents needs high temperature and the performance of the regenerated sorbents is not so good, which makes them not suitable for continuous reuse and so they finally turn into hazardous waste, resulting in a high secondary disposal cost.…”