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

Abstract

Removing gaseous elemental mercury (Hg0) from Hg-involved tail gas is a hot topic but also a great challenge. Herein, we developed a novel cost-effective and ultralight material, Cl-doped protonated polyaniline...

Multimedia Mercury Recovery from Coal-Fired Power Plants Utilizing N-Containing Conjugated Polymer Functionalized Fly Ash

“…The N 1s XPS spectra (Figure k) in P1-HCl/FA4 and P2-HCl/FA4 can be deconvoluted into four peaks centered at 398.5 (398.6), 399.2 (399.6), 400.1 (400.5), and 401.6 (401.7) eV, corresponding to quinoid imine (N−), benzoic amine (−NH−), positively charged imine (≈NH + –, including −NH + • – and NH + −), and amine (−NH 2 + −), respectively. ,, The Cl 2p spectra of P1-HCl/FA4 and P2-HCl/FA4 in Figure l can be deconvoluted into four peaks at 197.1 (197.4), 198.5 (199.0), 198.7 (199.0), and 200.1 (200.6) eV, which are attributed to Cl – 2p 3/2 , Cl* 2p 3/2 , Cl – 2p 1/2 , and Cl* 2p 1/2 , respectively, indicating the presence of free Cl – and the active covalent Cl*. , Besides, the Cl 2p spectrum of HCl/FA also demonstrates the formation of covalent Cl (200.2 eV) but not the active covalent Cl*, so its activity is far lower than that combined with N sites. The formation of PANI and PPy and the presence of −NH + • – and active Cl* confirm the creation of the mercury affinity unit −NH + • –Cl*. ,, …”

“…The formation of PANI and PPy and the presence of −NH + • − and active Cl* confirm the creation of the mercury affinity unit −NH + • −Cl*. 1,2,39 3.2. Multistate Hg Removal Performance Evaluation.…”

“…In Figure d, the Hg 0 removal efficiency of P2-HCl/FA4 is not affected by the presence of NO but slightly decreases by about 5–8% when SO 2 is added and linearly decreases to 55.5% when the O 2 content increases to 15%. The inhibition caused by O 2 was due to the excessive oxidation of polymer, which resulted in the decrease in activity Figure e provides the Hg 0 dynamic adsorption capacity of different samples: compared with FA4 (0 μg/g, 97.8%) and HCl/FA4 (7.11 μg/g, 80%), the Hg 0 adsorption capacity for P1-HCl/FA4 achieves 756.24 μg/g (50% penetration, 106-fold of HCl/FA4) and that for P2-HCl/FA4 reaches 116.20 μg/g (70% penetration, 16-fold of HCl/FA4), respectively.…”

“…Based on our previous works, 1,39 the −NH + • −Cl* functional unit contributes the most to Hg 0 removal: Hg 0 is initially adsorbed by −NH + • − and then bonds with Cl* to form HgCl X �PANI/PPy. To further understand the property of −NH + • −Cl* and figure out the inactivation reasons for P1-HCl/FA4 and P2-HCl/FA4 under high temperature (Figure S7), the following experiments and characterizations were conducted: P1-HCl/FA4 and P2-HCl/FA4 were heated for 6 h at 140 °C in a N 2 atmosphere, marked as TP1-HCl/FA4 and TP2-HCl/FA4.…”

“…The inhibition caused by O 2 was due to the excessive oxidation of polymer, which resulted in the decrease in activity. 39 Figure 2e provides the Hg 0 dynamic adsorption capacity of different samples: compared with FA4 (0 μg/g, 97.8%) and HCl/FA4 (7.11 μg/g, 80%), the Hg 0 adsorption capacity for P1-HCl/FA4 achieves 756.24 μg/g (50% penetration, 106-fold of HCl/FA4) and that for P2-HCl/ FA4 reaches 116.20 μg/g (70% penetration, 16-fold of HCl/ FA4), respectively. Then, the Elovich model (eq 3), fitting well with experimental data (correlation coefficient R 2 are 0.9999, 0.9998, and 0.9997, respectively), was used to obtain the equilibrium adsorption capacities of these samples: 20.38 μg/g (HCl/FA4), 1623.16 μg/g (P1-HCl/FA4), 246.50 μg/g (P2-HCl/FA4), respectively (Figures 2f and S8).…”