Due to the restrictions on mercury
mining, recovering the mercury
from mercury-containing waste is attracting increasing attention.
This study successfully achieved the removal and recovery of gaseous
elemental mercury (Hg0) by using membrane technology. A
novel composite membrane of Cl-doped protonated polypyrrole-coated
multiwall carbon nanotubes (Cl-PPy@MWCNTs) was fabricated in which
MWCNTs acted as the framework to support the active component Cl-PPy.
The morphology, structure, and composition of the prepared membranes
were determined by field emission scanning electron microcopy, energy-dispersive
spectroscopy, X-ray photoelectron spectroscopy, Fourier-transform
infrared spectroscopy, etc. The composite membrane exhibited an excellent
performance in Hg0 removal (97.3%) at a high space velocity
of 200,000 h–1. The dynamical adsorption capacity
of Hg0 was 3.87 mg/g when the Hg0 breakthrough
reached 10%. The adsorbed Hg0 could be recovered/enriched
via a leaching process using acidic NaCl solution; meanwhile, the
membrane was regenerated. The recovered mercury was identified in
the form of Hg2+, with a recovery efficiency of over 99%.
Density functional theory calculations and mechanism analysis clarified
that the electrons of Hg0 transported to the delocalized
electron orbits of protonated PPy and then combined with Cl– to form Hg2Cl2/HgCl2. Finally,
we first demonstrated that the analogous protonated conductive polymers
(e.g., polyaniline) also possessed good Hg0 removal ability,
implying that such species may offer more outstanding answers and
attract attention in future.
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...
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