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Selective Removal of Nitrosamines from a Model Amine Carbon-Capture Waterwash Using Low-Cost Activated-Carbon Sorbents
journal contribution
posted on 2017-08-09, 00:00 authored by Leland
R. Widger, Megan Combs, Amit R. Lohe, Cameron A. Lippert, Jesse G. Thompson, Kunlei LiuNitrosamines
generated in the amine solvent loop of postcombustion
carbon capture systems are potent carcinogens, and their emission
could pose a serious threat to the environment or human health. Nitrosamine
emission control strategies are critical for the success of amine-based
carbon capture as the technology approaches industrial-scale deployment.
Waterwash systems have been used to control volatile and aerosol emissions,
including nitrosamines, from carbon-capture plants, but it is still
necessary to remove or destroy nitrosamines in the circulating waterwash
to prevent their subsequent emission into the environment. In this
study, a cost-effective method for selectively removing nitrosamines
from the absorber waterwash effluent with activated-carbon sorbents
was developed to reduce the environmental impact associated with amine-based
carbon capture. The results show that the commercial activated-carbon
sorbents tested have a high capacity and selectivity for nitrosamines
over the parent solvent amines, with capacities up to 190 mg/g carbon,
under simulated amine waterwash conditions. To further reduce costs,
an aerobic thermal sorbent regeneration step was also examined due
to the low thermal stability of nitrosamines. To model the effect
of oxidation on the sorbent performance, thermal- and acid-oxidized
sorbents were also prepared from the commercial sorbents and analyzed.
The chemical and physical properties of nitrosamines, the parent amine,
and the influence of the physical properties of the carbon sorbents
on nitrosamine adsorption was examined. Key sorbent properties included
the sorbent hydrophilicity and hydrophobicity, surface pKa of the sorbent, and chemical structure of the parent
amine and nitrosamine.
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Low-Cost Activated-Carbon Sorbents Nitrosaminesparent amineModel Amine Carbon-Capture Waterwashnitrosaminesorbent regeneration stepactivated-carbon sorbentsamine waterwash conditionsKey sorbent propertiesabsorber waterwash effluentamine-based carbontechnology approaches industrial-scale deploymentNitrosamine emission control strategiessurface p K
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