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  • Evaluation of cation exchange membrane performance under exposure to high Hg<sup>0</sup> and HgBr<sub>2</sub> concentrations
Title: Evaluation of cation exchange membrane performance under exposure to high Hg<sup>0</sup> and HgBr<sub>2</sub> concentrations
Abstract. Reactive mercury (RM), the sum of both gaseous oxidized Hg and particulatebound Hg, is an important component of the global atmospheric mercury cycle,but measurement currently depends on uncalibrated operationally definedmethods with large uncertainty and demonstrated interferences and artifacts.Cation exchange membranes (CEMs) provide a promising alternative methodologyfor quantification of RM, but method validation and improvements are ongoing.For the CEM material to be reliable, uptake of gaseous elemental mercury(GEM) must be negligible under all conditions and RM compounds must becaptured and retained with high efficiency. In this study, the performance ofCEM material under exposure to high concentrations of GEM (1.43×106 to 1.85×106 pg m−3) and reactive gaseous mercurybromide (HgBr2 ∼5000 pg m−3) was explored using acustom-built mercury vapor permeation system. Quantification of totalpermeated Hg was measured via pyrolysis at 600 ∘C and detectionusing a Tekran® 2537A. Permeation tests wereconducted over 24 to 72 h in clean laboratory air, with absolute humiditylevels ranging from 0.1 to 10 g m−3 water vapor. GEM uptake by the CEMmaterial averaged no more than 0.004 % of total exposure for all testconditions, which equates to a non-detectable GEM artifact for typicalambient air sample concentrations. Recovery of HgBr2 on CEM filters wason average 127 % compared to calculated total permeated HgBr2 based onthe downstream Tekran® 2537A data. The lowHgBr2 breakthrough on the downstream CEMs (< 1 %) suggests thatthe elevated recoveries are more likely related to suboptimal pyrolyzerconditions or inefficient collection on the Tekran® 2537A gold traps.  more » « less
Award ID(s):
1700711
NSF-PAR ID:
10216376
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Atmospheric Measurement Techniques
Volume:
12
Issue:
2
ISSN:
1867-8548
Page Range / eLocation ID:
1207 to 1217
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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