1.  Process:
1. Cellulose denuder impregnated with 6% phosphoric acid
2. 8-hour ammonia gas collection efficiency test with a feed
concentration of 10 ppm and flow rate 2 L/min
3. Determine the downstream concentration by applying
OSHA’s Validation Guidelines for Air Sampling Methods
Utilizing Chromatographic Analysis
 Reagents:
 85% phosphoric acid
 Methanol
 98% sulfuric acid
 Standard solution of ammonium ion
EXPERIMENTAL CONDITION
RESULTS
DENUDER MATERIAL
Whatman grade 541 Whatman grade 40
EXPERIMENTAL SETUP
 Denuder preparation caution
A New Cellulose Denuder for Measuring Ammonia Gas: the Validation Test
INTRODUCTION
Cheng-Tung Liu1, Chih-Hsiang Chien1, Alex Theodore1, Chang-Yu Wu1*, Yu-Mei Hsu2, Brian Birky3
OBJECTIVES
RESULTS
CONCLUSIONS
REFERENCES
 The disadvantage of the traditional samplers, glass
Honeycomb denuder or glass annular denuder, are
expensive and fragile material
 Confirm the mass conservation in this sampling
procedure
 Develop an inexpensive denuder which can collect
95% 10 ppm ammonia for 8 hours
 Denuder performance
 Filter paper could be deteriorated by high temperature. Air purge
should be the better way for coating drying
 20 folds well-spread denuder experiment showed that cellulose
denuder can absorb 10ppm NH3 for 8 hours
 20 folds and 40 folds condense-pack denuder experiment
showed the same decline rate for 8-hour collection performance,
which indicates the assemble of denuders is the important factor
for absorption
 The blank denuder test showed the experiment data is
meaningful. The minimum meaningful weight is 801 ug. The
minimum sampling time is 54 minutes.
 Based on the mass balance of 20 folds well-spread experiment,
the output/input is 88%. The reason of the 12% losses could be
instrumental or operational error
1. X. Chen, D. Day, B. Schichtel, W. Malm, A.K. Matzoll, J. Mojica, C.E. McDade,
E.D. Hardison, D.L. Hardison, S. Walters, M.V. Water, J.L. Collett jr. Seasonal
ambient ammonia and ammonium concentrations in a pilot IMPROVE NHx
monitoring network in the western United States. Atmospheric Environment 91
(2014) 118-126
 Gases ammonia reacts rapidly with atmospherically-
formed sulfuric and nitric acids to contribute to
ambient levels of secondary particulate matter and,
thus, result to visibility reduction
www.gelifesciences.comGas Flow
Diffusion
Cellulose membrane
a) Filter paper
under 65 oC
for 24 hours
denuder mass balance
1Department of Environmental Engineering Sciences, Engineering School of Sustainable Infrastructure and Environment, University of Florida, Gainesville, FL, USA.
2Wood Buffalo Environmental Association, Alberta, Canada 3Florida Industrial and Phosphate Research Institute, FL, USA
BENEFITS
 Ergonomically designed sampler allows accurate
measurement of ammonia gas
 Design for ambient ammonia gas measurement
 Effective, inexpensive, lightweight, and easy-to-
assemble gas collector
ACKNOWLEDGEMENT
The researchers would like to thank the Florida Industrial and Phosphate
Research Institute for funding this project. We would also like to thank Dr.
Treavor Boyer for sharing the laboratory instruments
Cellulose denuder capacities for 10 ppm NH4
+
The quantitative filter paper
featuring high wet strength
and chemical resistance
• Ash content: <0.006%
• Particle retention: 22 um
• Air flow rate: 3.8 s/100ml/in2
The ashless filter paper with
low speed and high
retention
• Ash content: <0.007%
• Particle retention: 8 um
• Air flow rate: 19.3 s/100ml/in2
Accordion Shape Denuder
 Apparatus:
 Ion chromatography
 Mass flow controller
 Relative humidity meter
 Rotameter
 Experiment:
 20 folds denuder under low relative humidity
 40 folds denuder under low relative humidity
 Feed ammonia gas calibration test
Source: URG corporation
b) Filter paper
dried by air
purge
70%
75%
80%
85%
90%
95%
100%
105%
0 2 4 6 8 10
Collectionefficiency(%)
Time (hr)
 Calibration
• Method: Measured one hour feed ammonia
gas without denuder
• Results: Massoutput / Massinputx 100%= 89%
 Blank
• Signal/Noise=denuders/blank= 17.9
• Minimum meaningful weight of NH4
+ from
denuders is 801 ug (for S/N>=3, NH4
+ will be
>16.02 ppm)
• For S/N> 3, The minimum sampling time for
10 ppm ammonia gas with flow rate of 2 L/min
is 54 mins
Reaction equation:
 Directly measured the upstream and downstream concentration by IC
P = Ndown / Nup x 100%
Nup : upstream ammonium concentration.
Ndown : downstream ammonium concentration
10 ppm
NH3
2 L/min
20 folds
20 folds
40 folds
0
1000
2000
3000
4000
5000
6000
7000
8000
input 20 folds
well-spread
output 20 folds
well-spread
input 20 folds
condense
output 20 folds
condense
input 40 folds
condense
output 40 folds
condense
Ammonium(ug)
denuder
bubbler
calculated