impact of divalent cations on fouling potential of bicarbonate-form anion exchange resins
TRANSCRIPT
PRELIMINARY DATA
MOTIVATIONS
Increased water demands & diminishing high quality water sources lead to the use of previously underutilized technologies
METHODOLOGY
CONCLUSIONS
• The presence of calcium in solution negatively
impacts the performance of ion exchange for both
bicarbonate-form and chloride-form. The presence
of magnesium also impacts performance.
• Chloride-form ion exchange isn’t impacted as
greatly by the presence of divalent cations as
bicarbonate-form.
• Bicarbonate-form anion exchange is greatly
impacted by the presence of divalent cations. The
presence of magnesium has the most profound and
immediate impact.
FUTURE WORK
• Complete additional regeneration cycles and
perform regeneration cycles on waters containing
no cations, and waters containing Co2+.
• Investigate the biological fouling of bicarbonate-
form biological fouling
• Innovative regeneration by CO2(g) sparging and
optimization
Figure 1: Preliminary results showing resin performance in
absence of divalent cations. Synthetic water contained Santa
Fe River NOM, nitrate, sulfate, bicarbonate, and chloride.
Figure adapted from Rokicki and Boyer 20112.
Calcium
Magnesium
Figure 3: DOC removal by chloride-form ion exchange resins over
multiple regeneration cycles in the presence of calcium. Figure 4: DOC removal by bicarbonate-form ion exchange resins over
multiple regeneration cycles in the presence of calcium.
Species pKsp1
MgCO3 5.17
CaCO3 8.54
CoCO3 12.84
Species mg/L meq/L
Cl- 4.03 0.06895
HCO3- 5.79 0.06895
SRNOM 14 0.06895
X2+ Varies 0.06895
Figure 5: DOC removal by chloride-form ion exchange resins over
multiple regeneration cycles in the presence of magnesium.
Figure 6: DOC removal by bicarbonate-form ion exchange resins over
multiple regeneration cycles in the presence of magnesium.
• Jar tests are run in
triplicate
• Regeneration occurs
at 100x equivalence
capacity of resin
ACKNOWLEDGEMENTS
The author would like to thank Dr. Treavor Boyer for all
his support and guidance. I would also like to thank
the Boyer research team for all their help and support
in and out of the laboratory.
References 1Dean, J.A., 1999. Lange's Handbook of Chemistry, 15th ed.
McGraw-Hill.. 2Rokicki, C.A., Boyer, T.H., 2011. Bicarbonate-form anion
exchange: Affinity, regeneration, and stoichiometry.
Water Research 45, 1329 -1337. 3Walker K.M., Boyer, T.H., 2011. Long-term performance of
bicarbonate-form anion exchange: Removal of dissolved
organic matter and bromide from the St. Johns River,
FL, USA.. Water Research 45 (9), 2875-2886.
RESULTS
• Ion exchange (IEX) may be a treatment
solution for certain waters with higher
levels of natural organic matter (NOM):
IEX ResinNOM
NOM
NOM
NOM
HCO3-
HCO3-
HCO3-
HCO3-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
IEX Resin
NOM
NOMNOM
NOM
HCO3-
HCO3-
HCO3-HCO3
-
Cl-
Cl-Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
Cl-
• However, brine associated with chloride-
form resin limits the potential applications
of IEX. Bicarbonate-form would generate
easier to dispose of regenerant and would
prevent increase of salinity of local waters.
• It is unknown how the presence of
bicarbonate within the resin structure will
react with divalent cations:
Table 2: Synthetic water
composition
Table 1: Carbonate mineral
solubility products. Table adapted
from Dean 19991
Kinetic study jar tests:
Regeneration of resin:
IEX Resin
HCO3-
HCO3-
X2+
X2+
H+
H+HCO3-
Brine disposal is a major concern,
much like RO concentrate, it often
impedes the implementation of this
technology.
Impact of divalent cations on fouling potential of
bicarbonate-form anion exchange resins Christopher A. Rokicki, and Treavor H. Boyer1
Department of Environmental Engineering Sciences, University of Florida, Gainesville, FL [email protected] ~ (352)846-3351 ~ http://www.ees.ufl.edu/homepp/boyer/
Figure 2: SEM images of chloride- and bicarbonate-form
resin after 14 regenerations. Figure adapted from Walker
and Boyer 20113.
0.5ml/LIEX resin
1L DI& salt
Mix 30min at 150 RPM
Stop, allow to settle, decant
Add 1L DI to wash, mix 10min
Repeat twice
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
r0 r1 r2 r3
% D
OC
re
mo
va
l
regeneration#
M-Cl
M-HCO3
0%
10%
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0 50 100
% D
OC
rem
oval
time (min)
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r3
chloride-form chloride-form
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0 50 100
% D
OC
rem
oval
time (min)
r0
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bicarbonate-form
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0 50 100
% D
OC
rem
oval
time (min)
r0
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bicarbonate-form
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0 50 100
% D
OC
rem
oval
time (min)
r0
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chloride-form