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