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 1thboyer@ufl.edu ~ (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%

20%

30%

40%

50%

0 50 100

% D

OC

rem

oval

time (min)

r0

r1

r2

r3

chloride-form chloride-form

0%

10%

20%

30%

40%

50%

0 50 100

% D

OC

rem

oval

time (min)

r0

r1

r2

r3

bicarbonate-form

0%

10%

20%

30%

40%

50%

0 50 100

% D

OC

rem

oval

time (min)

r0

r1

r2

r3

bicarbonate-form

0%

10%

20%

30%

40%

50%

0 50 100

% D

OC

rem

oval

time (min)

r0

r1

r2

r3

chloride-form