Table of Contents
Cover
Title Page
Copyright
Dedication
Preface
Acknowledgment
Chapter 1: Ion Exchange and Ion Exchangers: An Introduction
1.1 Historical Perspective
1.2 Water and Ion Exchange: An Eternal Kinship
1.3 Constituents of an Ion Exchanger
1.4 What is Ion Exchange and What is it Not?
1.5 Genesis of Ion Exchange Capacity
1.7 Amphoteric Inorganic Ion Exchangers
1.8 Ion Exchanger versus Activated Carbon: Commonalities and Contrasts
1.9 Ion Exchanger Morphologies
1.10 Widely Used Ion Exchange Processes
Summary
References
Chapter 2: Ion Exchange Fundamentals
2.1 Physical Realities
2.2 Swelling/Shrinking: Ion Exchange Osmosis
2.3 Ion Exchange Equilibrium
2.4 Other Equilibrium Constants and Equilibrium Parameters
2.5 Electrostatic Interaction: Genesis of Counterion Selectivity
2.6 Ion Exchange Capacity: Isotherms
2.7 The Donnan Membrane Effect in Ion Exchanger
2.8 Weak-Acid and Weak-Base Ion Exchange Resins
2.9 Regeneration
2.10 Resin Degradation and Trace Toxin Formation
2.11 Ion Exclusion and Ion Retardation
2.12 Zwitterion and Amino Acid Sorption
2.13 Solution Osmotic Pressure and Ion Exchange
2.14 Ion Exchanger as a Catalyst
Summary
References
Chapter 3: Trace Ion Exchange
3.1 Genesis of Selectivity
3.2 Trace Isotherms
3.3 Multi-Component Equilibrium
3.4 Agreement with Henry's Law
3.5 Multiple Trace Species: Genesis of Elution Chromatography
3.6 Uphill Transport of Trace Ions: Donnan Membrane Effect
3.7 Trace Leakage
3.8 Trace Fouling by Natural Organic Matter
3.9 Ion Exchange Accompanied by Chemical Reaction
3.10 Monovalent–Divalent Selectivity
3.11 Entropy-Driven Selective Ion Exchange: The Case of Hydrophobic Ionizable Organic Compound (HIOC)
3.12 Linear Free Energy Relationship and Relative Selectivity
3.13 Simultaneous Removal of Target Metal Cations and Anions
3.14 Deviation from Henry's Law
3.15 Tunable Sorption Behaviors of Amphoteric Metal Oxides
3.16 Ion Sieving
3.17 Trace Ion Removal
Summary
References
Chapter 4: Ion Exchange Kinetics: Intraparticle Diffusion
4.1 Role of Selectivity
4.2 State of Water Molecules inside Ion Exchange Materials
4.3 Activation Energy Level in Ion Exchangers: Chemical Kinetics
4.4 Physical Anatomy of an Ion Exchanger: Gel, Macroporous and Fibrous Morphology
4.5 Column Interruption Test: Determinant of Diffusion Mechanism
4.6 Observations Related to Ion Exchange Kinetics
4.7 Interdiffusion Coefficients for Intraparticle Diffusion
4.8 Trace Ion Exchange Kinetics
4.9 Rectangular Isotherms and Shell Progressive Kinetics
4.10 Responses to Observations in Section 4.6
4.11 Rate-Limiting Step: Dimensionless Numbers
4.12 Intraparticle Diffusion: From Theory to Practice
Summary
References
Chapter 5: Solid- and Gas-Phase Ion Exchange
5.1 Solid-Phase Ion Exchange
5.2 Coagulant Recovery from Water Treatment Sludge
5.3 Gas Phase Ion Exchange
5.4 CO
2
Gas as a Regenerant for IX Softening Processes: A Case Study
Summary
References
Chapter 6: Hybrid Ion Exchange Nanotechnology (HIX-Nanotech)
6.1 Magnetically Active Polymer Particles (MAPPs)
6.2 Hybrid Nanosorbents for Selective Sorption of Ligands (e.g., HIX-NanoFe)
6.3 HAIX-NanoZr(IV): Simultaneous Defluoridation and Desalination
6.4 Promise of HIX-Nanotechnology
Summary
References
Chapter 7: Heavy Metal Chelation and Polymeric Ligand Exchange
7.1 Heavy Metals and Chelating Ion Exchangers
7.2 Polymeric Ligand Exchange
Summary
References
Chapter 8: Synergy and Sustainability
8.1 Waste Acid Neutralization: An Introduction
8.2 Improving Stability of Anaerobic Biological Reactors
8.3 Sustainable Aluminum-Cycle Softening for Hardness Removal
8.4 Closure
Summary
References
Appendex A: Commercial Ion Exchangers
Appendex B: Different Units of Capacity, Concentration, Mass, and Volume
B.1 Capacity
B.2 Concentration (Expressed as CaCO
3
)
B.3 Mass
B.4 Volume
Appendex C: Table of Solubility Product Constants at 25 °C
Appendex D: Acid and Base Dissociation Constants at 25 °C
ATOMIC WEIGHTS OF THE ELEMENTS
Index
End User License Agreement
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Guide
Cover
Table of Contents
Preface
Begin Reading
List of Illustrations
Chapter 1: Ion Exchange and Ion Exchangers: An Introduction
Figure 1.1 Number of patents per year for “anion exchange” and “cation exchange” per a Google Patents search.
Figure 1.2 Shape of water molecules (a) Dipolar O−H bonds with electronegativity values; (b) Electronic structure with tetrahedral arrangement.
Figure 1.3 Interaction of water molecules through association of four hydrogen atoms with each oxygen atom.
Figure 1.4 Anomalous boiling point behavior of H
2
O in Group VIA hydrides.
Figure 1.5 Illustration of ion–dipole interaction: Sodium chloride (ionic compound) solution in water (polar solvent).
Figure 1.6 Schematic illustration of a strong acid cation exchange resin bead where matrix/framework is represented by R, fixed coions or functional groups by −SO
3
−
and counterions/exchanging ions by Na
+
.
Figure 1.7 Charge acquisition through isomorphic substitution of Al for Si (formation of defects of fixed coions in naturally occurring silicates).
Figure 1.8 Zeolite A (a) and faujasite-type zeolites X and Y (b) formed by sodalite cages.
Figure 1.9 Illustration of molecular sieves for the separation of straight chain organic molecule. Straight chain normal octane molecule (a) passes through the eight-ring aperture of 5A zeolite; branched molecule of isooctane cannot (b).
Figure 1.10 Synthesis of weak-acid cation exchanger by polymerization of sodium methacrylate with divinyl-benzene crosslinking.
Figure 1.11 Synthesis of strong-acid cation exchange resin by polymerization of styrene with cross linking of divinyl benzene followed by sulfonation.
Figure 1.12 Synthesis of strong-base anion exchange resin through chloromethylation followed by amination with tertiary amine.
Figure 1.13 Synthesis of styrenic weak-base anion exchange resin through chloromethylation followed by amination with secondary amine.
Figure 1.14 (a) Type I and (b) Type II functional groups of SBA resins.
Figure 1.15 Illustration of a typical liquid ion exchange process followed by phase separation.
Figure 1.16 An illustration of facilitated transport in liquid ion exchange for recovering metals using two membrane contactors.
Figure 1.17 Zinc recovery with D2EHPA metal extractant.
Figure 1.18 An illustration of the characteristic features of the modified solvent-impregnated resin (SIR).
Figure 1.19 Illustration of amphoteric ion exchange behavior of polyvalent hydrated oxides.
Figure 1.20 Relative distribution of HFO surface functional groups as a function of pH (p
K
a1
= 6.5, p
K
a2
= 8.8).
Figure 1.21 An illustration of interaction of ligands (e.g., phosphate) with HFO surface functional groups in the presence of chloride.
Note:
LAB* = Lewis acid–base.
Figure 1.22 An illustration of interaction of transition metal cation (e.g., Cu
2+
) with HFO surface in the presence of Ca
2+
.
Figure 1.23 Effluent histories for As(V) and Cu
2+
for a fixed bed column run with GFH. SLV = Superficial Liquid Velocity; EBCT = Empty Bed Contact Time.
Figure 1.24 Illustration of morphologies of different ion exchange materials.
Figure 1.25 A schematic of the cation exchange softening process in a fixed-bed system. The solid line shows the service/sorption cycle and the dashed line represents regeneration with brine.
Figure 1.26 Calcium history of two consecutive service cycles by a strong-acid cation exchange softener.
Figure 1.27 (a) Regeneration curve for exhausted strong-acid cation exchange resin with 5% NaCl; (b) A comparison of regeneration efficiency (Na
+
: Ca
2+
) versus Ca
2+
recovery.
Chapter 2: Ion Exchange Fundamentals
Figure 2.1 Illustration of an ion exchange process showing ion exchange, swelling and coion invasion.
Figure 2.2 Schematic illustration of elastic force vis-à-vis osmotic force in swelling and shrinking of ion exchange resin.
Figure 2.3 Plot showing dependence of swelling on the degree of cross-linking and the counterion valence for a strong-acid cation exchanger.
Figure 2.4 Illustration of an ion exchange process with three different lateral configurations.
Figure 2.5 Illustration of binary equilibrium isotherm plots (
y
A
vs
x
A
) and their relationship with separation factors (Eq. 2.18).
Figure 2.6 Nitrate–chloride equilibrium isotherms at three different electrolyte concentrations.
Figure 2.7 Plots of sulfate–chloride isotherms at three different electrolyte concentrations showing impact of electrolyte concentration on separation factors.
Figure 2.8 An illustration of the ion exchange half reactions through formation and splitting of the solvated ion pair. (a) One half of reaction where A
+
gets attached with R
−
; (b) The other half of reaction, that is, splitting of R
−
B
+
.
Figure 2.9 Chromatograms of different anions in ion chromatography elution with anion exchange resin.
Figure 2.10 Chromatograms of different cations in ion chromatography elution with cation exchange resin.
Figure 2.11 Plot showing dependence of ion exchange selectivity on hydrated ionic radii for monovalent cations.
Figure 2.12 Diagram of the batch technique for testing isotherms.
Figure 2.13 Illustration of determination of ion exchange capacity using regenerable mini-column method, where service runs and regeneration runs are represented by solid and dashed lines, respectively and
.
Figure 2.14 Illustration of effluent histories for step-feed frontal column run.
Figure 2.15 Illustration of semi-permeable behavior of ion exchange resins due to the presence of fixed charges in the exchanger phase: (a) cation exchanger with fixed negative charges; (b) anion exchanger with fixed positive charges.
Figure 2.16 Effect of crosslinking percentage on coion invasion.
Figure 2.17 Formation of cyclic structure of two neighboring carboxylate functional groups through hydrogen bonding.
Figure 2.18 (a) Illustration of pH titration curves of strong-acid and weak-acid cation exchange resins. (b) Illustration of pH titration curves of strong-base and weak-base anion exchange resins.
Figure 2.19 Experimental pH titration curves of weak-acid cation exchange resins with and without NaCl. The counterion uptake is plotted versus the pH of the aqueous phase. The ratio of solution volume to resin dry-weight is 150 mL : 1 g.
Figure 2.20 Experimental pH titration curves of weak-base anion exchange resins with and without NaCl. The counterion uptake is plotted versus the pH of the aqueous phase. The ratio of solution volume to resin dry-weight is 150 mL : 1 g.
Figure 2.21 Gradual deprotonation of a cation exchanger with weak iminodiacetate functional group with an increase in pH (R represents repeating styrene matrix).
Figure 2.22 A schematic depicting the most commonly used ion exchange system configuration in environmental separation to remove target solute “A” from the solution and reuse of the ion exchanger.
Figure 2.23 A quantitative measure of various interactions in ion exchange-type sorption processes.
Figure 2.24 Regeneration of metal oxides exhausted by anionic ligands through pH swings.
Figure 2.25 A plot of experimentally determined PCP
−
/Cl
−
separation factor values against dielectric constants of the solution phase illustrating the effect of co-solvent on PCP
−
desorption.
Figure 2.26 Concentration profile of desorbed PCP
−
during separate regenerations with (a) 5% NaCl in methanol/water; (b) 5% NaCl in water; and (c) 100% methanol only.
Figure 2.27 A simple schematic of a dual-temperature process illustrating both sorption and desorption of A from the feed through alteration of temperature from
T
2
to
T
1
.
Figure 2.28 Desorption of Ca
2+
from a mixture of 2.5 M NaCl + 0.01 M CaCl
2
using a polymethacrylic resin (KB-4). Bed volume = 180 mL.
Figure 2.29 Iodide (I
−
) enrichment during a cyclic process with a strong-base anion exchange resin at
T
1
= 15
°
C and
T
2
= 75
°
C.
Figure 2.30 Degradation of Type 1 quaternary ammonium functional group in two possible pathways: (a) S
N
2 hydroxyl addition, (b) Hoffman degradation.
Figure 2.31 NDMA formation by chlorination of DMA suggested by Mitch and Sedlak.
Figure 2.32 Separation of citric acid and its salts from a fermentation broth in a chromatographic column with water as the eluent.
Figure 2.33 Breakthrough concentration curves for separation of nitric acid and nitrates. Column loadings: 110 mL strong-acid cation exchange resin AV-17 (Russia). Flow rate:
.
Figure 2.34 Experimental effluent concentration history in separation of NaCl from glycerol and polyglycerols by ion retardation. Feed: 12.5% (w/w) glycerol, 6.2% (w/w) polyglycerols, 6% (w/w) NaCl; temperature 70 °C; resin: Retardion 11A8.
Figure 2.35 A typical amino acid with two acid dissociation constants or p
K
a
values.
Figure 2.36 Overall separation factor values of phenylalanine relative to sodium as a function of pH for a cation exchange resin.
Figure 2.37 Reduction in osmotic pressure of sodium chloride following passage through ion exchangers pre-saturated with divalent ions.
Figure 2.38 (a) Schematic showing exchange of chloride with sulfate in an anion exchanger. (b) Sulfate elution profile with a feed chloride solution of 560 meq/L. (c) Evidence of osmotic pressure reduction through chloride–sulfate exchange.
Figure 2.39 The acid-catalyzed inversion of sucrose to glucose and fructose.
Figure 2.40 Hydrolysis of alkyl halide and carbamate.
Figure 2.41 Effect of pH on hydrolysis rate constants of synthetic organic pesticides.
Chapter 3: Trace Ion Exchange
Figure 3.1 Plot of different types of isotherms (a) linear, (b) rectangular, (c) favorable or convex upward, and (d) unfavorable or concave upward.
Figure 3.2 Effluent histories of As(V) for three different trace arsenic feed in fixed bed column runs using strong-base anion exchanger (IRA-958) under identical conditions.
Figure 3.3 Typical ion chromatogram for some common anions.
Figure 3.4 A schematic illustrating occurrence of chromatographic peaks of ions A and B. Note: The baseline conductivity is due to the eluent. The lower peak or “water dip” at
t
m
is caused by the lower conductivity solvent of the sample, for example, water, being pushed out of the column.
Figure 3.5 Illustration of separation of dilute CuCl
2
using a permeable membrane.
Figure 3.6 Illustration of separation of dilute CuCl
2
using a cation exchange membrane through Donnan dialysis (cation exchange membrane is impermeable to
).
Figure 3.7 (a) An example structure of fulvic acid (L) and (b) a generalized structure of fulvic acid.
Figure 3.8 Gradual release of NaOH from anion exchange resin-bound NOM imparting high conductivity during the rinsing step.
Figure 3.9 An illustration of the accumulation of the excess carboxylate groups in the outer periphery with concomitant cation exchange properties and anion rejection by the Donnan exclusion effect.
Figure 3.10 Functional groups of three commercially available cation exchangers, namely, (a) carboxylate, (b) aminophosphonate, and (c) iminodiacetate with high divalent cation selectivity in sodium form.
Figure 3.11 A cation exchanger in sodium form where in Case 1 there are two exchange sites in close proximity to each other; and in Case 2 there is only local exchange site.
Figure 3.12 The effect of resin matrix on the divalent/monovalent
selectivity of quaternary amine resins at 5.0 meq/L total aqueous phase concentration.
Figure 3.13 The effect of resin matrix on the divalent/monovalent
selectivity of tertiary amine resins.
Figure 3.14 The effect of amine functionality on the divalent/monovalent
selectivity of polystyrene resins.
Figure 3.15 The effect of amine functionality on the divalent/monovalent
selectivity of polyacrylic resins.
Figure 3.16 Strong-base anion exchange resins with trimethyl, triethyl, tripropyl, and tributyl functional groups.
Figure 3.17 (a) Sulfate (50 BVs) and nitrate (>250 BVs) breakthrough for styrene–divinylbenzene resin with tributyl quaternary ammonium groups (nitrate-selective resin); (b) sulfate (150 BVs) and nitrate (150 BVs) breakthrough for styrene–divinylbenzene resin with trimethyl quaternary ammonium groups (Type I Anion exchange resin).
Figure 3.18 Comparison of chromate/sulfate isotherm (23 ± 2 °C) at pH 4.0 between the new resin (tripropyl quaternary ammonium functionality) and IRA-900 (trimethyl quaternary ammonium functionality) under identical conditions.
Figure 3.19 Comparison of chromate/chloride isotherms (23 ± 2 °C) at pH 8.5 between the new resin (tripropyl quaternary ammonium functionality) and IRA-900 (trimethyl quaternary ammonium functionality) under identical conditions.
Figure 3.20 A schematic illustrating an exothermic and enthalpy-driven sorption process.
Figure 3.21 A schematic illustrating NPM–solvent, NPM–matrix, and electrostatic interactions during sorption of the aromatic anion from the aqueous phase.
Figure 3.22 Milliequivalents of PCP
−
uptake onto the anion exchanger versus the corresponding release of Cl
−
into the aqueous phase.
Figure 3.23 (a) Sorption of pentachlorophenol onto ion exchanger and synthetic adsorbent under different pH. (b) Theoretical speciation of the neutral species (PCP
0
) and the anionic species (PCP
−
) as a function of pH.
Figure 3.24 A complete effluent history of PCP
−
and other competing inorganic anions during a fixed-bed column run with IRA-900 in chloride form.
Figure 3.25 The average separation factor (
α
PCP/Cl
) versus the volume fraction of organic solvents in water.
Figure 3.26 Three major factors that govern the thermodynamics of HIOC sorption onto an anion exchanger.
Figure 3.27 PCP
−
/Cl
−
isotherms at three different temperatures for (a) IRA-900 and water; (b) IRA-958 and water; and (c) IRA-900 and methanol/water systems.
Figure 3.28 van't Hoff plots (ln
K
vs 1/
T
) for three different types of isotherms reported in Figure 3.27.
Figure 3.29 van't Hoff plot (ln
K
vs 1/
T
) for sulfonated aromatic anions.
Figure 3.30 (a) Energetics of methane transfer between water and cyclohexane as a control in comparison to transfer of HIOCs between water–ion exchange resin. Enthalpic and entropic changes during PCP
−
or TCP
−
sorption under varying conditions (b–e) and their relationships to methane transfer between cyclohexane and water; (f) represents nitrate–chloride exchange in water with an anion exchanger.
Figure 3.31 Average PCP
−
/Cl
−
separation factor values for two anion exchangers, IRA-900 and IRA-958.
Figure 3.32 A plot of experimentally determined ln
K
values versus log
K
OW
for three chlorophenols.
Figure 3.33 Plot of copper/calcium separation factors for three commercial chelating exchangers versus aqueous phase stability constant of representative ligands of chelating species.
Figure 3.34 Plot of metal/calcium separation factors for a weak-acid cation exchanger (carboxylate functionality) versus aqueous phase metal acetate stability constants.
Figure 3.35 Plot showing relationship of binary separation factors of divalent anionic ligand versus corresponding copper ligand stability constant values.
Figure 3.36 Various constituents of the conceptualized polymeric sorbents for sequential removal of transitional metal cations and anionic ligands.
Figure 3.37 Effluent history of Cu(II) and Cr(VI) with a background of other competing cations and anions from a column run using conceptualized polymeric sorbent.
Figure 3.38 Illustration of gradual progress of sorption process for a favorably sorbed species.
Figure 3.39 Predominance diagram for various Cr(VI) species.
Figure 3.40 Qualitative partitioning of different Cr(VI) species along with other background cations and anions in anion exchanger (fixed positive charge) and in liquid phase, horizontal bars representing relative concentrations.
Figure 3.41 Isotherms for trace chromate in the background of high sulfate concentration for macroporous and gel-type anion exchangers.
Figure 3.42 Isotherms for trace chromate in the background of high chloride concentration for macroporous and gel-type anion exchangers.
Figure 3.43 Isotherms for trace chromate in the presence of high chloride concentration for a macroporous strong-base anion exchanger at acidic and alkaline conditions.
Figure 3.44 (a) Illustration of binding of heavy metal cations and ligands by HFO functionalities at different pH condition; (b) selective binding of metal cations (e.g., Cu
2+
) by HFO doped cation exchanger; (c) selective binding of ligands (e.g.,
) by HFO doped anion exchanger.
Figure 3.45 Results of fixed bed column runs under identical conditions with (a) GFH, (b) HCIX-NanoFe, and (c) HAIX-NanoFe.
Figure 3.46 Result of batch sorption study of As(V) and Cu(II) onto ZrO
2
-doped cation exchanger (HCIX-NanoZr).
Figure 3.47 Effect of ionic radius of large cations on the exchange capacity. Note: For Na
+
and Ca
2+
the cation exchange capacity is 100%.
Figure 3.48 Effluent uranium levels during the virgin exhaustions of a bed of pure SBA resin at pH 4.3.
Figure 3.49 Uranium elution by 2.0 N and 3.0 N NaCl during the first concurrent regeneration of a pure SBA resin bed exhausted to 30,000 BV; regeneration level 10 eq Cl
−
/eq resin (36 lb NaCl/ft
3
resin).
Figure 3.50 Schematic of radium removal by a strong-acid cation exchanger loaded in sodium form with barium sulfate precipitates.
Figure 3.51 The structure of boron selective resins.
Note
: The repeating polyol structure is used for boron chelation.
Figure 3.52 A schematic illustrating the uptake into and desorption from a boron-selective resin with polyol functional groups.
Figure 3.53 Twenty-four hours perchlorate–chloride binary isotherms at 20 °C comparing three polystyrene resins with varying alkyl chain lengths of the quaternary amine functional group. The perchlorate separation factors are in parentheses.
Figure 3.54 Effect of temperature on elution of perchlorate from a polystyrene resin using 1 N chloride solutions. Perchlorate–chloride separation factors,
α
values, are given for each temperature.
Figure 3.55 Structures of ibuprofen (e.g., tylenol), diclofenac (e.g., NSAID), salicylic acid (e.g., topical skin products), and sulfamethoxazole (e.g., antibiotic, Bactrim).
Figure 3.56 Coremoval of diclofenac and phosphate from fresh urine using hybrid anion exchange resin. Mixing conditions: 2 h at 200 rpm. Initial concentrations: 0.204 mmol/L diclofenac, 704 mg P/L phosphate.
Figure 3.57 (a) Skid-mounted HAIX-NanoFe treatment columns at Lake Isabella, CA for EPA evaluation; (b) influent and effluent data for concurrent uranium and arsenic removal by HAIX-NanoFe from the skid-mounted HAIX-NanoFe columns.
Figure 3.58 Comparison of phosphate isotherms for HAIX at two different background sulfate concentrations, all other conditions remaining identical.
Figure 3.59 Phosphate effluent histories during two consecutive runs with secondary wastewater from the Bethlehem WWTP (Bethlehem, PA, USA) using “virgin” HAIX (Run 1) and “regenerated” HAIX (Run 2).
Figure 3.60 Phosphate elution profiles during regeneration of HAIX resin with high phosphate recovery (>95%) in 12 bed volumes.
Figure 3.61 Isotherm of HAIX and activated alumina (AA) for sorption of As(III) species.
Chapter 4: Ion Exchange Kinetics: Intraparticle Diffusion
Figure 4.1 Illustration of ion exchange reaction and transport of counterions between the solution (liquid phase) and the ion exchanger (solid phase) where counterion B
+
is being gradually replaced by A
+
.
Figure 4.2 (a) Fractional uptake versus time plot for isotopic exchange of S*O
4
2−
/SO
4
2−
on anion exchanger IRA-458 and IRA-67 under identical experimental and hydrodynamic conditions.
Source:
Liberti 1983 [1]. Reproduced with permission of Springer. (b) Fractional uptake versus time plot for PCP
−
/Cl
−
exchange on anion exchanger IRA-900 for two different stirring speeds.
Figure 4.3 Schematic representation of different types of water molecules inside a cation exchanger.
Figure 4.4 Plot showing the typical relation between intraparticle diffusivity and internal porosity of an ion exchanger bead.
Figure 4.5 Experimental results of resin swelling of a chelating ion exchanger with iminodiacetate functional groups in the presence of Ca(II) or Cu(II) solutions.
Figure 4.6 Schematic illustrating the relative increase in osmotic pressure of the chelating exchanger as it transitions from H-form to Cu-form and to Ca-form.
Figure 4.7 Effects of temperature on the fractional uptake profile of Ni(II) by a chelating ion exchanger in Na-form containing aminophosphonic functional groups.
Figure 4.8 Arrhenius plot for Na/Ni exchange showing influence of temperature on ion exchange rate constant.
Figure 4.9 Tunneling electron microphotographs (TEM) of a gel (L) and macroporous (R) anion exchanger.
Figure 4.10 (a) Schematic representation of a macroporous particle containing microgels, where intraparticle diffusion is the rate limiting step and (b) explanation of diffusion of counterions
and
in parallel through microgels and macropores.
Figure 4.11 Visual comparison between spherical ion exchange resin beads and ion exchange fibers.
Figure 4.12 Schematic illustration of radial conversion during uptake for a spherical resin bead and a cylindrical ion exchange fiber.
Figure 4.13 A schematic illustration of intraparticle diffusion control through an interruption test presenting concentration profile changes within an ion exchanger bead (a) before interruption; (b) after interruption; (c) immediately after restart; (d) long after restart; (e) their slopes at different stages of interruption test; (f) concentration profiles for liquid-film diffusion control step (i.e., no change in concentration gradient within the exchanger bead before and after interruption).
Figure 4.14 Plot of PCP
−
concentration versus bed volumes. There is a significant drop in PCP
−
concentration immediately after restart following a 24-h column interruption. This concentration profile is demonstrative of intraparticle diffusion being the rate-limiting step.
Figure 4.15 Plot of
t
1/2
versus equilibrium Ni concentration for Ni uptake by a chelating ion exchanger from solution containing Ni in presence of much higher Na
+
concentration.
Figure 4.16 Plot of effective intraparticle diffusivity versus octanol–water partition coefficient for three chlorophenols.
Figure 4.17 Fractional uptake profiles of PCP
−
versus time for gel-type anion exchanger at two background chloride concentrations.
Figure 4.18 Fractional uptake profiles of PCP
−
versus time for the macroporous anion exchanger at two background chloride concentrations.
Figure 4.19 Plot of intraparticle diffusion coefficient of sodium (
) versus concentration of sodium chloride (NaCl) solution for a strong-acid gel type cation exchanger in Na
+
-form.
Figure 4.20 Photographic testimony of shrinking core ion exchange kinetics for Ca
2+
–H
+
exchange for Amberlite IRC-84 (weak-acid cation exchanger) in 1 M HNO
3
solution.
Figure 4.21 Autoradiograph of Ionac XAX 1284 as a function of time during sorption of plutonium(IV) from 7.5 M nitric acid: (a) 1 h, (b) 7 h, (c) 24 h, (d) 48 h, (e) 336 h, (f) 547 h.
Figure 4.22 Graphical presentation for variations in interdiffusion coefficients with respect to the composition of the ion exchanger; when
,
tends to be equal to
.
Figure 4.23 (a) Schematic representation of a macroporous particle containing microgels, where intraparticle diffusion is the rate limiting step, (b) explanation of coupled diffusion of counterions PCP
−
and Cl
−
in parallel through microgels and macropores.
Figure 4.24 Binary isotherms for chlorophenol–chloride for three different chlorophenols at pH = 8.5 where they all exist as monovalent anions.
Figure 4.25 Fractional uptake of three different chlorophenates versus the square root of time for anion exchanger IRA-900.
Figure 4.26 Computed effective intraparticle diffusivities plotted against chlorophenate–chloride separation factors (
).
Figure 4.27 Illustrative plots of rectangular and Langmuir isotherms.
Figure 4.28 Schematic illustrations of concentration changes for A and B (counterions) within a spherical macroporous ion exchanger bead, in accordance with shrinking core or shell-progressive kinetics: affinity of A is far greater than affinity of B.
Figure 4.29 Schematic representation of intraparticle transport of counterion A inside a spherical ion exchanger bead presented with exchangeable ion in B-form based on the concept of (1) first come, first occupy (A-top); (2) last come, first arrive (B-bottom).
Figure 4.30 Schematic explanation of slow kinetics caused by rejection of
ions due to the Donnan coion exclusion effect.
Figure 4.31 Plots of fractional shrinkage of a strong-acid cation exchanger in sodium form and intraparticle diffusion coefficient of sodium (
D
Na
) versus concentration of sodium chloride solution.
Figure 4.32 Schematic illustration of movement of mass transfer zone (MTZ) from inlet to exit along the bed (a) initial stage when MTZ near the inlet and major part of the column unused; (b
)
middle of the cycle when MTZ is in the middle with almost even distribution of used and unused zones;
(
c
)
before exhaustion when MTZ is near the exit and a major part of the column is used (saturated).
Figure 4.33 Schematic illustration showing benefit of reduction of MTZ.
Figure 4.34 RECOFLO short bed IX process.
Figure 4.35 The change in volume or ion exchange capacity with
S
/
R
ratio between a shell–core resin and a standard resin.
Figure 4.36 Comparison of calcium leakage during cation exchange softening in Na-cycle between Purolite C104 and SST104.
Figure 4.37 Illustration of differences in the degree of swelling under different pH conditions between (a) a monofunctional (phosphonic acid group) and (b) a bifunctional (phosphonic acid and sulfonic acid groups) ion exchanger with a polystyrene matrix resin.
Figure 4.38 Structure of Diphonix resin. p
K
1
= 1.5, p
K
2
= 2.5, p
K
3
= 7.2, p
K
4
= 10.5 [10].
Figure 4.39 A comparison of Am(III) uptake rate between sulfonated and unsulfonated Diphonix resins at acidic pH (∼2).
Figure 4.40 Comparison of As(V) fractional uptake during batch kinetic tests between a hybrid anion exchanger (HAIX) and a hybrid polymeric sorbent, both containing iron oxide nanoparticles.
Figure 4.41 Postulated intraparticle transport mechanisms of As(V) inside the two host materials with HFO nanoparticles.
Chapter 5: Solid- and Gas-Phase Ion Exchange
Figure 5.1 (a) Calcium sulfate dissolution and removal with gradual addition of cation exchange resins in Na-form. (b) Calcium sulfate dissolution and removal with gradual addition of cation and anion exchange resins in H- and OH-form, respectively.
Figure 5.2 Conceptualized two-step process illustrating the sequential desorption of toxic metals from contaminated soils followed by uptake onto the chelating ion exchanger, releasing CaCl
2
/NaCl for reuse.
Figure 5.3 (a) Electron micrograph of the composite IDA membrane. (b) Schematic of microbeads in a fibrous network of PTFE. (c) Cloth-like configuration.
Figure 5.4 Copper(II) recovery from the ion-exchange sites of bentonite clay during the cyclic process.
Figure 5.5 Conceptualized heavy metal decontamination process using a CIX sheet, where heavy metals are continuously separated from sludge and concentrated in the regeneration tank.
Figure 5.6 Dissolved copper and calcium concentration during the recovery process at pH = 9.0 for oxalate concentration of 4000 mg/L.
Figure 5.7 Cumulative copper and calcium recovery with increase in number of cycles at alkaline pH.
Figure 5.8 Dissolved Organic Carbon (DOC) and Al (III) in the AWTP sludge at varying pH levels.
Source:
Prakash and SenGupta 2003 [18]. Reproduced with permission of American Chemical Society. (a) A general schematic of Donnan membrane process for alum recovery from water treatment residuals.
Source:
Reprinted with permission from SenGupta and Prakash 2002 [20]. (b) Underlying principles of selective alum recovery using Donnan membrane process with cation exchange membrane.
Figure 5.9 Visual comparison of the clarifier sludge from the AWTP (a), recovered alum coagulant after acid digestion (b) and the recovered alum by the Donnan membrane process (c).
Figure 5.10 Distribution of different species present in the recovered alum by Donnan membrane process.
Figure 5.11 Aluminum recovery from AWTP residuals during Donnan membrane process: (a) decrease in Al concentration in feed; (b) percentage recovery and increase in Al concentration in recovery solution.
Figure 5.12 Fe(III) recovery from ferric chloride based WTR from Baxter Water Treatment Plant during Donnan membrane process: (a) decrease in Fe concentration in feed; (b) percentage recovery and increase in Fe concentration in recovery solution.
Figure 5.13 Visual Comparison of recovered ferric coagulant from Baxter Plant residuals by Acid digestion process (a) and Donnan membrane process (b).
Figure 5.14 Isobaric curves of ion exchanger Dowex-1 × 6 (OH-ionic form) for water content at different relative humidity.
Figure 5.15 Thermogravimetric mass uptake of water, water with CO
2
, with regeneration under N
2
at 150 °C.
Figure 5.16 Comparison of experimental and predicted concentration histories for a mixture of SO
2
and CO
2
.
Figure 5.17 Equilibrium isotherms of ethylamine for MP-type and gel-type H-form resins.
Figure 5.18 Experimental uptake curves (i.e., plot of fractional uptake,
F
, versus time), for ethylamine on macroporous resin (H
+
-form) for different particle sizes.
Figure 5.19 Half-time experimental uptake rate data of ethylamine for the macroporous resin for different particle sizes.
Figure 5.20 Ion exchangers in different physical forms. (a) Granular and fibrous forms (diameter of granular ion exchanger = 0.5 mm). (b) Nonwoven needle punctured Fiban material (A-top). (c) Placing ion exchange canvas in filtering chamber of frame type (RIF) ion exchange filter, top view (B-bottom).
Figure 5.21 Isobaric curves of ion exchanger Fiban K-1 (H
+
-form). Experimental values and modeling values.
Figure 5.22 (a) Breakthrough and sorption curve of ammonia on strong-acid cation exchanger (sulfonic acid functionality) Fiban K-1 (H
+
-form) at relative humidity of 7.5–85%.
T
= 25 °C,
v
= 0.09 m/s, [NH
3
] = 17 mg/m
3
, thickness of filtering layer = 3 mm (top); (b) Breakthrough and sorption curves of ammonia on carboxylic weak-acid cation exchanger Fiban K-4 (H
+
-form) at various relative air humidity levels.
T
= 25 °C,
v
= 0.08 m/s, [NH
3
] = 18 mg/m
3
, thickness of filtering layer = 6 mm (B-bottom).
Figure 5.23 Breakthrough curve of H
2
S on fibrous catalyst (Fiban AK-22 parent material). C
0
(H
2
S) = 60 mg/m
3
; thickness of single catalyst layer = 3 mm; catalyst contained 0.18 mmol Fe/g.
Figure 5.24 A schematic illustrating the possible use of CO
2
-rich stack gas as a regenerant.
Figure 5.25 Laboratory setup depicting the CO
2
-sparged snowmelt system used in the regeneration of both fiber and resin ion-exchange materials.
Figure 5.26 Fixed-bed column runs for hardness removal using two different ion-exchange materials under otherwise identical conditions: (EBCT – empty bed contact time; SLV – superficial liquid velocity).
Figure 5.27 Effluent calcium concentration profiles for (a) IX-fibers and (b) resins during CO
2
-sparged snowmelt regeneration at different carbon dioxide partial pressures.
Figure 5.28 Effluent calcium concentration profiles for IX-fibers and IX resins during CO
2
-sparged snowmelt regeneration at different carbon dioxide partial pressures.
Figure 5.29 Schematic illustrating the difference in desorption mechanisms between (a) resin beads and (b) IX-fibers.
Chapter 6: Hybrid Ion Exchange Nanotechnology (HIX-Nanotech)
Figure 6.1 (a) A spherical ion exchanger bead with conventional composition variables; (b) A hybrid ion exchanger (HIX) bead with ZrO
2
nanoparticles dispersed within the gel phase.
Figure 6.2 Favorable properties of some metal and metal oxide nanoparticles.
Figure 6.3 A schematic of a hybrid ion exchanger.
Figure 6.4 Predominance diagram of different species of Fe and Fe oxides.
Figure 6.5 Steps involved in the preparation of MAPPs with a cation exchanger.
Figure 6.6 A schematic of the batch reactor used for the synthesis of MAPPs.
Figure 6.7 Enlarged view of magnetized Purolite C145 polymer beads (20 × magnification). Physical configurations of the particles were unchanged following magnetization.
Figure 6.8 X-ray diffractograms and characteristic peaks of (a) sliced magnetized polymeric particle (Purolite C145) and (b) magnetite standard.
Figure 6.9 Comparison of responses to a laboratory magnet for four types of Diphonix Polymer beads: (a) no treatment, and dispersed with (b) Fe(II) hydroxide, (c) Fe(III) hydroxide, and (d) magnetite.
Figure 6.10 Experimentally determined specific magnetic susceptibility of various magnetized polymeric beads.
Figure 6.11 Copper sorption capacities of magnetized metal-selective DOW 3N polymer beads over 15 consecutive sorption–desorption cycles.
Figure 6.12 Specific magnetic susceptibilities of the same DOW 3N polymer beads in Figure 6.11 over 15 cycles.
Figure 6.13 Comparison of batch kinetic test results for zinc removal between parent and magnetized Diphonix resins.
Figure 6.14 Illustration of a three-step procedure to disperse both crystalline and amorphous HFO nanoparticles inside polymeric cation exchange beads to create HCIX-NanoFe(III).
Figure 6.15 Illustration of the two-step procedure for dispersing hydrated ferric oxide (HFO) particles inside anion exchange resins to create HAIX-NanoFe(III).
Figure 6.16 Photomicrograph of HFO-loaded (a) hybrid cation exchange resin (left) and (b) hybrid cation exchange resin (right).
Figure 6.17 SEM images of (a) freshly precipitated HFO (100,000×), (b) parent gel type cation exchanger (40,000×) and (c) hybrid cation exchange resin loaded with HFO nanoparticles (40,000×).
Figure 6.18 SEM images of (a) parent gel type anion exchanger (15,000×) and (b) gel hybrid anion exchange resin loaded with HFO nanoparticles (25,000×).
Figure 6.19 SEM image of (a) parent macroporous anion exchanger (20,000×) and (b) macroporous hybrid anion exchange resin loaded with HFO nanoparticles (20,000×).
Figure 6.20 Tunneling electron micrograph (TEM) image of a macroporous hybrid anion exchanger loaded with HFO nanoparticles.
Figure 6.21 Comparison of As(V) effluent histories between a strong-base anion exchanger (IRA-900) and HAIX-NanoFe(III) under identical conditions.
Figure 6.22 Comparison of As(III) effluent histories between a strong-base anion exchanger (IRA-900) and HAIX-NanoFe(III) under identical conditions.
Figure 6.23 Comparison of As(V) effluent histories between HCIX-G-NanoFe(III) and HAIX-G-NanoFe(III) for two separate column runs under otherwise identical conditions.
Figure 6.24 Depiction of three specific cases presenting the Donnan distribution of arsenate (
) when the membrane is permeable to (Case I) all the ions; (Case II) all the ions except
; and (Case III) all the ions except
.
Figure 6.25 Schematic illustrating (a) enhanced permeation of anions into the hybrid sorbent in the presence of non-diffusible cations (anion exchanger) and (b) exclusion of anions from the hybrid sorbent in the presence of non-diffusible anions (cation exchanger).
Figure 6.26 Dissolved arsenic concentration profile during desorption of HAIX-NanoFe(III) using 2% NaOH and 3% NaCl as the regenerant.
Figure 6.27 Arsenic breakthrough history of an arsenic removal unit at Ashoknagar in West Bengal, India using HAIX-NanoFe(III).
Figure 6.28 (a) Photograph of a plant in Sahuarita, Arizona using LayneRT for arsenic removal and (b) arsenic breakthrough profiles during a pilot run prior to installation (GFO: granulated ferric oxide, MCL: maximum contaminant limit).
Figure 6.29 (a) Photograph of HAIX-F-NanoFe(III) at 10× magnification, (b) SEM image of the surface of the parent fiber at 2000× magnification, and (c) SEM image of the surface of the hybrid fiber at 2000× magnification.
Figure 6.30 (a) SEM image of cross-section of a hybrid anion exchange fiber at 2000× magnification; and (b) energy dispersive X-ray (EDX) mapping of iron along the diameter of the cross-section of the hybrid fiber.
Figure 6.31 (a) Effluent history of arsenate during three consecutive column runs with HAIX-F-NanoFe(III) and (b) Effluent history of perchlorate during three consecutive runs with HAIX-F-NanoFe(III).
Figure 6.32 Arsenate and perchlorate uptake during multiple cycles of sorption–desorption using HAIX-F-NanoFe(III).
4
Figure 6.40 SEM images of Purolite A520E resin before (a) and after (b and c) Donnan effect driven intermatrix synthesis of Pd-polymer-stabilized metal nanocatalysts (Pd-PSMNCs). TEM images (d, e) and size distribution histogram (f) of Pd-PSMNC.
Figure 6.41 Kinetics of bactericidal treatment of
Escherichia coli
-contaminated water with FIBAN-Ag-Co filter.
Chapter 7: Heavy Metal Chelation and Polymeric Ligand Exchange
Figure 7.1 A modified periodic table showing common regulated heavy metals, metalloids and unregulated light metals.
Figure 7.2 Nutritional and inhibitory effects of heavy metal concentrations on living cells/microorganisms.
Figure 7.3 A schematic illustrating various engineered processes for heavy metals separation.
Figure 7.4 An illustration depicting a chelating polymer bead with different covalently attached functional groups.
Figure 7.5 Relationship between copper/calcium separation factors for commercial chelating exchangers and corresponding aqueous-phase stability constant values with representative ligands.
Figure 7.6 Relationship between experimentally determined metal/calcium separation factors for IRC DP-1 and aqueous-phase metal-acetate stability constant values.
Figure 7.7 Experimentally determined Me(II)-Calcium separation factor values as a function of pH for various resins: IRC-718 = iminodiacetate functionality, GT-73 = thiol functionality and XFS 4195 = bispicolylamine functionality.
Figure 7.8 Demonstration of high regeneration efficiency of copper-loaded IRC-718 (iminodiacetate functionality) with 2% HCl.
Figure 7.9 Visual representation of shrinking-core kinetics for copper sorption and regeneration with a chelating ion exchanger.
Figure 7.10 Effects of ethylenediamine and pH on copper/calcium separation factor for IRC-718 (iminodiacetate functionality).
Figure 7.11 Various constituents of a conceptualized polymeric ligand exchanger for selective sorption of an aqueous phase ligand, L
n
−
.
Figure 7.12 Phosphate isotherms for DOW3N-Cu at two different background concentrations (200 and 400 mg/L) of competing sulfate ions.
Figure 7.13 Comparison of phosphate/sulfate (P/S) separation factors for various sorbents.
Figure 7.14 Oxalate effluent histories during column runs with four different sorbents under otherwise identical conditions: SLV, superficial liquid-phase velocity, EBCT, empty bed contact time.
Figure 7.15 General schematic of a fixed-bed column using PLE.
Figure 7.16 Schematic presentation of binding mechanisms of divalent phosphate for different sorbents.
Figure 7.17 Structures of five bidentate anionic ligands: succinate, maleate, phthalate, oxalate, and hydrogen phosphate.
Figure 7.18 Linear free energy relationship (LFER) between the separation factors of DOW 3 N-Cu and the first metal-ligand stability constants.
Chapter 8: Synergy and Sustainability
Figure 8.1 Individual steps involved in the process of acid–base neutralization in the polymer phase for: (a) a weak-acid cation exchange resin and (b) a weak-base anion exchange resin. R
3
N and RCOOH represent the weak-base and weak-acid functional groups, respectively and overbar denotes the resin phase.
Figure 8.2 Photographs under an optical microscope of a gradually swelling weak-acid resin bead from base addition.
Figure 8.3 Kinetics of swelling for a C-104 resin bead in H-form under the action of NaOH solution. Swelling ratio is defined to be the ratio of the volume of swollen resin bead to the un-swollen one.
Figure 8.4 Cyclic swelling and shrinking of a weak-acid cation exchange resin bed (Purolite, C-104) when contacted alternately with 2% NaOH and 2% HCl solutions, respectively over multiple numbers of cycles.
Figure 8.5 Conceptualized reciprocating engine to produce a compressed gas through swelling and shrinking of weak resin.
Figure 8.6 Cyclic deflation (a and c) and inflation (b and d) over two consecutive cycles of a latex membrane covering a container inside which weak-acid cation exchange resin undergoes shrinking and swelling under the action of a solution of acid and base, respectively during a process of neutralization.
Figure 8.7 A schematic illustrating the dissipation of protons and dissolved cationic metal ions in an anaerobic reactor stabilized by the presence of iminodiacetate functionalized polymers.
Figure 8.8 Dissociation and high buffer capacity of IXF Fiban X-1 over a wide range of pH.
Figure 8.9 (a) Experimental apparatus, showing reactor and water displacement apparatus; (b) mother reactor and experimental reactor.
Figure 8.10 Results for organic overloading in the presence of different amounts of iminodiacetate-functionalized IXF. Organic overloading was imparted on the reactors from days 36 to 46 (depicted by the shaded region), with lactose loading increased from the steady-state value of 163 mg/L-d to an overload of 675 mg/L-d and alkalinity loading reduced from a steady-state value of 90.6 mg/L-d as NaHCO
3
to zero. The reactors with IXF maintained methane production during the stress, whereas the reactor without IXF failed (methane generation ceased) and was unable to recover.
Figure 8.11 Demonstration of copper toxicity prevention with iminodiacetate IXF. Here, 8 mg of
(47 µmol) was added to 100 mL anaerobic reactors at days 32 and 33 (indicated by gray shading). Methanogenic activity was immediately impacted by the presence of copper, as shown in the lower figure, with a pH decrease continuing afterwards due to a buildup of organic acids. The reactors with the IXF were able to mitigate the effects of the copper addition and these reactors were able to recover. The reactor without IXF failed (methane output went to zero) and was not able to recover.
Figure 8.12 FIBAN X-1 Nickel exchange capacity after operation in the MPABR for durations of 4, 8, and 12 months. Initial capacity was 1.16 meq/g-fiber and ∼95% capacity remained after one year of operation. Photographs show associated change in fiber color.
Figure 8.13 A schematic of Al
3+
-Ca
2+
exchange followed by Al(OH)
3
precipitation with hydrolysis leading to partial TDS reduction.
Figure 8.14 A process flow diagram for evaluation of SAC-Al hardness removal and regeneration.
Figure 8.15 Effluent history during operation of SAC-Na resin for (a) sodium and calcium during the service cycle; (b) calcium during the regeneration cycle (5% NaCl); and, (c) regeneration efficiency on an equivalent basis.
Figure 8.16 Effluent history of (a) sodium and calcium during SAC-Al treatment over two cycles; and (b) conductivity during SAC-Na and SAC-Al treatment.
Figure 8.17 Effluent history of (a) calcium and (b) pH during SAC-Al regeneration by 3% AlCl
3
.
Figure 8.18 SEM-EDX mapping and spectroscopy of a cation exchange resin bead during Al-cycle operations (a) after exhaustion by synthetic hard water and (b) after regeneration by 3% AlCl
3
.
Figure 8.19 Comparison over multiple cycles of operation of (a) regeneration efficiency between SAC-Na and SAC-Al; (b) ion exchange capacity of SAC-Na and SAC-Al; and (c) mass balance of aluminum regenerant influent and effluent.
Figure 8.20 Schematic overview of water hardness treatment by SAC-Al and regeneration with AlCl
3
.