Ion-exchange (IX): arsenic and chromium removal from

425 Pages·2015·4.33 MB·English

by  Behrang Pakzadeh

UNLV Theses, Dissertations, Professional Papers, and Capstones
5-2010
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Behrang Pakzadeh
University of Nevada Las Vegas
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Pakzadeh, Behrang, "Ion-exchange (IX): arsenic and chromium removal from brines and removal of
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ION-EXCHANGE (IX): ARSENIC AND CHROMIUM REMOVAL FROM BRINES
AND REMOVAL OF INORGANIC CONTAMINANTS BY SPECIALTY RESINS

by

Behrang Pakzadeh

Bachelor of Science
Sharif University of Technology (SUT), Tehran, Iran
2001

Master of Science
Technical University of Denmark (DTU), Lyngby, Denmark
2006

A dissertation submitted in partial fulfillment
of the requirements for the

Doctor of Philosophy in Engineering
Department of Civil and Environmental Engineering
Howard R. Hughes College of Engineering

Graduate College
University of Nevada, Las Vegas
May 2010
THE GRADUATE COLLEGE

We recommend the dissertation prepared under our supervision by

Behrang Pakzadeh

entitled

Ion-Exchange (IX): Arsenic and Chromium Removal from Brines and
Removal of Inorganic Contaminants by Specialty Resins

be accepted in partial fulfillment of the requirements for the degree of

Doctor of Philosophy in Engineering
Civil and Environmental Engineering

Jacimaria R. Batista, Committee Chair

Thomas C. Piechota, Committee Member

Sajjad Ahmad, Committee Member

Kazem Taghva, Committee Member

Spencer M. Steinberg, Graduate Faculty Representative

Ronald Smith, Ph. D., Vice President for Research and Graduate Studies
and Dean of the Graduate College

May 2010

ii
ABSTRACT

Ion-Exchange (IX): Arsenic and Chromium Removal from Brines and Removal of
Inorganic Contaminants by Specialty Resins

by

Behrang Pakzadeh

Dr. Jacimaria R. Batista, Examination Committee Chair
Associate Professor of Civil and Environmental Engineering
University of Nevada, Las Vegas

Although ion exchange is highly efficient in removing inorganic contaminants,
similar to other water treatment technologies, ion exchange has some drawbacks that
need to be studied further. Three issues related to drawbacks of ion-exchange resins in
water treatment were addressed in this research. The first issue was the influence of
anionic inorganic co-contaminants including nitrate, Cr(VI), Se(VI), and As(V) on the
performances of nitrate and perchlorate specialty (selective) resins in water treatment. It
was found that nitrate can be removed from waters using perchlorate specialty resins, but
the resin is poorly regenerated. Perchlorate was not easily removed from either nitrate or
perchlorate specialty resins. The results showed that simultaneous removal of nitrate and
Cr(VI) is optimal when using nitrate specialty resin. Perchlorate/nitrate specialty resins
were inefficient in removing As(V), but could exchange Cr(VI) or Se(VI). A major issue
realized from this research is the accumulation of co-contaminants in specialty resins and
their release during resin regeneration. Such a release may deem waste regenerant brines
hazardous, significantly affecting disposal costs. The presence of the co-contaminant
ions affected the run length and the brine composition when perchlorate or nitrate
iii
specialty resins were used. Brine treatment is a serious challenge for IX water industry
when removing arsenic (V) or chromium (VI) from drinking water.
Arsenic (V) removal from brines using ferric chloride was the second issue of this
research. The optimum pH range for the process was found to be 4.5-6.5. Higher brine
alkalinity affected coagulation because it commands larger amounts of acid to lower the
pH to the desired level. Increasing ionic strength slightly enhanced the arsenic (V)
removal efficiency. For arsenic (V) concentrations typical in ion exchange brines and to
achieve a remaining As (V) concentration of 5 mg/L, Fe/As molar ratios varying from 1.3
to 1.7 are needed at operating pH values of 5.5 to 6.5. The Fe/As ratios needed to treat
brines are significantly lower than those used to treat drinking waters. Solids
concentration varying from 2 to 18 mg/L were found.
The third issue of this research was chromium removal from IX brines. Optimum pH
range for the process was found to be 8-10.3. The chromium removal efficiency
improved only slightly when the ionic strength increased from 0.1 M to 1.5 M. For
chromium (VI) concentrations typically found in IX brines, a CaS /Cr(VI) molar ratio
5
varying from 0.6 to 1.4 was needed to obtain a final chromium concentration below 5
mg/L. The maximum total chromium removal efficiencies were obtained at reducing
conditions when oxidation reduction potentials of the brines were between -0.1 to 0 V.
Solids concentrations varying from 0.2 to 1.5 g/L were found. The results of this research
have direct application to the treatment of residual wastes brines containing chromium.

iv
AKNOWLEDGEMENTS
I would like to thank Dr. Jacimaria R. Batista, the committee chair, for her extensive
effort in advising me in my dissertation during the four years of my Ph.D. studies at the
University of Nevada, Las Vegas (UNLV). I am grateful to Dr. Batista for the
tremendous amount of time that she spent working with me. I want to express my
gratitude to my dissertation examination committee members: Dr. Sajjad Ahmad, Dr.
Spencer M. Steinberg, Dr. Thomas C. Piechota, and Dr. Kazem Taghva. I have enjoyed
working for two years as a teaching assistant for Dr. Ahmad, and want to thank him for
that opportunity. I appreciate all the comments and help from Dr. Steinberg.
The first two years of my studies was fully funded by Basin Water, Inc., Rancho
Cucamonga, California as a research assistantship. I would like to thank Basin Water,
Inc. for the funding and Dr. Batista for allocating this funding to me. The last two years
of my studies was funded by the Department of Civil and Environmental Engineering,
UNLV as a teaching assistantship. I wish to express my gratitude to the people that have
supported my TA funding applications in the department including: Dr. Batista, Dr.
Ahmad, Dr. Nader Ghafoori, and Dr. Edward S. Neumann. I would like to thank Nevada
Power, the Wolzinger Family, Graduate & Professional Student Association (GPSA), and
UNLV for their generous scholarships that have helped me pass through my studies and
focus on my research.
Many people have helped me to edit my dissertation. I would like to express thanks
to Ray A. Wilson for his valuable comments and to Rachel K. Wilson for her time in
editing my write up. I appreciate the help of the UNLV Writing Center, which I found to
be an incredibly useful program that has helped me to become a better writer. My
v
specials thanks go to Natalie Hudson and Carol Turner, who have patiently read my
dissertation and have helped me with my English.
I would like to thank my brothers, Behrooz and Bobby, who have supported me
mentally through this hardship, for those wonderful times that we have had together. I
want to show my gratitude to Bobby for providing me with a nice house for my stay
during my studies. I would like to thank my friends at UNLV for some great times. I
would like to acknowledge the assistance of Jon Becker, Allen Sampson, and Levia
Lanier from the Department of Civil and Environmental Engineering.
I would like to thank my beloved fiancée, Rachel K. Wilson, for lending her enduring
patience, care, and love during my frustrating endeavor. I am deeply grateful to Rachel
for standing by me. I love you, and I am forever yours, faithfully.
I would like to dedicate my dissertation to my wonderful parents, Zahra and Ahmad.
Their deepest desire has been to see me getting an education. My mother has sacrificed a
lot for me, and I would not have my Ph.D without her. She made me persevere when it
was way too hard to continue. I love you so much, and thanks for all that you did for me.

vi
TABLE OF CONTENTS

ABSTRACT ....................................................................................................................... iii

AKNOWLEDGEMENTS................................................................................................... v

TABLE OF CONTENTS .................................................................................................. vii

LIST OF TABLES ............................................................................................................. xi

LIST OF FIGURES ......................................................................................................... xvi

CHAPTER 1 INTRODUCTION ................................................................................. 1
1.1. Background ........................................................................................................... 1
1.2. Issue One: Impact of Co-Contaminants on the Performances of
Perchlorate and Nitrate Specialty Resins .............................................................. 2
1.3. Issue Two: Arsenic Removal from Ion-Exchange Brines Using
Ferric Chloride ...................................................................................................... 5
1.4. Issue Three: Chromium Removal from Ion-Exchange Brines
Using Calcium Polysulfide ................................................................................. 10
1.5. Research Objective and Hypotheses ................................................................... 12

CHAPTER 2 STATE OF KNOWLEDGE ................................................................ 14
2.1. Occurrence, Health Effects and MCL of Inorganic Contaminants
Removed by Ion-Exchange (IX) ......................................................................... 14
2.2. Classification of Ion-Exchange Resins ............................................................... 21
2.3. Selectivity in Ion-Exchange ................................................................................ 25
2.4. Laboratory Ion-Exchange Minicolumn Design .................................................. 32
2.5. Highly Selective (Specialty) and Conventional Ion-Exchange Resins for
Nitrate and Perchlorate Removal ........................................................................ 39
2.6. Regeneration of Conventional, Nitrate Selective and Perchlorate Selective
Resins .................................................................................................................. 47
2.6.1. Regeneration Principles For Conventional and Nitrate Selective Resins .... 48
2.6.2. Regeneration of Perchlorate Selective Resins and Methods to Improve the
Process .......................................................................................................... 50
2.7. Coagulation Principles ........................................................................................ 58
2.7.1. Properties of Particles and Forces at the Solid-Solution Interface .............. 59
2.7.2. Mechanisms of Coagulation ........................................................................ 62
2.8. Adsorption Principles.......................................................................................... 66
2.8.1. Physiochemical and Electrical Properties of Oxide and hydroxide
Surfaces ........................................................................................................ 67
2.8.2. Mechanisms of Adsorption of Anions on oxide and hydroxide surfaces .... 70
2.8.3. Adsorption Isotherms ................................................................................... 74
2.8.4. Adsorption Models....................................................................................... 76
2.8.5. Properties of Ferric Iron as a Coagulant ...................................................... 79
2.9. Arsenic Removal from Brines ............................................................................ 84
vii
2.9.1. Arsenic Health Effects and Chemistry ......................................................... 84
2.9.2. Arsenic Treatment Technologies ................................................................. 90
2.9.3. Mechanisms of Arsenic Removal by Iron Precipitates during
Coagulation ................................................................................................ 102
2.9.4. Arsenic Removal by Ferric Chloride from Drinking Water ...................... 106
2.9.5. Arsenic Removal by Ferric Chloride from Industrial Water:
Ion-Exchange Brines ................................................................................. 113
2.10. Chromium removal from brines...................................................................... 122
2.10.1. Chromium Health effects and chemistry ................................................. 123
2.10.2. Chromium treatment technologies ........................................................... 132

CHAPTER 3 METHODOLOGY ............................................................................ 172
3.1. Work Plan to address Issue One ....................................................................... 172
3.1.1. Experimental Approach ............................................................................. 172
3.1.2. Experimental Procedure for Laboratory Breakthrough Curves
Generation .................................................................................................. 173
3.2. Work Plan to address Issue Two ....................................................................... 184
3.2.1. Experimental Approach ............................................................................. 185
3.2.2. Modeling of Arsenic Removal Using Ferric Chloride by MINEQL+ ....... 189
3.2.3. Laboratory Experiments Procedure ........................................................... 191
3.2.4. Experimental design................................................................................... 194
3.3. Work Plan to address Issue Three ..................................................................... 200
3.3.1. Experimental Approach ............................................................................. 201
3.3.2. Laboratory Set Up and Operation of Batch Tests ...................................... 202
3.3.3. Batch Experiments Procedure .................................................................... 203
3.4. Analytical Methods ........................................................................................... 207
3.5. Analysis of Data ................................................................................................ 212
3.5.1. Introduction ................................................................................................ 212
3.5.2. Data Analysis for Issue One ...................................................................... 213
3.5.3. Data Analysis for Issue Two ...................................................................... 214
3.5.4. Data Analysis for Issue Three .................................................................... 218
3.6. Quality Assurance/Quality Control (QA/QC) .................................................. 222

CHAPTER 4 IMPACT OF INORGANIC ANIONIC CO-CONTAMINANTS
ON PERFORMANCES OF PERCHLORATE AND NITRATE
SPECIALTY ION-EXCHANGE RESINS ........................................ 226
4.1. Abstract ............................................................................................................. 226
4.2. Introduction ....................................................................................................... 227
4.3. Experimental ..................................................................................................... 231
4.3.1. Materials .................................................................................................... 232
4.3.2. Experimental Procedure ............................................................................. 233
4.3.3. Analytical Methods .................................................................................... 239
4.3.4. Cost Analysis ............................................................................................. 240
4.4. Results and Discussion ....................................................................................... 241
4.4.1. Loading and Regeneration for Nitrate Removal .......................................... 241
4.4.2. Loading and Regeneration for Cr(VI) Removal .......................................... 254
viii
4.4.3. Loading and Regeneration for Se(VI) Removal .......................................... 258
4.4.4. Loading and Regeneration for As(V) Removal ........................................... 261
4.5. Implication of the Findings Regarding The Use of Perchlorate and
Nitrate selective Resins in waters with other co-contaminants ........................ 265

CHAPTER 5 REMOVAL OF ARSENIC FROM ION-EXCHANGE
WASTE BRINES WITH FERRIC CHLORIDE ............................... 270
5.1. Abstract ............................................................................................................. 270
5.2. Introduction ....................................................................................................... 271
5.3. Experimental ..................................................................................................... 276
5.3.1. Synthetic Brine Preparation and Reagents ................................................. 276
5.3.2. Experimental Procedure ............................................................................. 277
5.3.3. Analytical Methods .................................................................................... 280
5.3.4. Surface Complexation Modeling ............................................................... 280
5.3.5. Statistical Analysis ..................................................................................... 282
5.4. Results and Discussion ....................................................................................... 283
5.4.1. Effect of pH on As(V) Removal from Brines with Ferric Chloride .......... 283
5.4.2. Effects of Ionic Strength, Initial As(V) Concentration, and Ferric
Chloride Dosage on Removal .................................................................... 285
5.4.3. Two-Layer Surface Complexation Modeling ............................................ 291
5.4.4. Effects of Initial Alkalinity ........................................................................ 297
5.4.5. Sludge Solids Generated from the Coagulation Treatment ....................... 299
5.6. Conclusions ....................................................................................................... 301

CHAPTER 6 REMOVAL OF CHROMIUM FROM ION-EXCHANGE
WASTE BRINES WITH CALCIUM POLYSULFIDE .................... 304
6.1. Abstract ............................................................................................................. 304
6.2. Introduction ....................................................................................................... 305
6.3. Experimental ..................................................................................................... 309
6.3.1. Typical Composition of Actual IX Waste Brine ........................................ 309
6.3.2. Central Composite Experimental Design................................................... 310
6.3.3. Statistical Analysis ..................................................................................... 313
6.3.4. Reagents ..................................................................................................... 314
6.3.5. Coagulation Batch Experiments and Analytical Methods ......................... 315
6.3.6. Batch Experiments to Evaluate the Effects of pH, CaS Dosage,
5
and Initial Cr(VI) Concentration ................................................................ 317
6.3.7. Batch Experiments to Evaluate the Effects of Ionic Strength and
Alkalinity ................................................................................................... 318
6.4. Results and Discussion ....................................................................................... 318
6.4.1. Effect of Ionic Strength .............................................................................. 318
6.4.2. Center Composite Design (CCD) Prediction of the Effects of pH and
Initial Cr(VI) Concentration on Total Chromium Removal ...................... 322
6.4.3. Effects of pH .............................................................................................. 323
6.4.4. CCD Prediction for the Effects of CaS Dosage and Initial Cr(VI)
5
Concentration on Total Chromium Removal ............................................. 327
6.4.5. Effects of Calcium Polysulfide Dosage and Initial Chromium
ix