A STUDY ON THE POLYMORPHISM AND MORPHOGENESIS OF...

A STUDY ON THE POLYMORPHISM AND MORPHOGENESIS

OF CaCO3 SCALE AND ITS PRECLUSION USING A FEW

CHELATING AGENTS - AN ATOMISTIC APPROACH

THESIS SUBMITTED TO THE ANNAMALAI UNIVERSITY IN PARTIAL

FULFILMENT OF THE REQUIREMENTS FOR THE AWARD OF THE DEGREE OF

DOCTOR OF PHILOSOPHY IN CHEMISTRY

By

SHANMUKHA PRASAD GOPI, M.Sc.

DEPARTMENT OF CHEMISTRY

ANNAMALAI UNIVERSITY

ANNAMALAINAGAR - 608 002

TAMIL NADU, INDIA

SEPTEMBER, 2014

ANNAMALAI UNIVERSITY

Dr. V. K. SUBRAMANIAN, M.Sc., Ph.D.

Assistant Professor

Department of Chemistry

Annamalai University

Annamalainagar - 608 002

Tamil Nadu, INDIA E-mail: [email protected]

CERTIFICATE

This is to certify that the thesis entitled “A STUDY ON THE

POLYMORPHISM AND MORPHOGENESIS OF CaCO3 SCALE AND ITS

PRECLUSION USING A FEW CHELATING AGENTS - AN ATOMISTIC

APPROACH” is a bonafide record of research work done by

Mr. SHANMUKHA PRASAD GOPI, Research Scholar, Department of Chemistry,

Annamalai University, Annamalainagar, under my guidance during the

period 2010-2014 and that it has not previously formed the basis for

the award of any degree, diploma, associateship, fellowship or other similar

title to the candidate.

This is also to certify that the thesis represents the independent work of

the candidate.

Place : Annamalainagar

Date : (Dr. V. K. SUBRAMANIAN)

ACKNOWLEDGEMENT

I thank the LORD for showering all the grace on me in steering through the

path of success in every attempt of my life.

First and foremost I wish to express my deepest gratitude and respectful

thanks to my esteemed guide, Dr. V. K. SUBRAMANIAN, Assistant Professor,

Department of Chemistry, Annamalai University, whose continuous, untiring guidance

and supervision, constructive criticism, perfectionist attitude, constant support, kind

treatment and immediate response for all necessities during the period of this

research studies enabled me to carry out this work so as to reach a stage of

completeness.

I would like to express my gratitude to Dr. SP. MEENAKSHISUNDARAM,

Professor and Head, Department of Chemistry, Annamalai University, for providing me

necessary facilities to carry out this work.

I express my heartfelt thanks to Dr. A. MANIMEKALAI,

Dr. C. KARUNAKARAN and Dr. K. PANDIARAJAN, Professors and Former Heads of

Department of Chemistry, Annamalai University.

I owe my deep sense of gratitude to Professor Dr. M. V. RAJASEKHARAN,

School of Chemistry, University of Hyderabad, Hyderabad and UGC NETWORKING

RESOURCE CENTRE for their valuable help by providing the lab facility and access to

analytical instruments.

I would like to thank the, UNIVERSITY GRANTS COMMISION (UGC) New

Delhi, for the financial support through Major research project 37-40/2009 (SR)

dated 12.01.2010.

I would like to express my sincere thanks to Dr. N. V. S. VENUGOPAL,

Associate Professor, GITAM University, Visakhapatnam and

Mr. K. VEERASEKHARAN, Executive engineer, Annamalai University for their kind

help in all possible ways.

I am extremely grateful to my senior Dr. G. SIVASUBRAMANIAN and my

juniors Mr. K. PALANISAMY, Mr. K. SANJEEVRAJ Department of Chemistry,

Annamalai University, for their help.

I would like to owe my sincere thanks to my friends Dr. K. MUTHU,

Mr. M. MUGUGAVELU, Mr. C. SHANMGUM, Mr. K. BALACHANDER,

Mr. B. LOGUNATHAN, Mr. M. VELAUTHAM PILLAI, Mr. B. SUBASH,

Mr. E. SATHYARAJ, Mr. M. KARTHICK and Mr. D. CHINNARAJA Research Scholars,

Annamalai University, for their constant encouragement in all possible ways.

I deem it a great pleasure to put forth my long conceived and well nourished

sense of gratitude to my friends Ms. P. SWAPNA, Mr. N. RAMPRAKASH,

Mr. N. RAJESH, Mr. M. MANMOHAN, Mr. P. ANJANI KUMAR, Mr. N. NAGARJUNA,

Mr. R. BHASKAR, Mr. P. PONMUDI, Mr. R. THANGAVEL, Mr. K. NARENDRA,

Mr. K. PRAVEEN KUMAR, Mr. BALMIKI KUMAR, Mr. MANIKANDAN,

Dr. V. CHENCHAIAH, Dr. S.N. REDDY and Mrs. S. BHUWANESARI GOVINDRAJ,

for their constant encouragement in all possible ways and their whole hearted help

rendered at the time of crisis would be remembered life long..

I would like to owe my sincere thanks to Prof. M. V. R RESEARCH GROUP and

technical staffs Mr. S. KUMAR, Mr. S. LAXMINARAYANA, Mr. S. PAVANKUMAR

and all my friends in SCHOOL OF CHEMISTRY, UNIVERSITY OF HYDERABAD,

HYDERABAD for their constant encouragement.

On a personal note, I Express my sincere gratitude to my parents

Mr. G. SATYARAO and Mrs. G. NAGAMANI for their selfless love, goodwill,

commendable sacrifice and colossal affection which has groomed me up to this level.

I sincerely thank my brother Mr. G. GANESH KUMAR and uncle

Mr. A.S.S. CHINNARAO for their encouragement and affection

I render my sincere thanks to all the TEACHING, NON-TEACHING STAFF

MEMBERS and my ALL FRIENDS Department of Chemistry, Annamalai University for

their kind help.

I thank one and all who have been associated with this work

Place : Annamalainagar (SHANMUKHA PRASAD GOPI)

Date :

ACKNOWLEDGEMENT

I thank the LORD for showering all the grace on me in steering through the

path of success in every attempt of my life.

First and foremost I wish to express my deepest gratitude and respectful

thanks to my esteemed guide, Dr. V. K. SUBRAMANIAN, Assistant Professor,

Department of Chemistry, Annamalai University, whose continuous, untiring guidance

and supervision, constructive criticism, perfectionist attitude, constant support, kind

treatment and immediate response for all necessities during the period of this

research studies enabled me to carry out this work so as to reach a stage of

completeness.

I would like to express my gratitude to Dr. SP. MEENAKSHISUNDARAM,

Professor and Head, Department of Chemistry, Annamalai University, for providing me

necessary facilities to carry out this work.

I express my heartfelt thanks to Dr. A. MANIMEKALAI,

Dr. C. KARUNAKARAN and Dr. K. PANDIARAJAN, Professors and Former Heads of

Department of Chemistry, Annamalai University.

I owe my deep sense of gratitude to Professor Dr. M. V. RAJASEKHARAN,

School of Chemistry, University of Hyderabad, Hyderabad and UGC NETWORKING

RESOURCE CENTRE for their valuable help by providing the lab facility and access to

analytical instruments.

I would like to thank the, UNIVERSITY GRANTS COMMISION (UGC) New

Delhi, for the financial support through Major research project 37-40/2009 (SR)

dated 12.01.2010.

I would like to express my sincere thanks to Dr. N. V. S. VENUGOPAL,

Associate Professor, GITAM University, Visakhapatnam and

Mr. G. RATHINA SAMPATH, Superintendent, Dental college, Annamalai University

for their kind help in all possible ways

I am extremely grateful to my senior Dr. G. SIVASUBRAMANIAN and my

juniors Mr. K. PALANISAMY, Mr. K. SANJEEVRAJ Department of Chemistry,

Annamalai University, for their help.

I would like to owe my sincere thanks to my friends Dr. K. MUTHU,

Mr. M. MUGUGAVELU, Mr. C. SHANMGUM, Mr. K. BALACHANDER,

Mr. B. LOGUNATHAN, Mr. M. VELAUTHAM PILLAI, Mr. B. SUBASH,

Mr. E. SATHYARAJ, Mr. M. KARTHICK and Mr. D. CHINNARAJA Research Scholars,

Annamalai University, for their constant encouragement in all possible ways.

I deem it a great pleasure to put forth my long conceived and well nourished

sense of gratitude to my friends Ms. P. SWAPNA, Mr. N. RAMPRAKASH,

Mr. N. RAJESH, Mr. M. MANMOHAN, Mr. P. ANJANI KUMAR, Mr. N. NAGARJUNA,

Mr. R. BHASKAR, Mr. P. PONMUDI, Mr. R. THANGAVEL, Mr. K. NARENDRA,

Mr. K. PRAVEEN KUMAR, Mr. BALMIKI KUMAR, Mr. MANIKANDAN,

Dr. V. CHENCHAIAH, Dr. S.N. REDDY and Mrs. S. BHUWANESARI GOVINDRAJ,

for their constant encouragement in all possible ways and their whole hearted help

rendered at the time of crisis would be remembered life long..

I would like to owe my sincere thanks to Prof. M. V. R RESEARCH GROUP and

technical staffs Mr. S. KUMAR, Mr. S. LAXMINARAYANA, Mr. S. PAVANKUMAR

and all my friends in SCHOOL OF CHEMISTRY, UNIVERSITY OF HYDERABAD,

HYDERABAD for their constant encouragement.

On a personal note, I Express my sincere gratitude to my parents

Mr. G. SATYARAO and Mrs. G. NAGAMANI for their selfless love, goodwill,

commendable sacrifice and colossal affection which has groomed me up to this level.

I sincerely thank my brother Mr. G. GANESH KUMAR and uncle

Mr. A.S.S. CHINNARAO for their encouragement and affection

I render my sincere thanks to all the TEACHING, NON-TEACHING STAFF

MEMBERS and my ALL FRIENDS Department of Chemistry, Annamalai University for

their kind help.

I thank one and all who have been associated with this work

Place : Annamalainagar (SHANMUKHA PRASAD GOPI)

Date :

CONTENTS

CHAPTER TITLE PAGE

LIST OF TABLES i-ii

LIST OF FIGURES iii-vi

LIST OF ABBREVIATIONS vii

1 INTRODUCTION

1.1 Water – Its significance and sources … 1

1.2 Treatment methods … 3

1.2.1 External treatment methods … 3

1.2.1.1 Coagulation and flocculation … 4

1.2.1.2 Filtration … 4

1.2.1.3 Ion Exchange … 5

1.2.1.4 Membrane filtration … 6

1.2.2 Internal treatment in boilers … 7

1.3 Crystal growth and morphology … 9

1.3.1 Polymorphism … 11

1.4 Calcium Carbonate (CaCO3) … 11

1.5 Summary of the literature … 21

1.6 Objective of the work … 21

1.7 Scope of the work … 22

2 MATERIALS AND METHODS

2.1 Materials and Reagents

2.1.1 Materials … 23

2.1.1.1

Ethylenediaminetetraacetic acid – Disodium salt (EDTA)

… 23

2.1.1.2

Nitrilotriacetic acid - Di sodium salt (NTA)

… 24

2.1.1.3

Diethylenetriaminepentaacetic acid (DTPA)

… 25

2.1.1.4

N-(hydroxyethyl)-ethylenediaminetriacetic acid (HEDTA)

… 26

2.1.1.5

Hydroxyethylidene-1,1-Diphosphonic acid (HEDP-AQ 330)

… 26

2.1.2 Reagents

2.1.2.1

Preparation of 0.1 M Calcium chloride (CaCl2) solution

…

27

CHAPTER TITLE PAGE

2.1.2.2

Preparation of 0.1 N Sodium Carbonate (Na2CO3) solution

… 28

2.1.2.3

Preparation of 0.1M Ethylenediaminetetraacetic acid (EDTA) disodium salt solution

… 28

2.1.2.4

Preparation of 0.1M Nitrilotriacetic acid (NTA) disodium salt solution

… 28

2.1.2.5

Preparation of 0.1M N-(hydroxyethyl)-ethylenediaminetriacetic acid (HEDTA) solution

… 28

2.1.2.6

Preparation of 0.1M Diethylenetriaminepentaacetic acid (DTPA) solution

… 28

2.1.2.7

Preparation of 0.1M 1-Hydroxyethylidene-1,1-Diphosphonic acid (HEDP (AQ 330)) solution

… 28

2.1.2.8

List of all chemicals and reagents used

… 29

2.2 Synthesis of samples

2.2.1 Synthesis below 100 °C … 29

2.2.2

Synthesis at 100 °C and above

… 29

2.3

Equipments used for synthesis of CaCO3

2.3.1 Rotamantle … 30

2.3.2 Programmable autoclave … 30

2.3.3 Hydro thermal autoclave … 31

2.4 Instruments used for characterization

2.4.1

Fourier Transform Infrared spectroscopy

… 31

2.4.2

Powder X-ray diffraction spectroscopy

… 31

2.4.3 Raman Spectroscopy … 32

2.4.4

Morphological studies using Scanning Electron Microscope

… 34

Transmission Electron … 34

CHAPTER TITLE PAGE

2.4.5 Microscopy (TEM) & Energy Dispersive X-Ray Spectroscopy (EDAX)

2.4.6 pH meter … 35

2.4.7 List of all equipments used … 35

RESULTS AND DISCUSSION

3 INTRODUCTION … 47

3.1

Synthesis of CaCO3 without any additive (blank)

… 48

3.1.1

Polymorphic identification by FTIR spectroscopy

… 48

3.1.2

Characterization and quantitative estimation using powder X-ray diffraction

… 49

3.1.3 Raman spectroscopy … 51

3.1.4 Morphological studies … 52

3.2

Synthesis of CaCO3 in the presence of EDTA

… 56

3.2.1


… 56

3.2.2


… 57



3.2.5 Mechanism … 67

3.3

Synthesis of CaCO3 in the presence of NTA

… 69

3.3.1


… 69

3.3.2


… 71



3.3.5 Mechanism 77

3.4

Synthesis of CaCO3 in the presence of HEDTA

… 80

3.4.1 Polymorphic identification by … 80

CHAPTER TITLE PAGE

FTIR spectroscopy

3.4.2


… 82



3.4.5 Mechanism 90

3.5

Synthesis of CaCO3 in the presence of DTPA

… 93

3.5.1


… 93

3.5.2


… 94




3.6

Synthesis of CaCO3 in the presence of HEDP(AQ-330)-20 ml

… 104

3.6.1


… 104

3.6.2. Characterization and quantitative estimation using powder X-ray diffraction

… 105



3.7

Synthesis of CaCO3 in the presence of HEDP(AQ-330)-10 ml

… 111

3.7.1


… 111

3.7.2


… 112




BLENDED SYSTEMS

3.8

Synthesis of CaCO3 in the presence of EDTA and HEDP

… 121

3.8.1 Polymorphic identification by … 121

CHAPTER TITLE PAGE

FTIR spectroscopy

3.8.2


… 123



3.8.5

Transmission Electron Microscope (TEM)

… 130

3.8.5.1

Selected-Area Electron Diffraction (SAED)

… 131


3.9

Synthesis of CaCO3 in the presence of EDTA and NTA

… 135

3.9.1


… 135

3.9.2


… 137



3.9.5 Mechanism 144

3.10

Synthesis of CaCO3 in the presence of HEDP and NTA

… 146

3.10.1


… 146

3.10.2


… 147



3.10.5 Mechanism 154

3.11

Synthesis of CaCO3 in the presence of EDTA and HEDTA

… 156

3.11.1


… 156

3.11.2


… 157



CHAPTER TITLE PAGE


3.12

Synthesis of CaCO3 in the presence of HEDP and HEDTA

… 167

3.12.1


… 167

3.12.2


…

168




3.13

Synthesis of CaCO3 in the presence of NTA and HEDTA

… 176

3.13.1


… 176

3.13.2


… 178




3.14

Synthesis of CaCO3 in the presence of HEDP and DTPA

… 186

3.14.1


… 186

3.14.2


… 187




3.15

Synthesis of CaCO3 in the presence of EDTA and DTPA

… 195

3.15.1


… 195

3.15.2


… 197


CHAPTER TITLE PAGE



3.16

Synthesis of CaCO3 in the presence of NTA and DTPA

… 206

3.16.1


… 206

3.16.2


… 207




3.17

Synthesis of CaCO3 in the presence of HEDTA and DTPA

… 216

3.17.1


… 216

3.17.2


… 217




4 CONCLUSION AND FUTURE SCOPE

4.1 Without any chelating agent (blank) … 225

4.2 Effect of individual chelating agents … 225

4.3 Effect of blended systems … 226

4.4 Optimization of system … 230

4.6 Future scope 238

5 REFERENCES … 239

APPENDICES 250

LIST OF PUBLICATIONS

i

LIST OF TABLES

Table

No. Captions

Page

No.

1.1 Crystalline scale constituents identified by X-ray diffraction 8

2.1 Details of the samples prepared 36

2.2 Raman band positions (wave numbers in cm−1) of calcite, aragonite and vaterite from literature and this study

33

3.1 Molar percentage of different polymorphs of CaCO3 present in blank samples

50

3.2 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of EDTA

59

3.3 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of NTA

72

3.4 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of HEDTA

83

3.5 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of DTPA

95

3.7 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of HEDP 10 ml

113

3.8 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of EDTA and HEDP blended system

124

3.9 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of EDTA and NTA blended system

138

3.10 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of HEDP and NTA blended system

148

3.11 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of EDTA and HEDTA blended system

158

3.12 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of HEDP and HEDTA blended system

169

3.13 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of NTA and HEDTA blended system

179

3.14 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of HEDP and DTPA blended system

188

ii

LIST OF TABLES

Table

No. Captions

Page

No.

3.15 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of EDTA and DTPA blended system

198

3.16 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of NTA and DTPA blended system

209

3.17 Molar percentage of different polymorphs of CaCO3 samples synthesised in the presence of HEDTA and DTPA blended system

218

iii

LIST OF FIGURES

Figure

No. Captions

Page

No.

1.1 Breakup of water resources on earth 2

3.1.1 FT-IR of CaCO3 (blank samples) 49

3.1.2 XRD patterns of CaCO3 (blank samples) 50

3.1.3 Raman spectra of CaCO3 (blank samples) 51

3.1.4 SEM images of CaCO3 blank samples 53-54

3.2.1 FT-IR of CaCO3 samples synthesized in the presence of EDTA

57

3.2.2 XRD patterns of CaCO3 samples synthesized in the presence of EDTA

58

3.2.3 Raman spectra of CaCO3 samples synthesized in the presence of EDTA

61

3.2.4 SEM images of CaCO3 samples synthesized in the presence of EDTA

64-65

3.3.1(a) FT-IR of CaCO3 samples synthesized in the presence of NTA

70

3.3.1(b) Deconvoluted FT-IR of CaCO3 samples synthesized in the presence of NTA

70

3.3.2 XRD patterns of CaCO3 samples synthesized in the presence of NTA

71

3.3.3 Raman spectra of CaCO3 samples synthesized in the presence of NTA

73

3.3.4 SEM images of CaCO3 samples synthesized in the presence of NTA

75-76

3.4.1(a) FT-IR of CaCO3 samples synthesized in the presence of HEDTA

80

3.4.1(b) Deconvoluted FT-IR of CaCO3 samples synthesized in the presence of HEDTA at 60 and 80 °C

81

3.4.2 XRD patterns of CaCO3 samples synthesized in the presence of HEDTA

82

3.4.3 Raman spectra of CaCO3 samples synthesized in the presence of HEDTA 84

3.4.4 SEM images of CaCO3 samples synthesized in the presence of HEDTA

86,87,89

3.5.1 FT-IR of CaCO3 samples synthesized in the presence of DTPA

93

3.5.2 XRD patterns of CaCO3 samples synthesized in the presence of DTPA

95

iv

Figure No.

Captions Page No.

3.5.3 Raman spectra of CaCO3 samples synthesized in the presence of DTPA

97

3.5.4 SEM images of CaCO3 samples synthesized in the presence of DTPA

99-100

3.6.1 FT-IR of CaCO3 samples synthesized in the presence of HEDP-20 ml

105

3.6.2 XRD patterns of CaCO3 samples synthesized in the presence of HEDP-20 ml

106

3.6.3 Raman spectra of CaCO3 samples synthesized in the presence of HEDP-20 ml

107

3.6.4 SEM images of CaCO3 samples synthesized in the presence of HEDP-20 ml

109-110

3.7.1 FT-IR of CaCO3 samples synthesized in the presence of HEDP-10 ml

112

3.7.2 XRD patterns of CaCO3 samples synthesized in the presence of HEDP-10 ml

113

3.7.3 Raman spectra of CaCO3 samples synthesized in the presence of HEDP-10 ml

115

3.7.4 SEM images of CaCO3 samples synthesized in the presence of HEDP-10 ml 117-118

3.8.1(a) FT-IR of CaCO3 samples synthesized in the presence of EDTA and HEDP blended system

122

3.8.1(b) Deconvoluted FT-IR of CaCO3 prepared in the presence of EDTA and HEDP blended system at 130 °C

122

3.8.2 XRD patterns of CaCO3 samples synthesized in the presence of EDTA and HEDP blended system

123

3.8.3 Raman spectra of CaCO3 samples synthesized in the presence of EDTA and HEDP blended system

125

3.8.4 SEM images of CaCO3 samples synthesized in the presence of EDTA and HEDP blended system

127-128

3.8.5 (a, b)

Magnified TEM image of rose-like vaterite 130

3.8.5 (c) EDAX spectrum of CaCO3 sample synthesized in the presence of EDTA and HEDP blended system at 230 °C

131

3.8.5.1 (a, b)

Selected area electron diffraction for hexagonal structure of vaterite phase taken along the (112) direction

132

3.8.5.1 (c)

Selected area electron diffraction for hexagonal structure of vaterite phase taken along the (111) direction

132

v

Figure No.

Captions Page No.

3.9.1 (a) FT-IR of CaCO3 samples synthesized in the presence of EDTA and NTA blended system

136

3.9.1 (b) Deconvoluted FT-IR of CaCO3 prepared in the presence of EDTA and NTA blended system at 130 °C

136

3.9.2 XRD patterns of CaCO3 samples synthesized in the presence of EDTA and NTA blended system

137

3.9.3 Raman spectra of CaCO3 samples synthesized in the presence of EDTA and NTA blended system

139

3.9.4 SEM images of CaCO3 samples synthesized in the presence of EDTA and NTA blended system

141-142

3.10.1 FT-IR of CaCO3 samples synthesized in the presence of HEDP and NTA blended system

146

3.10.2 XRD patterns of CaCO3 samples synthesized in the presence of HEDP and NTA blended system

148

3.10.3 Raman spectra of CaCO3 samples synthesized in the presence of HEDP and NTA blended system

150

3.10.4 SEM images of CaCO3 samples synthesized in the presence of HEDP and NTA blended system

151-152

3.11.1 FT-IR of CaCO3 samples synthesized in the presence of EDTA and HEDTA blended system

156

3.11.2 XRD patterns of CaCO3 samples synthesized in the presence of EDTA and HEDTA blended system

158

3.11.3 Raman spectra of CaCO3 samples synthesized in the presence of EDTA and HEDTA blended system

160

3.11.4 SEM images of CaCO3 samples synthesized in the presence of EDTA and HEDTA blended system

162-163

3.12.1 FT-IR of CaCO3 samples synthesized in the presence of HEDP and HEDTA blended system

167

3.12.2 XRD patterns of CaCO3 samples synthesized in the presence of HEDP and HEDTA blended system

169

3.12.3 Raman spectra of CaCO3 samples synthesized in the presence of HEDP and HEDTA blended system

170

3.12.4 SEM images of CaCO3 samples synthesized in the presence of HEDP and HEDTA blended system

172-173

3.13.1 FT-IR of CaCO3 samples synthesized in the presence of NTA and HEDTA blended system

177

3.13.2 XRD patterns of CaCO3 samples synthesized in the presence of NTA and HEDTA blended system

178

3.13.3 Raman spectra of CaCO3 samples synthesized in the presence of NTA and HEDTA blended system

180

vi

Figure No.

Captions Page No.

3.13.4 SEM images of CaCO3 samples synthesized in the presence of HEDP and DTPA blended system

182-183

3.14.1 FT-IR of CaCO3 samples synthesized in the presence of HEDP and DTPA blended system

187

3.14.2 XRD patterns of CaCO3 samples synthesized in the presence of HEDP and DTPA blended system

188

3.14.3 Raman spectra of CaCO3 samples synthesized in the presence of HEDP and DTPA blended system

190

3.14.4 SEM images of CaCO3 samples synthesized in the presence of HEDP and DTPA blended system

191-192

3.15.1 (a) FT-IR of CaCO3 samples synthesized in the presence of EDTA and DTPA blended system

196

3.15.1 (b) Deconvoluted FT-IR of CaCO3 prepared in the presence of EDTA and DTPA at 100 °C

196

3.15.2 XRD patterns of CaCO3 samples synthesized in the presence of EDTA and DTPA blended system

198

3.15.3 Raman spectra of CaCO3 samples synthesized in the presence of EDTA and DTPA blended system

200

3.15.4 SEM images of CaCO3 samples synthesized in the presence of EDTA and DTPA blended system

202-203

3.16.1 FT-IR of CaCO3 samples synthesized in the presence of NTA and DTPA blended system

207

3.16.2 XRD patterns of CaCO3 samples synthesized in the presence of NTA and DTPA blended system

208

3.16.3 Raman spectra of CaCO3 samples synthesized in the presence of NTA and DTPA blended system

210

3.16.4 SEM images of CaCO3 samples synthesized in the presence of NTA and DTPA blended system

212-213

3.17.1 FT-IR of CaCO3 samples synthesized in the presence of HEDTA and DTPA blended system

217

3.17.2 XRD patterns of CaCO3 samples synthesized in the presence of HEDTA and DTPA blended system

218

3.17.3 Raman spectra of CaCO3 samples synthesized in the presence of HEDTA and DTPA blended system

220

3.17.4 SEM images of CaCO3 samples synthesized in the presence of HEDTA and DTPA blended system

221-222

vii

LIST OF ABBREVIATIONS

µm – Micrometre

Å – Angstroms

ACC – Amorphous Calcium Carbonate1

AR – Analytical reagent

CaCO3 – Calcium Carbonate

cm – Centimeter

DTPA – Diethylenetriaminepentaacetic acid

EDAX – Energy dispersive X-ray spectroscopy

EDTA – Ethylenediaminetetraacetic acid

FE-SEM – Field emission scanning electron microscopy

FT-IR – Fourier transform infrared spectroscopy

h – Hour

HEDP – Hydroxyethylidene-1,1-Diphosphonic acid

HEDTA – N-(Hydroxyethyl)-ethylenediaminetriacetic acid

JCPDS - Joint committee for powder diffraction standards

M – Molar (or) Molarity

mg – Milligram

mL – Milliliter

nm – Nanometer

NTA – Nitrilotriacetic acid

SEM – Scanning electron microscopy

TEM – Transmission electron microscopy

Temp – Temperature

XRD – X-Ray diffraction

ABSTRACT

CaCO3 is one of the most predominant components of hard and

tenacious scale found in boiler tubes and in heat exchangers. It exhibits

three crystalline polymorphs (stable calcite, meta-stable aragonite, and

vaterite) and two hydrated polymorphs (monoclinic hexahydrate (ikaite)

and CaCO3 monohydrate). It also exists in amorphous forms. Since

different polymorphic forms of same substance have different properties,

polymorphism plays an important role in controlling the scale formation.

For example, the predominant polymorphic form of calcium carbonate in

scale is calcite and vaterite is seldom present. However, one of the long-

standing challenges is the ability to predict and control polymorphism.

Although calcite is most stable polymorph of CaCO3, less stable

aragonite and vaterite may be stabilized under certain

temperatures/conditions in the presence of some additives/inhibitors. In

order to understand the process of building up of the scale from an

atomistic level and its preclusion, it is essential to study the formation of

each constituent in the scale independently and then synergistically, in

the presence of different scale inhibitors under different conditions. To

understand this phenomenon we have used five different chelating

agents viz. Ethylenediaminetetraacetic acid (disodium salt), 1-

Hydroxyethylidene-1,1-Diphosphonic acid (Aquasoft-330), Nitrilotriacetic

acid (disodium salt, N-(hydroxyethyl)-ethylenediaminetriacetic acid, and

Diethylenetriaminepentaacetic acid were employed in this study and

experiments were carried out between 60 and 230 °C.

BREIF DETAILS AND ORGANIZATION OF THESIS CHAPTERS

Chapter 1 gives a brief introduction of sources of water, its uses,

treatment methods and literature survey on effect of different additives

on the polymorphism of CaCO3.

Chapter 2 describes the Materials and experimental techniques

used in the investigation.

Chapter 3 deals with the interpretation of FTIR, XRD, RAMAN and

Morphological studies (SEM) and mechanism on the observations made.

This chapter is divided into 17 sections (3.1 to 3.17), each section deals

with the effect of an individual additives or a combination of additives

(blended systems).

The details of conclusions drawn from the studies and most

favorable systems for preclusion of CaCO3 scale (based on

calcite/vaterite composition in the scale) at various temperatures under

the study are discussed in Chapter 4 followed by references, appendix

and publications.

A STUDY ON THE POLYMORPHISM AND MORPHOGENESIS OF...

Documents

Transcript of A STUDY ON THE POLYMORPHISM AND MORPHOGENESIS OF...