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Quantification of Hafnium in Selected Inorganic and Organometallic Compounds

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Quantification of Hafnium in Selected Inorganic and Organometallic Compounds Quantification of hafnium in selected inorganic and organometallic compounds A dissertation submitted to meet the requirements for the degree of Magister Scientiae in the FACULTY OF NATURAL AND AGRICULTURAL SCIENCES DEPARTMENT OF CHEMISTRY at the UNIVERSITY OF THE FREE STATE BLOEMFONTEIN by GONTSE ATLHOLANG ADELINE MALEFO Supervisor Prof. W. Purcell Co-supervisors Dr. J.T. Nel and Dr. M Nete February 2016 Declaration I declare that the thesis entitled “THE QUANTIFICATION OF HAFNIUM IN SELECTED INORGANIC AND ORGANOMETALLIC COMPOUNDS” submitted for the degree Magister in Analytical Chemistry, at the University of the Free State is my own original work and has not been previously submitted to any other institution of higher education in the Republic of South Africa or abroad. I further declare that all sources cited or quoted are indicated and acknowledged by means of a comprehensive list of references. Signature………………………………… Date…………………..…………. Gontse Atlholang Adeline Malefo Acknowledgements I would like to thank and express my sincere gratitude to; My Lord and saviour, Jesus Christ for his grace, divine guidance and all the strength bestowed upon me throughout the research project. My supervisor, Prof. W. Purcell for his guidance and patient support throughout the research project. His expertise and understanding contributed greatly to my knowledge in the field of study. My co-supervisor, Dr. Nel, for his valuable contributions in assisting with reviews of each chapter which greatly improved/enhanced the content my thesis. My co-supervisor, Dr. M. Nete, for his continuous encouragement and support. He was very helpful to the completion of this study. Analytical chemistry group (Deidre, Dika, Hlengiwe, Enerstine, Melaku, Ntoi, Sibongile, Sumit, Trevor and Qinisile) for providing a conducive work environment. Necsa and the New Metal Development Network of the Advanced Metals Initiative of the Department of Science and Technology of South Africa for financial support. My family and friends (Gaopalelwe, Molly, Ngamola, Semi, Sifa, Dineo, Puleng, Keaorata, Khumo, Palesa, Pheello, Mbodi Muthambi, Thabo, Tshepi and Michell) for their motivation, love and support throughout my study. Gontse Malefo TABLE OF CONTENTS LIST OF FIGURES ....................................................................................................... V LIST OF TABLES ..................................................................................................... VIII LIST OF ABBREVIATION ...................................................................................... XII KEY WORDS............................................................................................................. XIV CHAPTER 1 – MOTIVATION OF THE STUDY ...................................................... 1 1.1. BACKGROUND ........................................................................................................................... 1 1.2. THE IMPORTANCE OF HAFNIUM ........................................................................................... 3 1.3. AIM OF THE STUDY .................................................................................................................. 6 CHAPTER 2 – OVERVIEW OF HAFNIUM .............................................................. 7 2.1. INTRODUCTION ...................................................................................................................... 7 2.2. HAFNIUM MARKET OVERVIEW.......................................................................................... 8 2.3. THE EXTRACTION OF HAFNIUM FROM MINERAL ORES ............................................. 14 2.3.1. CARBOCHLORINATION EXTRACTION ............................................................... 17 2.3.2. ALKALI EXTRACTION ............................................................................................ 18 2.3.2.1. CAUSTIC FUSION .................................................................................... 18 2.3.2.2. SODA FUSION .......................................................................................... 18 2.4. SEPARATION OF ZIRCONIUM AND HAFNIUM ............................................................. 19 2.4.1. EXTRACTIVE DISTILLATION ............................................................................... 19 2.4.2. LIQUID – LIQUID EXTRACTION ........................................................................... 20 2.5. HAFNIUM PRODUCTION ................................................................................................... 22 2.5.1. CHLORINATION AND KROLL REDUCTION ....................................................... 22 2.6. CHEMISTRY OF HAFNIUM ............................................................................................... 26 2.6.1. PHYSICAL PROPERTIES ......................................................................................... 26 2.6.2. CHEMICAL PROPERTIES........................................................................................ 27 2.7. COMPOUNDS OF HAFNIUM ............................................................................................. 30 2.7.1. HAFNIUM OXIDE ..................................................................................................... 30 2.7.2. HAFNIUM CARBIDE ................................................................................................ 31 2.7.3. HAFNIUM HALIDES ................................................................................................ 32 2.8. APPLICATION AND USES OF HAFNIUM ........................................................................ 34 2.9. CONCLUSION ...................................................................................................................... 36 CHAPTER 3 – DISSOLUTION AND QUANTIFICATION TECHNIQUES USED FOR HAFNIUM CONTAINING COMPOUNDS (LITERATURE REVIEW) ..... 37 3.1. INTRODUCTION .................................................................................................................. 37 3.2. METHODS OF DIGESTION ................................................................................................. 38 3.2.1. OPEN VESSEL ACID DIGESTION .................................................................... 38 3.2.2. DIGESTION BY FUSION .................................................................................... 39 3.2.3. MICROWAVE ACID ASSISTED DIGESTION SYSTEM ................................. 43 3.2.4. DISSOLUTION OF HAFNIUM OXIDE BY RADIOACTIVE TRACER TECHNIQUE ........................................................................................................ 46 3.3. QUANTIFICATION OF HAFNIUM IN DIFFERENT CHEMICAL COMPOUNDS .......... 48 3.3.1. DETERMINATION OF ZR/HF IN DIFFERENT SAMPLES USING ICP-OES AND ICP-MS ........................................................................................................ 48 3.3.2. DETERMINATION OF HF IN DIFFERENT SAMPLES USING XRF AND NAA TECHNIQUES............................................................................................. 53 3.3.3. GRAVIMETRIC DETERMINATION OF HAFNIUM ........................................ 57 3.4. SYNTHESIS AND CHARACTERIZATION OF HAFNIUM COMPLEXES ...................... 62 3.4.1. INFRARED SPECTROSCOPY ............................................................................ 62 3.4.2. X-RAY CRYSTALLOGRAPHY .......................................................................... 66 3.4.3. CHNS – ELEMENTAL ANALYSIS .................................................................... 68 3.5. CONCLUSION ...................................................................................................................... 70 CHAPTER 4 – DISSOLUTION AND ANALYTICAL TECHNIQUES ................. 71 4.1. INTRODUCTION .................................................................................................................. 71 4.2. DIGESTION TECHNIQUES ................................................................................................. 72 4.2.1. OPEN VESSEL DIGESTION .................................................................................. 72 4.2.2. FLUX FUSION ........................................................................................................ 73 4.2.3. MICROWAVE ACID – ASSISTED DIGESTION SYSTEM ................................. 76 4.3. ICP-OES ANALYTICAL TECHNIQUE ............................................................................... 80 4.4. SYNTHESIS AND CHARACTERIZATION OF HAFNIUM COMPLEXES ...................... 85 4.5. X-RAY CRYSTALLOGRAPHY ........................................................................................... 88 4.6. CHNS – ELEMENTAL ANALYSIS ..................................................................................... 90 4.7. CONCLUSION ...................................................................................................................... 92 CHAPTER 5 – METHOD DEVELOPMENT FOR THE DIGESTION AND QUANTIFICATION OF HAFNIUM CONTAINING COMPOUNDS ................... 93 5.1. INTRODUCTION .................................................................................................................. 93 5.2. GENERAL EXPERIMENTAL PROCEDURES ................................................................... 94 5.2.1. EQUIPMENT AND REAGENTS ............................................................................ 94 5.2.2. GENERAL EQUIPMENT ....................................................................................... 96 ii 5.2.2.1. WEIGHING ............................................................................................
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