Luận án PhD: Hình thành tiền chất apatite và vai trò cô lập kim loại nặng, phóng xạ

MIAMI UNIVERSITY The Graduate School Certificate for Approving the Dissertation We herby approve the Dissertation of Olaf J. Borkiewcz Candidate for the Degree: Doctor of Philosophy _____________________________________________________________________________ Dr. John Rakovan, Director _____________________________________________________________________________ Dr. Cahill, Reader _____________________________________________________________________________ Dr.

Hailiang Dong, Reader _____________________________________________________________________________ Dr. Hughes, Reader _____________________________________________________________________________ Dr. Jason Rech, Reader _____________________________________________________________________________ Dr. Andre Sommer, Graduate School Representative ABSTRACT FORMATION OF PRECURSOR CALCIUM PHOSPHATE PHASES DURING CRYSTAL GROWTH OF APATITE AND THEIR ROLE ON THE SEQUESTRATION OF HEAVY METALS AND RADIONUCLIDES by Olaf J.

Borkiewicz Due to increasing risk associated with the contamination of the environment with heavy metals and radionuclides, societies worldwide are facing a pressing need for new more efficient environmental remediation techniques. One approach that gained considerable attention over the last two decades is in situ metal stabilization by phosphate amendments – a technique based on the coprecipitation of contaminant species with phosphates and the formation of insoluble metal(M)-substituted minerals, such as apatite Ca5-xMx(PO4)6(OH,Cl,F). One of the major results of this dissertation is that formation of apatite at Earth-surface conditions is preceded by crystallization of other less stable calcium phosphates (precursors) that ultimately transform to apatite. The first part of this dissertation investigates formation and evolution of calcium phosphate precursors under conditions simulating those found in Earth-surface environments.

The pathways of phase development in the Ca(OH)2-H3PO4-H2O system were studied using conventional ex situ as well as in situ time-resolved X-ray diffraction. The results clearly indicate formation of precursors under conditions found at the Earth-surface, which may be relevant not only in the context of natural soil environments, but also in the context of engineered conditions, like those found during metal stabilization by phosphate amendments. In the second part of the dissertation, pathways of calcium phosphate development in the presence of different metal ions (Zn, Cd, Sr, U, and Th) are studied by time-resolved X-ray diffraction. The results clearly indicate a significant influence of contaminant species on the pathways of phase development in the Ca(OH)2-H3PO4-H2O system.

Secondary metal-bearing phases, far more soluble than hydroxylapatite, were often formed in the presence of the metals studied. Finally, the role of precursor formation on the heavy metal sequestration and fate during crystal growth of apatite was studied by a combination of powder X-ray diffraction, SEM/EDS and ICP-AES. The results indicate significant reduction in the solution concentration of metals during formation of precursor phases and relative stability of the contaminant species during structural transformation of phases involved in low-temperature crystallization of hydroxylapatite. Fluctuations in the concentration of elements observed during structural changes in the system suggest a dissolution-recrystallization mechanism of transformation of amorphous phases to brushite and parascholzite.

FORMATION OF PRECURSOR CALCIUM PHOSPHATE PHASES DURING CRYSTAL GROWTH OF APATITE AND THEIR ROLE ON THE UPTAKE OF HEAVY METALS AND RADIONUCLIDES A DISSERTATION Submitted to the Faculty of Miami University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Department of Geology by Olaf Borkiewicz Miami University Oxford, Ohio 2010 Dissertation Director: John Rakovan, Ph. TABLE OF CONTENTS Chapter 1: Introduction 1 References 5 Chapter 2: Time-resolved in situ studies of apatite formation pathways in aqueous solutions 10 Abstract 11 Body Text 12 References 33 Tables and Figures 42 Chapter 3: Impact of metal ions on hydroxylapatite formation pathways in aqueous solutions – time resolved in situ studies 55 Abstract 56 Body Text 57 References 78 Tables and Figures 86 Chapter 4: The role of precursors formation on the sequestration and fate of metals during hydroxylapatite crystallization 99 Abstract 100 ii Body Text 101 References 118 Tables and Figures 119 Chapter 5: Concluding remarks and suggestion for future work 141 iii LIST OF TABLES Chapter 2: Time-resolved in situ studies of apatite formation pathways in aqueous solutions 10 1 – Experimental details of ex situ X-ray diffraction investigation. ACP – amorphous calcium phosphate, B – brushite, HAP – hydroxylapatite 42 2 – Experimental details of in situ X-ray diffraction investigations carried out at pH=6. ACP – amorphous calcium phosphate, B – brushite, HAP – hydroxylapatite, M – monetite 43 3 - Experimental details of in situ X-ray diffraction investigations carried out at pH = 9.

ACP – amorphous calcium phosphate, HAP – hydroxylapatite 44 Chapter 3: Impact of metal ions on hydroxylapatite formation pathways in aqueous solutions – time resolved in situ studies 55 1 – Summary of the experimental details of in situ X-ray investigations in the presence of Cd, Sr, and Zn 87 2 – Summary of the experimental details of in situ X-ray investigations in the presence of U and Th 88 Chapter 4: The role of precursors formation on the sequestration and fate of metals during hydroxylapatite crystallization 99 1 – Experimental details of the experiments carried out at near-neutral pH 119 2 – Experimental details of the experiments carried out at alkaline pH 120 iv LIST OF FIGURES Chapter 2: Time-resolved in situ studies of apatite formation pathways in aqueous solutions 10 1 – Calculated solubility isotherms of calcium phosphate phases in the system Ca(OH)2-H3PO4- H2O at 37°C. Phases present on the diagram: hydroxylapatite, OHAp [Ca10(PO4)6(OH)2]; tricalcium, TCP phosphate [Ca3(PO4)2]; octacalcium phosphate, OCP [Ca4H(PO4)3]; dicalcium phosphate anhydrous, DCPA (monetite) CaHPO4; and dicalcium phosphate dihydrate, DCPD (brushite)[ CaHPO4 • 2H2O]. From Elliot, 1994 46 2 – Diffraction patterns obtained during low pH ex situ experiment ES-1. Bottom pattern represents the initial precipitate, upper the final product of the reaction; B – brushite, H – hydroxylapatite 47 3 - Scanning electron micrographs of the products of ex situ experiments.

A – amorphous calcium phosphate, B – brushite, C and D – hydroxylapatite 48 4 – Final observed (crosses), calculated (solid line), and difference (lower) patterns for Rietveld refinement of samples from three different experiments; A – 55-min mark of IS-02, sample containing OCP, brushite and hydroxylapatite; B – 55-min mark of IS-03, sample containing brushite and hydroxylapatite; C – 55-min mark of IS-04, sample containing monetite and hydroxylapatite 49 5 – Phase evolution with time for IS-02 (a), IS-03(b) and IS-04 (c) 50 6 – Time-resolved plot of the experiment IS-1. Near-neutral pH at 25°C temperature. All peaks present in the diffractogram correspond to PDF™ 09-0077 brushite 51 7 – Time-resolved plot of the experiment IS-2 showing phase evolution in the system at 45°C; B – brushite, M – monetite 52 8 – Electron microphotograph of typical final products of in situ experiments at near-neutral (A) and high pH (B) 53 v 9 – Diffraction patterns obtained during high-pH in situ experiment IS-4. The Y-axis represents intensity and relative non-linear time scale.

H – hydroxylapatite 54 Chapter 3: Impact of metal ions on hydroxylapatite formation pathways in aqueous solutions – time resolved in situ studies 55 1 – Experimental setup during in situ diffraction experiments 89 2 – Phase evolution with time for the experiments carried out in the presence of cadmium 90 3 – Electron microphotograph of the typical final products of experiments at near-neutral pH, at 10 wt% (a) and at 20 wt% Cd (b) 91 4 – Diffractogram representing composition of the final product of the IS-Sr-30. SrAp – strontium hydroxylapatite; Sr-P – Sr0.1(PO4)2 92 5 – Electron microphotograph of the typical final products of experiments at near-neutral pH, at 10 wt% (a) and 20 wt% Sr (b) 93 6 – Diffractogram representing sample composition in the final stages of experiment IS-2. HAP – hydroxylapatite, PS – parascholzite 94 7 – Phase evolution with time for the experiments IS-Zn-20 (a) and IS-Zn-30 (b). 95 8 – Electron microphotograph of the typical final products of experiments at near-neutral pH in the presence of zinc 96 9 – Diffractogram representing composition of the final product of the IS-U-05.

M – monetite, C – chernikovite 97 10 - Electron microphotograph of the typical final products of experiments at near-neutral pH carried out in the presence of uranium (a) and thorium (b) 98 vi Chapter 4: The role of precursors formation on the sequestration and fate of metals during hydroxylapatite crystallization 99 1 – Diffraction patterns obtained during the ES-Zn-5 experiment. The Y-axis represents intensity and relative non-linear time scale. B – brushite, PS – parascholzite 123 2 – Evolution of solution concentration for Ca (a), P(b), Zn(c) and pH(d) during the experiments conducted in the presence of 5 and 10 wt% zinc at pH = 6 124 3 – Electron microphotograph of typical products of experiments carried out in the presence of zinc at pH = 6. Large crystals were identified as brushite; smaller crystals as parascholzite 125 4 – Diffraction patterns obtained during the ES-Zn-10 experiment.

The Y-axis represents intensity and relative non-linear time scale. B – brushite, PS – parascholzite 126 5 – Diffraction patterns obtained during the ES-Cd-5 experiment. The Y-axis represents intensity and relative non-linear time scale. B – brushite, OCP – octacalcium phosphate, HAP – hydroxylapatite 127 6 – Evolution of solution concentration for Ca (a), P(b), Cd(c) and pH(d) during the experiments conducted in the presence of 5 and 10 wt% cadmium at pH = 6 128 7 – Electron microphotograph of typical products of experiments carried out in the presence of 10 wt% cadmium at pH = 6 129 8 – Evolution of solution concentration for Ca (a), P(b), Sr(c) and pH(d) during the experiments conducted in the presence of 5 and 10 wt% strontium at pH = 6 130 9 – Electron microphotograph of typical products of experiments carried out in the presence of 10 wt% strontium at pH = 6 131 10 – Evolution of solution concentration for Ca (a), P(b), U(c) and pH(d) during the experiments conducted in the presence of 1 and 2 wt% uranium at pH = 6 132 11 – Electron microphotograph of typical products of experiments carried in the presence of uranium containing crystals of chernikovite (a) and in the presence of thorium containing crystals of ThO2 (b) 133 vii 12 – Diffraction patterns obtained during the ES-Sr-5_9.

The Y-axis represents intensity and relative non-linear time scale. HAP – hydroxylapatite 134 13 – Diffraction patterns obtained during the ES-U-2_9. The Y-axis represents intensity and relative non-linear time scale. HAP – hydroxylapatite, CH – chernikovite 135 14 – Evolution of solution concentration for Ca (a), P(b), Zn(c) and pH(d) during the experiments conducted in the presence of 5 and 10 wt% zinc at pH = 9 136 15 – Evolution of solution concentration for Ca (a), P(b), Cd(c) and pH(d) during the experiments conducted in the presence of 5 and 10 wt% zinc at pH = 9 137 16 – Evolution of solution concentration for Ca (a), P(b), Sr(c) and pH(d) during the experiments conducted in the presence of 5 and 10 wt% zinc at pH = 9 138 17 – Evolution of solution concentration for Ca (a), P(b), U(c) and pH(d) during the experiments conducted in the presence of 1 and 2 wt% zinc at pH = 9 139 18 – Evolution of solution concentration for Ca (a), P(b) and pH(c) during the experiments conducted in the presence of 1 and 2 wt% thorium at pH = 9.

Thorium concentration below detection limit throughout the experiments 140 viii Dedicated to my loving mom Maria Borkiewicz. Thank you for everything! ix ACKNOWLEDGMENTS A warm thank you goes to everyone who contributed to my work or helped me in any capacity over the last six years here at Miami University. Completion of this dissertation would not be possible without help, support and encouragement of many, many people from the Miami community and beyond. First and foremost my deepest and heartfelt gratitude goes towards my academic advisor Dr.

John Rakovan, whose wisdom, extraordinary patience and excellent guidance helped me not only to become a better scientist but also guided me through my new life paths here in the United States. Thank you, John, for all your help and tireless support. Along with John, Dr. Cahill from the George Washington University has played a critical role in this work and my life.