Arsenate substitution in synthetic hydroxylapatite – structural characterization of the Ca5 (PO4 ) x (AsO4 )3-x OH solid solution

Hydroxylapatite Ca5(PO4)3OH (HAP) and johnbaumite Ca5(AsO4)3OH (AsHAP) are isostructural apatite minerals naturally occurring in the oxidation zones. The main objective of this research is identification of systematic relation between structural and spectral properties and As content in the series

Synthesis and mineralogical characteristics of hydroxylapatite-hydroxylpyromorphite solid solution series Ca5(PO4)3OH – Pb5(PO4)3OH

Lead is a widespread environmental contaminant toxic to living organisms. Soils and wastes contaminated with Pb are found in both rural and urban settings. Uptake of Pb from waste, soil or water by phosphate compounds, particularly hydroxylapatite, has been proved as effective remediation strategy (Xu and Schwartz, 1994). The technology arises from the low solubility of lead apatites and from their rapid precipitation reactions. The structure of apatites can be described by the general formula A5(BO4)3C, where A: Ca, Pb, Sr, Ba; B: P, As, V; C: Cl, OH, F, Br, I. Apatites are very tolerant to structural distortion resulting from chemical substitution in cationic and anionic positions and consequently they are remarkably diverse in composition. The hydroxylapatite’s structure also allows for extended substitutions of cations and anions. It is hypothesized here that, thanks to the potential for extensive solid solutions in the system, the lead apatites precipitating in the environment are not pure end members but rather Pb-Ca solid solutions. A complete solid solution between hydroxylapatite (HAP) and hydroxylpyromorphite (HPY) was determined before (Bigi et al., 1991; Hadrich et al., 2001). The results, however, are still fragmentary and partly inconsistent. The objective of the project is systematic characterization (crystal structure as well as infrared and Raman vibrtational properties) of synthetic analogs of the minerals from HAP – HPY solid solution series. This will allow to clarify the controversies. Well characterized products of the synthesis will be used in future in thermodynamic study of solubility changes with substitution, which was never determined before. It is assumed that the properties vary in systematic way with Pb substitution for Ca. An effective wet method of synthesis of Ca-Pb apatites was developed. A crystalline, homogeneous precipitates with stoichiometric composition were produced. Six phases of HAP-HPY solid solution series were prepared by dropwise mixing of a solution containing calcium and/or lead ions and a phosphate solution at room temperature. During the synthesis pH of 8,5 was maintained using NH4OH. Precipitates were washed, air dried and characterized by scanning electron microscopy (SEM/EDS), powder X-ray diffraction,  infrared spectroscopy (FTIR) and Raman spectroscopy. All synthetic products obtained in the experiments form hexagonal needles less than 0.1 µm long. Elemental composition is consistent with theoretical stoichiometry of the phases. X-ray diffraction patterns reveal a shift toward lower angles 2θ for phases with higher lead contents. This indicates an enlargement of the lattice constants. The variation of parameters, however, is not linear (does not follow the Vegard’s law). Particularly the cell parameter c changes more for phases reach in lead. These results are in agreement with those reported previously (Bigi et al., 1991; Hadrich et al., 2001). A shift of band position is also observed in both FTIR and Raman spectra. All the bands shift towards lower wavenumber with increasing Pb content. In most cases the shift is not linear exhibiting two trends similar to lattice parameters. This may indicate that the vibrational properties of the phases in the series depend stronger on the bond length than on the atomic mass of substituting elements. This work was supported by AGH-UST statutory grant No. 11.11.140.319

CO2-brine-rock interactions as a result of long term experiment onto rock samples from Chabowo anticline, Poland

The presented work concerns investigations of CO2 -brine-rock interactions conducted over a period of 20-months. Experiments were carried out at laboratory scale with the use of equipment specifically designed for this purpose. Research materials (reservoir and cap rocks) were taken from the Chabowo 3 well located within Chabowo anticline. The experiments were carried out at room temperature (about 25ºC) and pressure about 6 MPa. For samples before and after the experiment a numerous investigations were carried out i.e. petrophysical (porosity, surface area, threshold diameter, average capillary, framework and bulk densities) and petrological-mineralogical characteristics. Also brine used for examination before and after experiment was analyzed (chemical analysis). Petrophysical results have shown a significant decrease of porosity (from 17.0% to 7.5%) and surface area (from 0.395 m2 /g to 0.196 m2 /g) in case of sandstone. These changes are caused probably by crystallization of halite in pore spaces, because mineralogical analysis (XRD) has shown the presence of halite (3–5% vol. in the rock) after experiment. More detailed results were obtained during mineralogical analyses of thin sections. These results have shown in sandstone samples a small increase of porosity and a small decrease of feldspar and cements (carbonate and clay) as well as matrix which suggests dissolution of these constituents. For claystone – after experiment XRD clay fraction has shown absence of clay minerals such as montmorillonite, which may also be caused by interaction between the rock, CO2 and brine. Dissolution of some minerals is evidenced by chemical analysis of brine where amounts of most tested ions increase after experiment for both sandstone and claystone

The effect of gluconic acid secretion by phosphate-solubilizing Pseudomonas putida bacteria on dissolution of pyromorphite Pb_{5}(PO_{4})_{3}Cl and Pb remobilization

The purpose of this study was to investigate the effect of bacterially produced gluconic acid on the dissolution of pyromorphite and Pb remobilization. Pyromorphite Pb_5(PO_4)_3Cl is formed as a product of the phosphate-induced treatment of Pb-contaminated sites. This very stable mineral greatly decreases the bioavailability of Pb. In this study, bacterial and abiotic batch experiments on the dissolution of pyromorphite were carried out. In the microbial experiments, the mineral was dissolved in the presence of the phosphate solubilizing soil bacterium, Pseudomonas putida. The bacterial growth medium was supplemented with glucose, which under natural conditions can be supplied to microbes via symbiosis with plants. P. putida acquired P from pyromorphite and enhanced its dissolution. Elevated Pb concentrations were observed in the suspensions with bacteria. The bacterial secretion of 16.5 mM gluconic acid played a significant role in Pb remobilization; the pH of the solution dropped down from an initial 7.4 to 3.5. In the abiotic experiments, pyromorphite was dissolved at several concentrations of gluconic acid and at an acidic to neutral pH range. Both acidification and formation of stable Ph-gluconate ligands enhanced the dissolution of pyromorphite and caused Pb remobilization

Pb remobilization by bacterially mediated dissolution of pyromorphite Pb_{5}(PO_{4})_{3}Cl in presence of phosphate-solubilizing Pseudomonas putida

Remediation of lead (Pb)-contaminated sites with phosphate amendments is one of the best studied and cost-effective methods for in situ immobilization. In this treatment, a very stable mineral, pyromorphite Pb(5)(PO(4))(3)Cl, is formed. Several studies propose to improve this treatment method with the addition of phosphate-solubilizing bacteria (PSB). The effect of bacteria on solubilization of pyromorphite is unknown. In this study, the effect of the soil microorganisms on the stability of pyromorphite Pb(5)(PO(4))(3)Cl has been investigated in a set of batch solution experiments. The mineral was reacted with Pseudomonas putida, a common soil microorganism. Dissolution of pyromorphite was enhanced by the presence of P. putida, resulting in an elevated Pb concentration in the solution. This occurred even when the bacteria were provided with an additional source of phosphate in the solution. Pyromorphite has been shown to be a potential source of nutrient phosphorus for common soil bacteria. Thus, the use of PSB in remediation treatments of Pb contaminated sites may have adverse long-term impacts on Pb immobilization. Conscious phosphate management is suggested for long-term sustainability of the in situ Pb immobilization by pyromorphite formation

Baklia Fault Zone – a regional strike slip zone splitting Prins Karls Foreland (Svalbard)

Prins Karls Foreland (PKF) is a westernmost island of Svalbard Archipelago belonging to the Southwestern Basement Province. The island consists of low-metamorphic facies metasediments, probably Neoproterozoic, divided into two parts, northern and southern. Both parts are characterized by similar geological structures but different stratigraphy. New discoveries presented here result from joint, Norwegian Polar Institute and AGH-Kraków expeditions in 2013 and 2014. For the first time thorough characteristics of the location and character of a strike-slip fault splitting PKF (the Baklia Fault Zone) is presented here.To date, one succession has been distinguished in the litostratigraphy of PKF’s basement. The northern part of the island consist of two groups: the Scotiafjellet Group and Grampianfjella Group (Dallmann et al. 2015). They comprise low-metamorphic metasediments (chlorite zone of greenschist facies), mostly slates, metapsamites and carbonates. Stratigraphic units of the southern part represent slightly higher, biotite metamorphic zone, and have been considered conformably underlying Scotiafjellet Group. The uppermost Peachflya Group and Geikiebreen Group (mostly phyllites with metavolcanics and carbonates) are in thrust contact with underlying Ferrierpiggen Group, comprising schistose diamictites (Harland et al. 1979, Harland et al. 1993).This complexes have undergone the Caledonian metamorphism followed by D1 deformation producing SE directed folding and thrusts. D2 deformation was coaxial, but not coplanar with D1. D2 deformation occurred probably in Mid-Kenozoic and resulted in refolding and thrusting, followed by dextral shearing in the central area of the island. D3 deformation is connected with transtensional formation of the Forlandsundet Graben along NNW-SSE faults finishing the West Spitsbergen Orogeny (WSO) (Manby 1986).Distinct difference in the stratigraphy of southern and northern parts of PKF is apparent. The presence of the fault dividing the island was indicated before (Hjelle et al. 1979), but no single fault has been recognized during detailed mapping later on (Harland et al. 1979; Morris 1982; Manby 1986; Morris 1989).Fieldwork conducted by the authors in the area of Selvågen led to the discovery of the a major fault zone (the Baklia Fault Zone - BFZ) dividing PKF into two terrains. The BKF have N-S trend from Haukebukta in the west coast, through the slopes of Alasdairhorne (where it trapped a few hundred meter long slab of the Ferrierpiggen Group rocks), to the southern Scotiadalen. Approaching Selvågen, the fault zone bends slightly to the NNE-SSW. The zone is filled with breccias and mixture of different lithologies with slabs of rocks derived from both limbs of the fault zone. The width of the zone measures approximately 100 to 250 meters. To the east, it is accompanied by at least three narrow subparallel faults. The age of the BFZ is unknown. A brittle character of deformation may suggest that it is of Tertiary age. En échelon normal faults with a drop to the north which associate BFZ may be considered as a Riedel shears R1 formed at the beginning of a strike-slip movement. Structural measurements on slickensides as kinematic indicators revealed that normal faulting was associated with both, dextral and sinistral shear (not simultaneous). A main movement connected with dextral shearing occurred probably earlier, during late stages of the early Tertiary crustal shortening. The extended width of the fault zone and the presence of a mixture of rock material from both terranes suggest the significant lateral displacement that might reach tens of kilometers. The BFZ cuts through the boundary faults of the Forlandsundet Graben displacing them sinistrally by approximately one kilometer. This suggests that sinistral movement was probably associated with rejuvenation of the fault during late stages or after the Forlandsundet Graben formation.There are several regional implications of BFZ. The stratigraphic relationship of southern and northern teranes is unclear. The presence of BFZ at the boundary of the Scotiafjellet and Peachflya Group does not exclude their stratigraphic succession but makes it impossible to define. The field observations suggest that BFY may be Tertiary of age. It has similar tectonic style and orientation to other strike slip zones present along western Svalbard coast. Strong tectonic deformation suggests displacement of the northern terrain of PKF by tens of kilometers. Even though southern terrain can be directly correlated with Oscar II Land, more research is needed to correlate of more exotic northern terrain of PKF with the basement rocks in the southern parts of Spitsbergen. Ongoing research towards dating and detail structural characterization of this regional fault zone will allow for reconstruction of pre-Tertiary position of this part of Archipelago. References Dallmann W.K., 2015 (Ed.): Geoscience Atlas of Svalbard. (Norwegian Polar Institute, Report 148) Tromsø.Harland, W. B., Horsfield, W. T., Manby, G. M., & Morris, A. P., 1979. An outline pre-Carboniferous stratigraphy of central western Spitsbergen. Norsk Polarinstitutt Skrifter, 167, 119-144.Harland, W. B., Hambrey, M. J., & Waddams, P., 1993. Vendian geology of Svalbard.Hjelle, A., Ohta, Y., & Winsnes, T. S., 1979. Hecla Hoek rocks of Oscar II Land and Prins Karls Forland, Svalbard. Norsk Polarinstitutt Skrifter, 167, 145-169.Manby, G. M., 1986. Mid-Palaeozoic metamorphism and polyphase deformation of the Forland Complex, Svalbard. Geological Magazine, 123(06), 651-663.Morris, A., 1982. Low grade (greenschist facies) metamorphism in southern Prins Karls Forland, Svalbard. Polar Research, 1982(2), 17-56.Morris, A., 1989. Distributed, right‐lateral strike‐slip in Prins Karls Forland, western Svalbard. Polar research, 7(1), 79-82. 

Structural and vibrational behaviour of pyromorphite-vanadinite solid solution series

Pyromorphite Pb5(PO4)3Cl and vanadinite Pb5(VO4)3Cl belong to the apatite supergroup. They are secondary minerals formed in the oxidation zones of lead ore deposits. Both crystallize in hexagonal symmetry with the space group P63/m (Dong et al. 2002). The crystal structure of these two minerals allows to accommodate both metal cations and anionic complexes. It is the reason, why pyromorphite and vanadinite forms solid solution series. Isovalent replacement of P with V is one of the most common anionic substitution. Lead apatites are one of the least soluble along apatites group minerals and characterized by high thermal stability (Dong et al. 2002, Flis et al. 2011). Characteristic properties of apatite structure cause that these minerals are successfully used in many fields, especially for the immobilization of toxic waste and lead-contaminated soil (Ma et al. 1993, Chen et al. 1997, Dong et al. 2002, Kim et al. 2005). So far, pyromorphite and mimetite are the most known and used for the immobilization of lead. Pyromorphite and mimetite are isostructural with vanadinite, therefore it has been predicted that this mineral is also important for the environment. Accordingly, the aim of this study was to characterize of the pyromorphite-vanadinite solid solution series. This research present systematic changes in the structure of these minerals. Pure pyromorphite and vanadinite and minerals with intermediate compositions Pb5(TO4)3Cl, where T = P + V, of various P/V ratios were synthesized  from aqueous solutions at 298 K and pH = 3.5. Synthetic solids were analyzed by X-Ray diffraction (XRD), infrared absorption spectroscopy (FTIR) and Raman spectroscopy. Based on the X-Ray analysis, it was found that synthetic precipitates represent homogeneous phases of pyromorphite and vanadinite, which have intermediate chemical composition. Diffraction peaks of pyromorphite-vanadinite solid solution series were shifted due to replacement of PO4 by VO4. Replacement of PO4 by VO4 anions is causing changes in the structure of apatite and hence these shifts. Unit cell parameters of studied solid solutions show a linear variation. In the FTIR and Raman spectra of pyromorphite-vanadinite solid solutions series, the bands which are characteristic for vibrations of P-O bonds of the PO4 tetrahedra as well as vibrations of V-O bonds of the VO4 tetrahedra appeared. Analysis of Mid-IR spectra and Raman spectra also allowed to observe correlation between the band positions and the extent of the anionic substitution among the studied series. The structure of pyromorphite and vanadinite is generally similar, although they vary in chemical composition. Causes of variability are probably connected with the properties of individual ions.The project was financed with resources of the National Science Centre, Poland, granted based on decision no. DEC-2013/09/N/ST10/00677

Immobilizacja Pb(II) przez krystalizację piromorfitu na galenie w obecności nawozów fosforanowych Immobilization of Pb(II) by crystallization of pyromorphite on galena in the presence of phosphate fertilizers /

Tyt. z nagłówka.Pozostali autorzy artykułu: Tomasz Bajda, Małgorzata Wegner, Olaf Borkiewicz.Bibliografia s. 269.Dostępny również w formie drukowanej.ABSTRACT: In the presence of PO/4/3- and Cl/- ions, dissolution of galena PbS is accompanied with crystallization of pyromorphite Pb5(PO4)3Cl. This results in reduction of Pb(II) concentration which is more effective at pH 4 and 5 than at pH 2 and 3. When commercial fertilizers (Azofoska and Superfosfat) are used, the mechanism of Pb immobilization is identical. Azofoska is more effective and lowers the concentration of Pb below 0.05 mg/dm3. KEYWORDS: reclamation, neutralization of contamination with Pb, soil pollution. SŁOWA KLUCZOWE: rekultywacja, neutralizacja skażeń Pb, zanieczyszczenie gleb