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Коэффициенты сокристаллизации в водных растворах солей и их температурные изменения

Журнальные статьи

Aakeroey C.B. et al. Mapping out the synthetic landscape for re-crystallization, co-crystallization and salt formation // Crystengcomm. 2010. Vol. 12, № 12. P. 4231–4239.

In order to examine the balance between co-crystallization and proton transfer in a set of acid-base reactions, molecular electrostatic potential (MEP) surface calculations for substituted pyridines were correlated with their ability to communicate with a series of carboxylic acids via intermolecular interactions in the solid state. The calculated (AM1) charges on the hydrogen-bond acceptor in these N-heterocyclic compounds provide overall excellent guidelines for predicting when a salt or a co-crystal will form. The charges can also be related to the supramolecular yield of the reactions between seven derivatives of 2-aminopyridine and fifteen aromatic/aliphatic carboxylic acids. The outcome of all reactions was screened using IR spectroscopy, and twelve crystal structures were used to verify the spectroscopic assignments and to examine the exact nature of the primary intermolecular interactions.

Adabi M.H. A re-evaluation of aragonite versus calcite seas // Carbonates and Evaporites. 2004. Vol. 19, № 2. P. 133–141.

Some workers have argued that the mineralogy of ancient carbonates may have been different from that of modern sediments, with calcite being considered the dominant mineral during the Ordovician, Devonian-mid Carboniferous, and Jurassic-Cretaceous to Early/Middle Cenozoic (e.g. Sandberg 1983; Wilkinson and Algeo 1989). Variation in carbonate mineralogy has been related to the position of global sea level (emergent or submergent modes, Wilkinson et al. 1985), change in rates of seafloor spreading (e.g. Mackenzie and Pigott 1981; Hardie 1996), PCO2 level (e.g. Sandberg 1985; Mackenzie and Morse 1992; Hallock 1997) and Mg/Ca ratios related to spreading rate (e.g. Stanley and Hardie 1998). However, other researchers suggest that the assumption of change of original carbonate mineralogy through time needs to be re-evaluated in the light of mineralogical change that is related to water temperature or latitudes (e.g. Nelson 1988). Evaluation of Ordovician (Arenig to Ashgill) Gordon Group carbonates of Tasmania (Australia), based on petrographic (e.g. abundant Chlorozoan biota, and oomold texture) and geochemical criteria (such as high Sr/Na ratios) indicated that aragonite (not calcite) was the predominant mineral in these warm water, subtropical carbonates (Rao 1990). Petrographic (e.g. presence or absence of aragonite relicts, abundant acicular to fibrous isopachous marine cement, presence of diffuse laminae and a number of spalled ooids) and geochemical evidences (such as elevated Sr) in the Upper Jurassic Mozduran limestone, in Kopet-Dagh Basin in northeast Iran, showed variation in carbonate mineralogy, in spite of similar atmospheric PCO2 level, global sea-level and tectonic setting. This is evidenced by aragonite occurring in the shallowest part of the basin (Adabi and Rao 1991) and mainly calcite with some aragonite forming in the relatively deeper water (below wave base) (Adabi 1997). Carbonate mineralogy in Recent shallow marine carbonates, and in experimental studies, varies with seawater temperature. In the Recent, aragonite is the predominant mineral in warm, shallow marine carbonates and calcite the dominant mineral in marine cool water carbonates (James and Clarke 1997). Therefore, variations in carbonate mineralogy in the Mozduran limestone are attributed to seawater temperature assuming invariant seawater chemistry prevailed in the Upper Jurassic. Several Jurassic examples show variations in ooid carbonate mineralogy, such as the Upper Jurassic Smackover oolite of the Gulf Coast region (southern Arkansas and northern Louisiana) and Upper Jurassic ooids in the Purbeck limestones of Swiss and French Jura. These results are not in agreement with the concept of a "calcite sea" during the Ordovician and the Upper Jurassic periods. Very recently, Westphal and Munnecke (2003) showed that in spite of the tendency of abiotic precipitates (Sandberg 1983) and skeletal mineralogy (Stanley and Hardie 1999) to follow the general trend of calcite seas and aragonite seas, organisms with calcite and aragonite mineralogy coexisted throughout the Phanerozoic. They have examined the temporal and spatial distribution of limestone-marl alternations in Ordovician, Jurassic and Cretaceous (times of calcite seas). Limestone-marl alternations are most abundant in settings that favored aragonite production and accumulation analogous to the modern environment (Westphal and Munnecke 2003). If the above observations confirmed, the proposed secular variation in Phanerozoic carbonate mineralogy needs to be re-evaluated.

Balter V., Lecuyer C. Determination of Sr and Ba partition coefficients between apatite and water from 5°C to 60°C: A potential new thermometer for aquatic paleoenvironments // Geochimica et Cosmochimica Acta. 2004. Vol. 68, № 3. P. 423–432.

Apparent partition coefficients of Sr and Ba between calcium phosphate and water were measured experimentally for temperature ranging from 5°C to 60°C. Calcium phosphates were precipitated from an aqueous mixture of Na2HPO4 · 2H2O (10-2 M) and CaCl2 · 2H2O (10-2 M). Spiked solutions of Sr or Ba were introduced into the CaCl2 · 2H2O solution at Sr/Ca and Ba/Ca ratios of 0.1. The experiment consisted in sampling the liquid and solid phases after 1, 6, 48, and 96 h of interaction. The amorphous calcium phosphate (ACP) precipitated early in the experiment was progressively replaced by hydroxylapatite (HAP), except at 5°C where brushite (di-calcium phosphate di-hydrate or DCPD) was formed. We observed that the crystallinity of the solid phase increased with time for a given temperature and increased with temperature for a given time of reaction. With the exception of the experiment at 5°C, yield (R%) and apparent partition coefficients (Ka-wSr/Ca and Ka-wBa/Ca) both decreased with increasing reaction time. After 96 h, R%, Ka-wSr/Ca and Ka-wBa/Ca were observed to be constant, suggesting that the solid phases were at steady-state with respect to the aqueous solutions. The thermodependence of Sr and Ba partitioning between apatite and water at low temperature could therefore be calculated: Log(Ka-wSr/Ca) =0.42±0.04(103T-1)-1.87±0.12 (r2=0.94) Log(Ka-wBa/Ca) =1.96±0.06(103T-1)-7.19±0.20 (r2=0.99) We also performed competition experiments between Sr and Ba. The thermodependence of the Sr/Ba partitioning between apatite and water was calculated after 96 h of reaction: Log(Ka-wSr/Ba)=-0.75±0.04(103T-1) +2.39±0.14(r2=0.97) This relationship reveals a discrimination of Ba in favor of Sr during their incorporation into HAP. Temperature trends deduced from the Ba/Ca of fish teeth recovered from the K/T boundary mimic those estimated from ?18O(PO4) measurements carried out on the same sample. Unless Sr, Ba and Ca contents of biogenic apatites are modified during diagenesis, their elemental ratios could be used as new and attractive thermometers of aquatic paleoenvironments.

Bottcher M.E., Dietzel M. Metal-ion partitioning during low-temperature precipitation and dissolution of anhydrous carbonates and sulphates // European Mineralogical Union Notes in Mineralogy. 2010. Vol. 10, № 1. P. 139–187.

Anhydrous carbonate and sulphate-bearing solids are formed on Earth under very different environmental conditions and are the most abundant constituents in so-called chemical sediments. At low temperatures, both biogenic and abiotic formation mechanisms are observed and their occurrence ranges from freshwater, via open marine to hypersaline aquatic environments. To understand individual mechanisms of mineral formation and the impact of boundary environmental conditions such as reaction temperature, composition of the aqueous mother fluid and precipitation rate, geochemical tracers such as trace metals or stable isotopes are needed. The thermodynamics of element partitioning in solid solutions-aqueous solutions (SS-AS) systems provides a frame for the evaluation of e.g. the impact of reaction kinetics, vital activity, or ionic strength. The presence of metastable phases may influence further reactions by providing the necessary reactants and surfaces for dissolution, adsorption, and reprecipitation reactions, thereby changing reaction kinetics in comparison to reactions in homogeneous solutions. The evaluation of trace-element substitution requires the combination of modelling approaches, in particular with experimental calibrations, but also empirical relationships. In this communication, the authors focus on selected binary carbonate and sulphate SS-AS systems at low temperatures. Systems involving the partitioning of Mg2+, Mn2+ and Sr2+ and others are discussed in more detail. They give a presentation of relevant current topics related to low-temperature metal-ion partitioning during complex precipitation and dissolution behaviour. The aim of this contribution is to stimulate future research in the highly relevant, low-temperature carbonate and sulphate SS-AS systems.

Bruce R. Patterns in the compositions, properties, and geochemistry of carbonate minerals // Carbonates and Evaporites. 1999. Vol. 14, № 1. P. 1–20.

The diversity of carbonate minerals is remarkable, if largely unappreciated. For example, 277 carbonate-bearing minerals have been recognized, and among them are 158 pure carbonates of cations with valences from 1+ to 6+. The other 119 minerals additionally contain chloride, fluoride, borate, sulfate, phosphate, arsenate, arsenite, antimonate, or silicate groups, or combinations of those anions. However, combinations of anions with cations are not uniformly distributed, so that there are no bicarbonates or simple carbonates of highly-charged cations, few hydrated or OH-bearing minerals of monovalent cations, and few U-bearing carbonates with anions other than CO3 2, OH, and O2. On the other hand, simple carbonates of divalent cations, OH-bearing Al carbonates, and fluoride-bearing carbonates of rare-earth elements are remarkably numerous. Many of these trends can be related to the coordination chemistry of cations in the solutions from which these minerals form. Among nearly all the carbonate-bearing minerals, ionic potential of the cations is a major control on the extent of hydration. Degree of hydration is in turn a major control on hardness, density, and solubility. Among the simple carbonates, hardness, density, and positions of spectroscopic peaks vary linearly with cation radius or mass, although such trends usually exist only within crystallographic groups or only within cation groups defined by the periodic table. In contrast, geochemical parameters, such as solubility and fractionation of oxygen isotopes, vary with degree of cation fit in the 6-fold or 9-fold site of the rhombohedral and orthorhombic simple carbonates, so that there is not a linear variation with cation size. The same is true for the distribution coefficients of cations in calcite and aragonite. Patterns thus emerge among the compositions, properties, and geochemistry of the carbonate minerals, with cationic potential and type as a major influence on composition, with degree of hydration and cation radius or mass as a control on physical and spectroscopic properties, but with cation fit as the major control on geochemical parameters. These patterns allow qualitative prediction of mineral properties and help explain the origins of some of the major problems in carbonate petrology.

Cardinal D. et al. Sr/Ca, U/Ca ad ?18O records in recent massive corals from Bermuda: Relationships with sea surface temperature // Chemical Geology. 2001. Vol. 176, № 1-4. P. 213–233.

High-resolution records of Sr/Ca, U/Ca ratios and ?18O have been obtained in two recent colonies of massive corals (Diploria labyrinthiformis) from Bermuda. The three geochemical proxies display regular seasonal variations and are well correlated with each other. However, some important discrepancies are observed between the two colonies: The average seasonal variations of the three geochemical proxies are lower by almost 50% in one of the profiles, where the seasonal oscillation also displays a strong asymmetry, with narrower summer maxima. Different calculations are discussed for calibrating Sr/Ca and ?18O with sea surface temperatures (SST). We show that the method using only temperature minima and maxima is slightly more accurate and is also more reliable. Our results from Bermuda corals confirm that the temperature dependency of Sr/Ca, U/Ca and ?18O is species-dependent, as previously shown by others and that "vital effects" are clearly involved in the geochemical incorporation of trace elements in the coral skeleton. Finally, a simple model involving seasonal variation of the growth rate and a kinetic fractionation related to growth rate is presented to explain the differences between the two Bermuda colonies. It is shown that these factors may prevent corals from recording the complete temperature seasonality and could be the cause for the discrepancies observed between profiles, resulting in significant biases of the SST reconstructions.

Christov C. Temperature variable chemical model of bromide-sulfate solution interaction parameters and solid-liquid equilibria in the Na-K-Ca-Br-SO4-H2O system // Calphad-Comput. Coupling Ph. Diagrams Thermochem. 2012. Vol. 36. P. 71–81.

The experimental solubility data of bromide and sulfate minerals available in the literature are used to construct a chemical model that calculates solid-liquid equilibria in mixed systems NaBr-Na2SO4-H2O. KBr-K2SO4-H2O. and CaBr2-CaSO4-H2O from low to high solution concentration within the T = (0-100) degrees C temperature range. The solubility modeling approach based on fundamental Pitzer specific interaction equations is employed. The resulting model for mixed systems gives a very good agreement with bromide and sulfate salts equilibrium solubility data available in the literature. Temperature extrapolation of the mixed system models provides reasonable mineral solubilities at low (0 degrees C) and high temperature (up to 100 degrees C). Limitations of the mixed solutions models due to data insufficiencies at high temperature are discussed. The model for mixed system CaBr2-CaSO4-H2O at T = (0-50) degrees C was developed using pure electrolyte parameters of Ca-SO4 interactions and without including into a model aqueous species CaSO4 degrees(aq). It was showed that solution parameters fully account possible association reactions in low calcium sulfate molality regions of binary CaSO4-H2O and mixed solutions. The model presented here expands the previously published temperature dependent sodium-potassium-calcium-sulfate model by evaluating bromide-sulfate mixing solution parameters and inclusion of 5 bromide minerals precipitating within Na-K-Ca-Br-SO4-H2O system. The model predictions on the effect of bromide-sulfate mixing on the equilibrium deliquescence relative humidity (DRH) in NaBr-Na2SO4-H2O and KBr-K2SO4-H2O solutions are also given.

Christov C. Thermodynamic study of the co-crystallization of ammonium, sodium and potassium alums and chromium alums // Calphad-Comput. Coupling Ph. Diagrams Thermochem. 2003. Vol. 27, № 2. P. 153–160.

The Pitzer binary and mixing ion-interaction parameters determined in previous studies of the author were used for determining the thermodynamic characteristics of the formation process of mixed crystals of the ammonium and potassium alums, ammonium and potassium chromium alums, and of the ammonium alum and ammonium chromium alum. The ternary K2SO4-Cr-2(SO4)(3)-H2O system has been re-parameterized using a different experimental value of the pure water solubility of the potassium chromium alum. The component activities of the saturated ternary (NH4)(2)SO4Al2(SO4)(3)-K2SO4Al2(SO4)(3)-H2O, (NH4)(2)SO4Cr2(SO4)(3)-K2SO4Cr2(SO4)(3)-H2O and (NH4)(2)SO4Al2(SO4)(3)-(NH4)(2)SO4Cr2(SO4)(3)-H2O solutions and in the mixed crystalline phase were determined and the change of the molar Gibbs energy of mixing Delta(mix)G(m)(o)(s) of crystals was determined as a function of the solid phase composition. It was established that at T = 298.15 K, the mixed (K, NH4)(2)(SO4Al2)-Al-.(SO4)(3)(.)24H(2)O, (K, NH4)(2)(SO4Cr2)-Cr-.(SO4)(3)(.)24H(2)O, and (NH4)(2)SO4.(Al, Cr)(2)(SO4)(3)(.)24H(2)O crystals show negative deviations from ideal mixed crystals. The basic Pitzer ion-interaction model was used for solubility calculations in ternary (NH4)(2)SO4Al2(SO4)(3)-Na2SO4Al2(SO4)(3)-H2O, and in quaternary (NH4)(2)SO4-Na2SO4-Al-2(SO4)(3)-H2O systems, from which phases with constant stoichiometric composition (simple and double salts) crystallize. Good agreement between model calculations and experiment was found. The model predictions presented in this paper provide another step for the validation of the binary- and ternary-mixing solution parameters of our aluminum- and chromium- sulfate model.

Dietzel M., Gussone N., Eisenhauer A. Co-precipitation of Sr2+ and Ba2+ with aragonite by membrane diffusion of CO2 between 10 and 50 °C // Chemical Geology. 2004. Vol. 203, № 1-2. P. 139–151.

Aragonite is precipitated by a new CO2-diffusion technique from a Ca2+-Mg2+-Cl- solution between 10 and 50 °C. Crystallisation of aragonite instead of calcite occurs by maintaining a [Mg2+]/[Ca2+] ratio of 2 in the fluid. The dissolved inorganic carbon (DIC) is received by diffusion of CO2 through a polyethylene membrane (diffusion coefficient: DCO2 =10-6.4 cm2 s-1 at 19 °C). It is suggested that significant amounts of DIC may be transferred by diffusion of CO2 in natural systems if the CO2 gradient is high. The CO2 -diffusion technique is used as a kind of simple mixed flow reactor for the co-precipitation of barium and strontium with aragonite. The distribution coefficients of Ba2+ and Sr2+ decrease from 10 to 50 °C according to D* Ba,a =2.42-0.03595 T (°C) and D* Sr,a =1.32-0.005091 T (°C). At 25 °C, the distribution coefficients are D* Ba,a =1.5±0.1 and D* Sr,a =1.19±0.03. The effect of temperature on D* Ba,a is about one order of magnitude higher versus that on D* Sr,a. Thus, Ba2+ may be a potential paleotemperature indicator if the composition of the solution is known.

Gaetani G.A., Cohen A.L. Element partitioning during precipitation of aragonite from seawater: A framework for understanding paleoproxies // Geochimica et Cosmochimica Acta. 2006. Vol. 70, № 18. P. 4617–4634.

This study presents the results from precipitation experiments carried out to investigate the partitioning of the alkaline earth cations Mg2+, Ca2+, Sr2+, and Ba2+ between abiogenic aragonite and seawater as a function of temperature. Experiments were carried out at 5 to 75 °C, using the protocol of Kinsman and Holland [Kinsman, D.J.J., Holland, H.D., 1969. The coprecipitation of cations with CaCO3 IV. The coprecipitation of Sr2+ with aragonite between 16 and 96 °C. Geochim. Cosmochim. Acta 33, 1-17.] The concentrations of Mg Sr and Ba were determined in the fluid from each experiment by inductively coupled plasma-mass spectrometry, and in individual aragonite grains by secondary ion mass spectrometry. The experimentally produced aragonite grains are enriched in trace components ("impurities") relative to the concentrations expected from crystal-fluid equilibrium, indicating that kinetic processes are controlling element distribution. Our data are not consistent with fractionations produced kinetically in a boundary layer adjacent to the growing crystal because Sr2+, a compatible element, is enriched rather than depleted in the aragonite. Element compatibilities, and the systematic change in partitioning with temperature, can be explained by the process of surface entrapment proposed by Watson and Liang [Watson, E.B., Liang, Y., 1995. A simple model for sector zoning in slowly grown crystals: implications for growth rate and lattice diffusion, with emphasis on accessory minerals in crustal rocks. Am. Mineral. 80, 1179-1187] and Watson [Watson, E.B., 1996. Surface enrichment and trace-element uptake during crystal growth. Geochim. Cosmochim. Acta 60, 5013-5020; Watson, E.B., 2004. A conceptual model for near-surface kinetic controls on the trace-element and stable isotope composition of abiogenic calcite crystals. Geochim. Cosmochim. Acta 68, 1473-1488]. This process is thought to operate in regimes where the competition between crystal growth rate and diffusivity in the near-surface region limits the extent to which the solid can achieve partitioning equilibrium with the fluid. A comparison of the skeletal composition of Diploria labyrinthiformis (brain coral) collected on Bermuda with results from precipitation calculations carried out using our experimentally determined partition coefficients indicate that the fluid from which coral skeleton precipitates has a Sr/Ca ratio comparable to that of seawater, but is depleted in Mg and Ba, and that there are seasonal fluctuations in the mass fraction of aragonite precipitated from the calcifying fluid ("precipitation efficiency"). The combined effects of surface entrapment during aragonite growth and seasonal fluctuations in "precipitation efficiency" likely forms the basis for the temperature information recorded in the aragonite skeletons of Scleractinian corals.

Gryta M. Calcium sulphate scaling in membrane distillation process // Chem. Pap. 2009. Vol. 63, № 2. P. 146–151.

Formation of precipitates containing CaSO(4) during membrane distillation, applied to the concentration of aqueous salt solutions, is discussed in this paper. It was found that the concentration of SO(4)(2-) ions in such solutions should not exceed 600 mg L(-1) when they are subjected to concentration. However, concentration of sulphates at the level of 800 mg L(-1) in the feed is permissible provided that the excess of CaSO(4) is removed in a crystallizer. Crystallisation of salts, mainly CaSO(4) center dot 2H(2)O, on the surface and inside the membrane was observed at higher feed concentrations, causing damage of the module. Precipitation of calcium sulphate was also observed during the production of demineralised water when high values of the water recovery coefficient (above 90 %) were used. In this case, the formed precipitate also contained CaCO(3), the co-precipitation of which significantly changed the properties of the scaling layer. The precipitate containing both CaSO(4) and CaCO(3) was formed mainly on the membrane surface and it could easily be removed by rinsing the module with a HCl solution.

Guo K. et al. Co-Crystallization in the Caffeine/Maleic Acid System: Lessons from Phase Equilibria // Cryst. Growth Des. 2010. Vol. 10, № 1. P. 268–273.

Previous studies of the cocrystallizing system caffeine-maleic acid has shown the existence of 1:1 and 2:1 cocrystals together with it new polymorph of maleic acid. In this current work. we have attempted to rationalize this behavior through measurement of the binary and ternary phase diagrams

Hchaichi H., Hannachi A. Co-precipitation in multiple-effect distillers at nonconventional temperatures // Desalination and Water Treatment. 2015. Vol. 55, № 12. P. 3277–3284.

A model has been developed to predict alkaline scale formation in seawater multiple-effect distillers (MED) at high top brine temperature (TBT). The effects of changes in solution composition due to CO2 release on the formation of crystalline scales in seawater evaporators are studied. Supersaturations of scaling salts are calculated by applying mass and charge conservation equations while considering chemical reactions involved in the process. Pitzer model was used for the activity coefficient calculations. Simulations allowed predicting co-precipitation of alkaline scale: magnesium hydroxide and calcium carbonate. These salts are responsible for scale build-up. Simulation results matched well with the reported experimental data for high TBT in MED.

Jacobs T. et al. Co-crystallization of Ionic and Neutral Supramolecular Motifs Derived from Identical Components // Cryst. Growth Des. 2009. Vol. 9, № 3. P. 1284–1286.

The concept of co-crystallization usually applies to the coexistence of two or more different types of molecule in the same crystal, but at a higher level of complexity it is possible to define a parallel concept where a crystal is composed of two or more recognizably different supramolecular assemblies. We describe the structure of an adduct formed between Dianin's compound and ethylene diamine. This structure consists of two recognizably different supramolecular assemblies of these components. Furthermore, these two forms have each previously been observed to exist in isolation. Therefore, it is reasonable to make the comparison with conventional co-crystals where two or more compounds that can exist separately form a crystalline adduct (often termed a "molecular complex").

Kirkova E., Djarova M., Donkova B. Inclusion of isomorphous impurities during crystallization from solutions // Prog. Cryst. Growth Charact. Mater. 1996. Vol. 32, № 1-3. P. 111–134.

Developments in the field of inclusion of isomorphous impurities during crystallization from solutions are reviewed. The main features of distribution coefficients like effective, equilibrium and thermodynamic cocrystallization coefficients are presented and discussed. From an analysis of the data, some general characteristics of the influence of various factors, such as solubility of components, ionic radii, enthalpy of dehydration, electronegativity, complex formation of the ions and temperature, on the equilibrium cocrystallization coefficient are given.

Kuchler-Krischun J., Kleiner J. Heterogeneously nucleated calcite precipitation in Lake Constance. A short time resolution study // Aquatic Sciences. 1990. Vol. 52, № 2. P. 176–197.

Calcite precipitation in spring 1988 in Lake Constance was studied by measuring physical, chemical and biological parameters in daily intervals. Algae triggering calcite precipitation in spring after an induction period of 1 day were Stephanodiscus hantzschii and Chlorella spp. whereas no time lag concerning maximum saturation index was observed. Number and size distribution of crystals were determined by microscopical methods. Simple equations were given for estimation of the precipitated mass of calcite by approximating the volume of calcite crystals by simple geometric bodies and multiplying by crystal numbers. Particulate calcium was analysed after dissolving suspended matter and amounted to 90% of inorganic dry weight. Crystals were observed for the first time after dissolved phosphorus was no more detectable.

Lemmerer A., Adsmond D.A., Bernstein J. An Investigation of the Hydrogen-Bond Preferences and Co-crystallization Behavior of Three Didonor Compounds. // Cryst. Growth Des. 2011. Vol. 11, № 5. P. 2011–2019.

We assess the suitability of the three didonor compounds as building blocks for ternary co-crystals of the type (didonor)(monoacceptor)(2). A Cambridge Structural Database (CSD) survey was carried out to analyze the hydrogen-bond connectivity and develop a strategy for the preparation of the desired co-crystal. Six specific compounds were selected and crystals were grown from 1:1 and 1:2 solutions of didonor compounds (m-hydroxybenzoic acid, p-hydroxybenzoic acid, and racemic mandelic acid) and acceptor compounds (acridine, triphenylphosphine oxide, and nicotinamide) leading to three co-crystals (m-hydroxybenzoic acid) center dot (triphenylphosphine oxide)(2) (1), ((RS)-mandelic acid) center dot (acridine) (2) and (p-hydroxybenzoic acid) center dot (nicotinamide) (3). Characterization by single-crystal structure determination confirms the success of this design strategy.

Mavromatis V. et al. Characterization of boron incorporation and speciation in calcite and aragonite from co-precipitation experiments under controlled pH, temperature and precipitation rate // Geochimica et Cosmochimica Acta. 2015. Vol. 150. P. 299–313.

About 20years ago, the boron isotopic composition of marine carbonates was proposed as a proxy of ancient seawater pH. Since that time, a large body of studies has used boron isotopes in carbonates to reconstruct seawater paleo-pH and atmospheric paleo-CO2 concentration. To date, however, no systematic investigation of the physicochemical parameters that control boron incorporation in calcite and aragonite (pH, temperature, precipitation rate, etc.) has been performed. To fill this gap, we have experimentally investigated the inorganic co-precipitation of boron with calcite and aragonite at 5 and 25°C in the presence and absence of seed crystals and over the pHNBS range 7.4<pH<9.5 in 0.1 or 0.2M NaCl solutions. The boron partition coefficient, DB, between CaCO3 and the fluid is defined as:DB=(XB/XCO3)CaCO3([B]/[CO32-])fluidwith Xi and [i] standing for the mole fraction and molality of the ith species in the solid and fluid, respectively. DB measured in this study are very small (DB?10-3 and ?10-4 for aragonite and calcite, respectively) and exhibit a strong dependence on the solution pH and the calcium carbonate precipitation rate. High field 11B MAS NMR analyses of the precipitated carbonates show that boron in aragonite is mostly in the form of tetragonal B (?85% [IV]B) but that both trigonal and tetragonal B are present in calcite. A significant amount of tetragonal boron in calcite may be in non-lattice (defect) sites, in addition to the structural site. The relative abundance of [III]B and [IV]B in calcite is independent of the parent solution pH but appears to decrease with increasing precipitation rate. The change in boron coordination during its incorporation in calcite and its distribution in, at least, two different sites strongly suggest that the mechanisms controlling B incorporation in this mineral are more complex than for aragonite. It follows that calcite-based calibrations may be less reliable than aragonite calibrations for ocean paleo-pH reconstructions.

Mikhailov M.A. The co-crystallization of beryl-structure compounds in the Al2Be3Si6O18-Mg,Ca/F,Cl system // J. Cryst. Growth. 2005. Vol. 275, № 1-2. P. E861–E866.

An Al2Be3Si6O18 - Mg, Ca/F, Cl flux system unused earlier has been chosen for the synthesis of beryl (Al2Be3Si6O18) and its varieties. In such a case of disregarding the well-known rules of the choice of a solvent, the following crystallization features of beryl have been revealed: (1) the beryl co-crystallizes successively and/or simultaneously with isostructural beryllian indialite (Mg2BeAl2Si6O18); (2) the bulk of beryl crystals is formed only in regions with high concentration of a flux; (3) the solution-melt liquates; (4) the solvent evaporates intensively. The advantages of the flux proposed are both the possibility of using inexpensive steel crucibles and good chromophoric properties of Cr, V, and Ti. Ratios of constitutient elements and some additive those between beryl and beryllian indialite, both grown simultaneously, and between pinacoid and prism in crystals of these compounds are reported.

Moore C.H., Wade W.J. Carbonate diagenesis: Introduction and tools // Developments in Sedimentology. 2013. Vol. 67. P. 67–89.

The three diagenetic realms in which porosity modifications (e.g., dissolution, cementation, compaction) take place are the marine, meteoric, and subsurface environments.The meteoric environment-with its dilute waters, easy access to CO2, and wide range of saturation states with respect to carbonate phases-has high potential for porosity modification, including destruction by cementation and generation of secondary porosity by dissolution.Modern shallow-marine environments are particularly susceptible to porosity destruction by cementation due to high levels of supersaturation of marine waters relative to metastable carbonate minerals. Decreasing saturation with depth can lead to development of secondary porosity by dissolution of aragonite. In the geologic past, shallow-marine waters were often undersaturated with respect to aragonite.The subsurface environment is marked by loss of porosity through compaction and related cementation. Thermal maturation and degradation of hydrocarbons and the slow flux of basinal fluids during progressive burial drive later porosity modification by cementation and modest local dissolution.Recognition and differentiation of the porosity modification history of carbonate rocks is aided by a number of analytical tools.Petrography enables us to reconstruct the sequence of relatively timed diagenetic events responsible for porosity modifications. Trace element and stable isotope analyses of cements and dolomites provide insight into the types of waters involved in these events. Two-phase fluid inclusions are used to estimate temperatures of cement or dolomite formation and the composition of precipitating or dolomitizing fluids.The definitiveness of trace element analysis is often limited by uncertainties in distribution coefficients, temperature fractionation effects, or low concentration values. Two-phase fluid inclusion studies also pose significant problems (e.g., stretching of inclusions during burial, recognition of primary inclusions, and accuracy of pressure corrections). Therefore, these tools should be used to provide constraints on assessing environments of diagenetic events, within an appropriate petrographic/geologic framework.The continuing development of new instruments and techniques (e.g., the ion probe, clumped isotope analysis) holds great promise for the future of geochemical analyses in diagenetic studies.

Morse J.W., Arvidson R.S., Luttge A. Calcium carbonate formation and dissolution // Chemical Reviews. 2007. Vol. 107, № 2. P. 342–381.

An overview is given of the thermodynamics and kinetics of CaCO3 formation and dissolution and how surface and nanoparticulate chemistry are important in understanding reactivity. Topics covered are major marine carbonate materials, carbonate mineral precipitation and dissolution kinetics relevant to seawater, oceanic sources of marine carbonates, dissolution of CaCO3 and response of carbonate-rich sediments to the acidification of the ocean due to rising atmospheric pCO2.

Morse J.W., Bender M.L. Partition coefficients in calcite: Examination of factors influencing the validity of experimental results and their application to natural systems // Chemical Geology. 1990. Vol. 82, N3-4. P. 265–277.

Partition coefficients of metals in calcite have been of great interest in the study of the geochemistry of sedimentary carbonate mineral deposition and diagenesis. However, they are not equivalent to thermodynamic constants and generally represent phenomenological measurements under a given set of conditions. In recent years a number of factors, which were not previously considered of importance, have been found to exert major influences on the relation between the compositions of solutions and the calcites which precipitate from them. In this paper, we examine the complexities associated with the coprecipitation of metals in calcite using the behavior of Sr and Mg, which have received the most detailed study, as examples. Given the growing number of parameters which have been found to exert major influences on partition coefficients, and the failure of experimentally determined partition coefficients to predict even the composition of modern marine cements, we recommend that they be applied to natural systems with considerable caution.

Povar I., Spinu O. Correlation between global thermodynamic functions and experimental data in multicomponent heterogeneous systems // Canadian Journal of Chemistry. 2015. Vol. 94, № 2. P. 113–119.

The correlation between global thermodynamic functions and such experimental data, which quantitatively characterize the precipitation-dissolution processes of sparingly soluble compounds, as the degree of precipitation and residual concentrations of the solid-phase components in saturated solutions under real conditions, taking into account the complex formation reactions, has been deducted. The paper intends also to introduce widely formal thermodynamic methods for forecasting the conditions of mutual transformation of solid phases through chemical synthesis by precipitation methods, optimization of coprecipitation methods, fractional precipitation from homogeneous solutions, and separation and analysis of chemical compounds. Within the method of residual concentrations, the thermodynamic parameters of the process of precipitating cadmium ions with potassium decanoate from acid and alkaline solutions for different temperatures were investigated. On the basis of the experimentally determined degree of precipitation and its dependence on temperature, the temperature coefficients and overall thermodynamic characteristics of the precipitation process (?HS sum, ?GS sum, and T?SS sum) were determined. The optimum conditions of the investigated process of precipitation have been established.

Prieto M. Thermodynamics of ion partitioning in solid solution-aqueous solution systems // European Mineralogical Union Notes in Mineralogy. 2010. Vol. 10, № 1. P. 1–42.

While the study of ion partitioning in solid solution-aqueous solution (SS-AS) systems has garnered scientific attention for decades, the terminologies used in ion-partitioning studies are often inconsistent. Moreover, the equilibrium thermodynamics underlying the partitioning process is often disregarded or misunderstood, although this background is indispensable in interpreting effective (non-equilibrium) distribution of substituting ions between minerals and their growth environments. Here, after an introduction to the different terminologies and definitions, the equilibrium thermodynamics of ion partitioning is reviewed for the simplest case of solid solutions with isostructural end-members and one mixing position per formula unit. Variations of the equilibrium distribution coefficients with changes in the background solution or in the composition of the solid as well as the methods to determine equilibrium values are discussed in depth. The simplifications when one of the substituting ions occurs in trace amounts (dilute solid solutions) and the effect of temperature are introduced in a later section, followed by a discussion of the thermodynamic treatment of more complex SS-AS systems: ion partitioning involving solids with more than one mixing position per formula unit, solid solutions with non-isostructural end-members, heterovalent substitutions, etc. Finally, the concept of supersaturation in SS-AS systems is introduced as a fundamental parameter to interpret non-equilibrium partitioning.

Rosenberg Y.O. et al. Nucleation and growth kinetics of RaxBa1-xSO4 solid solution in NaCl aqueous solutions // Geochimica et Cosmochimica Acta. 2014. Vol. 125. P. 290–307.

Co-precipitation of Ra and Ba in barite (i.e., the formation of a RaxBa1-xSO4 solid solution) has long been established as an important process that has the potential to control Ra concentration. This process is commonly described by a distribution model. Ample studies have shown that the key parameter of this model, the partition coefficient, varies in the range of 1-2 as a function of temperature, salinity and precipitation kinetics of the RaxBa1-xSO4 solid solution. This roughly twofold change in the partition coefficient may lead to large differences in the concentration of dissolved Ra.The present study systematically investigated the co-precipitation kinetics of the RaxBa1-xSO4 solid solution from aqueous solutions up to 5.9 molkgH2O-1 NaCl, circum-neutral pH and at ambient temperature. Laboratory batch experiments designed to follow the nucleation of the RaxBa1-xSO4 solid solution and the co-precipitation kinetics of Ba and Ra from aqueous solutions which were initially supersaturated with respect to barite (degree of supersaturation, ?barite=20±2).The following empirical law describes the dependence of the activity-based partition coefficient, KD,barite?, on the degree of supersaturation, ?barite:KD,barite?=(1.99±0.05)-(0.58±0.06)·log(?barite).This empirical law is in good agreement with other literature data. The outcomes of the empirical law are compared to the prediction of a model for the nucleation of two-dimensional islands.

Rosenberg Y.O., Metz V., Ganor J. Radium removal in a large scale evaporitic system // Geochimica et Cosmochimica Acta. 2013. Vol. 103. P. 121–137.

The removal of radium during co-precipitation with barite (BaSO4) (i.e., the precipitation of a (Ra,Ba)SO4 solid solution) is an important process with many geochemical applications. During the last century the precipitation of (Ra,Ba)SO4 solid solution was extensively studied in laboratory experiments at different temperature and salinities. The outcome of such small scale experiments often serves in theoretical safety assessments simulation, but was hardly tested over large scale field systems.In this study the precipitation of Ra was investigated in a large scale field system and found to be controlled by the formation of a (Ra,Ba)SO4 solid solution. The results are comparable to laboratory based studies conducted with the same solution. The field system is comprised of six sequential evaporation ponds and has a total volume of ?3.25?105m3. In the ponds a reject brine of a desalination plant is evaporated. The non-evaporated brine has an ionic strength of 0.7m, 226Ra concentration of ?12Bqkg-1, and it is oversaturated with respect to gypsum, celestite and barite. Upon its evaporation the ionic strength increases up to 12m, and a total amount of ?4?106kgyear-1 of sulphate minerals precipitates.Chemical analysis of solid samples collected from the ponds revealed that the precipitation of Ra is concurrent with Ba, indicating on the formation of a (Ra,Ba)SO4 solid solution. A detailed mass balance of the different solutes in the brine of the ponds allowed us to quantitatively study the effects of ionic strength and precipitation kinetics on the (Ra,Ba)SO4 solid solution composition. The results of the present field study were comparable to laboratory based experiments, suggesting that in the complex field system, as in the lab, the same factors affect the formation of the (Ra,Ba)SO4 solid solution.It is shown that as a result of both ionic strength and kinetic effects the solid solution composition is less Ra enriched; i.e., the concentration-based partition coefficient, K'D,barite, decreased from its so-called thermodynamic value (1.8) to ?1. Consequently, the removal of Ra through the precipitation of the (Ra,Ba)SO4 solid solution is attenuated and Ra concentration in the aqueous solutions can be as much as 300% higher than anticipated if K'D,barite would have been equal to 1.8. By calculating the activity-based partition coefficient, K?D,barite, both effects could be separated and studied quantitatively. It is shown that an increase of ?1 order of magnitude in barite precipitation rate leads to a decrease in the value of K?D,barite from ?1.8 to ?1.

Rosenthal Y., Boyle E.A., Slowey N. Temperature control on the incorporation of magnesium, strontium, fluorine, and cadmium into benthic foraminiferal shells from Little Bahama Bank: Prospects for thermocline paleoceanography // Geochimica et Cosmochimica Acta. 1997. Vol. 61, № 17. P. 3633–3643.

Surface sediments from Little Bahama Bank (LBB), intersecting the subtropical thermocline, were used to assess the influence of temperature on the incorporation of Mg, Sr, F, and Cd into shells of benthic foraminifera. Samples were obtained from twelve box cores along the southern slope of LBB, covering a temperature range of 18-4.5°C between 301 and 1585 m. We studied the composition of ten calcitic and one aragonitic species, which are often used in paleochemical reconstructions. Mg/Ca ratios decrease with increasing water depth in all benthic species, both with calcitic and aragonitic mineralogy, showing a strong correlation with water temperature. Similar decrease is seen in Sr/Ca but with no correlation with temperature. None of the benthic species studied here exhibits a depth or temperature related change in F/Ca. Similar trends are observed when using an ocean-wide dataset, which includes shallow and deep core tops (300-5000 m). We suggest that temperature is the primary control on the Mg content of benthic foraminifera. Based on inorganic precipitation experiments and thermodynamic considerations, presented here, a 30-40% decrease in the Mg distribution coefficient in calcite may be expected as a result of a temperature change from 25°C to 5°C, which is about half the observed change in LBB. A calibration curve applied to C. pachyderma data from core tops along the slope of Little Bahama Bank suggests that water temperature may be inferred from Mg/Ca ratios with an uncertainty of about ±0.8°C. Therefore, the Mg content of benthic foraminifera may provide a new, independent temperature proxy for studying shallow waters paleoceanography. The linear decrease in Sr/Ca with increasing depth is not correlated with temperature; the trend is constant from the ocean surface down to 5 km, suggesting that pressure related effects on the calcification process are a more likely explanation than post-depositional dissolution. Mg/Ca ratios in aragonitic shells of H. elegans covary with temperature, in accord with recent observations from corals. In contrast, the Sr and F chemistry of H. elegans is very different than that of corals and inorganically precipitated aragonites. The disparities between the elemental composition of biogenic and inorganic phases and the large intergeneric and interspecific differences observed both in planktonic and benthic foraminifera implicate temperature related physiological processes in regulating the coprecipitation of elements in foraminiferal shells. Our work demonstrates that Cd/Ca ratios of shallow calcitic species reflect the vertical distribution of nutrients; no significant influence of temperature on the partitioning of Cd into the shells was found. Our data extend the previous deep water calibration (Boyle, 1992), thereby allowing for the reconstruction of the nutrient chemistry of shallow thermocline waters. u

Smolik M. Cocrystallization of low ammounts of M2+ ions during CoSO 4·7H2O crystallization // Journal of the Chilean Chemical Society. 2003. Vol. 48, № 3. P. 13–18.

The equilibrium cocrystallization coefficients DM/CoSO4.7H2O of low amounts (10-3- 10-1%w/w) of M2+ ions (M2+ = {Ni2+, Mg2+, Cu2+, Zn 2+, Fe2+, Mn2+, Cd2+, Ca 2+)) with CoSO4·7H2O have been determined with the method of long-time stirring of crushed CoSO 4·7H2O crystals in their saturated solution at 20°C and compared with coefficients determined by means of the method of isothermal decreasing of supersaturation during 3 - 360 hours of stirring. This enabled the time needed to reach equilibrium to be found. It is different for different microcomponents. The determined cocrystallization coefficients are diverse: from <0.008 for Ca2+ to 1.20 for Fe2+. Their dependence on some physicochemical and crystal-chemical properties of both sulfate hydrates (CoSO4·7H2O and MSO 4·nH2O) and metal M2+ ions has been discussed. They depend mainly on solubility in water and structure of corresponding sulfate hydrates as well as on radii of M2+ ions. It is possible to calculate cocrystallization coefficients with empirical formula based on determined relationships between some of the considered properties of macrocomponent and microcomponents and DM/CoSO4.7H2O coefficients at the average relative error not exceeding 10%.

Smolik M., Kowalik A. Co-crystallization of trace amounts of M2+ ions with ZnSeO4 center dot 6H(2)O at 25 degrees C // J. Cryst. Growth. 2010. Vol. 312, № 4. P. 611–616.

The distribution coefficients D-2/1 (Henderson-Kracek, Chlopin) of trace amounts of ions M2+ ( Ni2+, Mg2+, Cu2+, Co2+, Mn2+, Cd2+, Ca2+) with ZnSeO4 center dot 6H(2)O have been determined. The values of D-2/1 range from 2.93 (for Ni) to < 0.03 (for Ca), but most of them are nearly I and corresponding ions cannot be effectively removed from ZnSeO4. 6H(2)O during its crystallization. The dependences of coefficients on various chemical and crystal chemical factors have been analyzed. It has been found that ionic radii. parameter p as well as number of molecules of crystallizing water affect significantly D-2/1 coefficient. It has been proved possible to derive an empirical formula, which permits estimating D-2/1 coefficients at average relative error not exceeding 25%.

Smolik M., Kowalik A. Equilibrium coefficients of co-crystallization of M2+ ions with MgSeO4 center dot 6H(2)O and their dependences on various physicochemical factors // Cryst. Res. Technol. 2011. Vol. 46, № 1. P. 74–78.

Equilibrium co-crystallization coefficients of low amounts of M2+ ions (M2+ = {Ni2+, Cu2+, Co2+, Zn2+, Mn2+, Cd2+}) with MgSeO4 center dot 6H(2)O at 25 degrees C have been determined. Their values are comprised in the range: 0.058 (for Cd) < k(eq) < 1.57 (for Co) and depend on some physicochemical and crystal chemical properties of both: co-crystallizing salts (MSeO4 center dot nH(2)O) and co-crystallizing ions (M2+). These dependences are sometimes such strong, that they make it possible to derive simple formulae permitting estimation of k(eq) coefficients at average error not exceeding 17%.

Wu L. et al. Removal of strontium from liquid waste using a hydraulic pellet co-precipitation microfiltration (HPC-MF) process // Desalination. 2014. Vol. 349. P. 31–38.

Hydraulic pellet co-precipitation microfiltration (HPC-MF) process was developed for the treatment of radioactive wastewater. Strontium was removed by forming compact crystal particles when sodium carbonate, ferric chloride and calcium carbonate were used as the precipitating agent, flocculating agent and seed crystal, respectively. When the seed crystal concentration was 0.340g·L-1, the mean and highest decontamination factors (DFs) were 842 and 1000, respectively. The concentration factor (CF) was greater than 2650. The hybrid process eliminated difficulties associated with the mechanical equipment, radiation protection and precipitate concentration; besides, it achieved efficient and stable strontium removal. Furthermore, the strontium removal mechanism was fully revealed. The transfer of Sr2+ to the solid phase was primarily completed in the hydraulic reactor. The microfiltration process was essential to not only ensure stable separation efficiency but also further improve DF. Sr2+ was transferred from the liquid phase into the solid phase by being incorporated into the calcium carbonate crystalline lattice, which formed a strontianite solid solution that was removed by subsequent solid-liquid separation. The strontium concentration exhibited an exponential decrease. A higher seed crystal concentration resulted in faster precipitation kinetics, a shorter equilibrium time and a lower effluent strontium concentration.

Yoshida Y., Yoshikawa H., Nakanishi T. Partition coefficient of Ra and Ba in calcite // Geochemical Journal. 2008. Vol. 42, № 3. P. 295–304.

Homogeneous partition coefficients (D) for Ra and Ba in calcite were determined from coprecipitation experiments using the Continuous Addition Method (CAM). The D-values derived for Ra and Ba are: DRa=(1.5±0.6)?10-1 and DBa=(1.6±1.1)?10-2. Although these data were derived at low precipitation rates (R) for calcite (R < 9 nmol mg-1min-1), the solutions were significantly oversaturated in calcite. Values of D should, ideally, be derived at equilibrium and hence the effect of oversaturation should be examined. Therefore, a coprecipitation experiment using the Free Drift Method (FDM) with slow degassing was also carried out. This experiment occurs under conditions that are only slightly oversaturated and the rate of coprecipitation was confirmed to be slow compared to dissolution and precipitation at the calcite surface. The resultant heterogeneous partition coefficients showed good agreement with homogeneous partition coefficients derived by CAM. This indicates that the oversaturation in CAM did not affect partitioning of these metals in calcite and that the derived D-values represented equilibrium partitioning between the solution and the solid phase. The derived value of DRa is one order of magnitude larger than that of DBa despite the larger ionic radius of Ra. This indicates that compatibility of ionic radius is not a dominant parameter for preferential incorporation of Ra and Ba in calcite.

Zarga Y. et al. Study of calcium carbonate and sulfate co-precipitation // Chemical Engineering Science. 2013. Vol. 96. P. 33–41.

Co-precipitation of mineral based salts in scaling is still not well understood and/or thermodynamically well defined in the water industry. This study focuses on investigating calcium carbonate (CaCO3) and sulfate mixed precipitation in scaling which is commonly observed in industrial water treatment processes including seawater desalination either by thermal-based or membrane-based processes. Co-precipitation kinetics were studied carefully by monitoring several parameters simultaneously measured, including: pH, calcium and alkalinity concentrations as well as quartz microbalance responses. The CaCO3 germination in mixed precipitation was found to be different than that of simple precipitation. Indeed, the co-precipitation of CaCO3 germination time was not anymore related to supersaturation as in a simple homogenous precipitation, but was significantly reduced when the gypsum crystals appeared first. On the other hand, the calcium sulfate crystals appear to reduce the energetic barrier of CaCO3 nucleation and lead to its precipitation by activating heterogeneous germination. However, the presence of CaCO3 crystals does not seem to have any significant effect on gypsum precipitation. IR spectroscopy and the Scanning Electronic Microscopy (SEM) were used to identify the nature of scales structures. Gypsum was found to be the dominant precipitate while calcite and especially vaterite were found at lower proportions. These analyses showed also that gypsum crystals promote calcite crystallization to the detriment of other forms.

Аллахвердов Г.Р., Невинчан О.М., Санду Р.А. Сокристаллизация неорганических веществ с неизоморфными примесями // Химическая промышленность сегодня. 2013. № 12. С. 3-5.

Предлагается метод расчета коэффициентов сокристаллизации неизоморфных неорганических соединений из водных растворов на основе использования свойств растворов чистого примесного компонента.

Богданова В.А., Вязенова И.А., Малушко О.В., Таранушич В.А. Направленное модифицирование свойств нитрата аммония железосодержащими солями // Научный альманах. 2015. №10-3(12). С. 39-42.

Исследования образцов нитрата аммония с железосодержащими добавками в количестве 1 и 3%, полученные методами механического смешения и изотермической сокристаллизации из водного раствора при температуре кипения позволили сделать вывод о том, что при использовании 3% добавок K 3[Fe(CN) 6] и K 4[Fe(CN) 6]_3Н 2О и способа введения - сокристаллизация из водного раствора при температуре кипения, можно получить фазостабильные образцы при одновременном снижении температуры начала разложения.

Велешко И.Е., Кулюхин С.А. Изучение поведения микроколичеств Cd и Zn в процессах сорбции и соосаждения в растворах тетрагидрофурана // Радиохимия. 2005. Т. 47. № 3. С. 261-264.

Изучена сорбция микроколичеств 109Cd и 65Zn на цеолитах NaX и NaA в присутствии восстановителей Ln2+ (Ln = Tm, Dy, Nd) из раствора тетрагидрофурана (ТГФ). Установлено, что в отличие от l37Cs+ микроколичества 109Cd и 65Zn, так же как и 85Sr2+, практически не сорбируются цеолитами и на ~99% остаются в растворе. При этом коэффициенты распределения (Кd)109 Cd и 65Zn составляют ~0.3 и ~0.4 мл/г соответственно. Установлено, что при использовании в качестве восстановителя Тm2+ происходит его частичное окисление в растворе до Тm3+ с образованием осадка состава ТmI3·ЗТГФ. Исследование сокристаллизации микроколичеств 109Cd и 65Zn, а также 85Sr2+ с твердой фазой сольвата ТmI3·ЗТГФ в присутствии Тm2+ из растворов ТГФ позволило установить, что в отличие от 85Sr2+ микроколичества 109Cd и 65Zn сокристаллизуются с твердой фазой сольвата. Найдено, что коэффициенты сокристаллизации (D) для 109Cd и 65Zn зависят от отношения Tm3+/Tm2+ в растворе и возрастают с его увеличением. Сделано предположение, что 109Cd и 65Zn2+ в присутствии Тm2+ образуют ионы М+, которые быстро взаимодействуют с ионами М2+ с образованием димеров состава m23+ (М = Cd, Zn).

Ворохобин И.С., Вязенова И.А., Таранушич В.А. Взаимодействие нитрата аммония с хлоридом калия в водно-этанольной среде // Известия высших учебных заведений. Серия: Химия и химическая технология. 2014. Т. 57. № 2. С. 30-33.

В статье приведены результаты исследования физико-химических свойств формируемых твердых фаз системы нитрат аммония - хлорид калия - вода при замене части растворителя на этанол. Показано, что введение органической фазы приводит к изменению состава и закономерностей формирования кристаллической структуры осадка.

Ворохобин И.С., Вязенова И.А., Таранушич В.А. Технология получения фазостабилизированного нитрата аммония // Известия высших учебных заведений. Северо-Кавказский регион. Серия: Технические науки. 2012. № 5. С. 102-105.

Работа посвящена исследованию технологических приемов сокристаллизации нитрата аммония с хлоридом калия (из расплава НА, из водного раствора при температуре кипения, из водного раствора при 25 оС в равновесных условиях) с целью получения фазостабильного окислителя газогенерирующих составов разного назначения, в том числе для автомобильных мешков безопасности. В результате проведенного исследования установлено, что метод равновесной изотермической сокристаллизации при 25 оС позволяет получить фазостабильный окислитель на основе нитрата аммония с минимальным содержанием добавки - 6 % хлорида калия. Методами физико-химического анализа (дифференциально-термического, ИК - спектроскопии, рентгенофазового) показано, что полученный результат достигнут за счет равномерного распределения добавки и образования плотной упаковки кристалла.

Ворохобин И.С., Вязенова И.А., Таранушич В.А. Физико-химический анализ системы NH4NO3 - KNO3 - Н2О при 25 0С // Инженерный вестник Дона. 2014. Т. 28. № 1. С. 60.

В статье представлены результаты исследования физико-химических свойств водной системы нитрат аммония - нитрат калия при 25о С. Анализ литературных данных показал, что однозначного мнения о составе твердых фаз нет: идентифицированы двойные соли различного состава, твердые растворы, эвтектики, поэтому представляло интерес уточнить вид и свойства формируемых структур. Методами дифференциально-термического и рентгено-фазового анализов установлено, что равновесная твердая фаза исследованной системы представляет собой два вида твердых растворов: на основе кристаллической решетки III фазы нитрата аммония (при содержании нитрата калия до 20 %) и на основе ромбической сингонии нитрата калия (при содержании нитрата калия более 80 %), параметры кристаллических ячеек образующихся фаз подчиняются правилу Вегарда. Образец нитрата аммония с содержанием нитрата калия более 12 % обладает фазовой стабильностью в диапазоне температур от минус 50 до плюс 100о С. Установлено, что наблюдается разрыв в смесимости компонентов в интервале концентраций нитрата калия от 30 до 80 %.

Крот Н.Н., Бессонов А.А., Чарушникова И.А., Григорьев М.С., Макаренков В.И. Синтез новых кристаллических соединений PU(V) из растворов. IV. ДВОЙНЫЕ МАЛОНАТЫ СОСТАВА СО(NН3)6[РUО2СЗН2О4]2А·NH2О, А = NO3, СLO4, С1 и ВR // Радиохимия. 2005. Т. 47. № 3. С. 224-227.

Добавлением небольшого избытка ионов Co(NH3)63+ к свежеприготовленным нейтральным малонатным растворам Pu(V) получены новые кристаллические соединения состава Co(NH3)6[PuO2L]2A·nH2O, где L = С3Н2О4 и А = NO3, С1О4, С1 и Вr. Они достаточно устойчивы при хранении на воздухе и изо-структурны с соответствующими соединениями Np(V). Изучено термическое поведение и измерены ИК спектры синтезированных соединений.

Кулюхин С.А. и др. Сокристаллизация микроколичеств 137Cs, 90Sr и 90Y с твердой фазой смешанного ферроцианида калия и неодима из водных растворов // Радиохимия. 2009. Т. 51. № 1. С. 36-39.

Исследована сокристаллизация микроколичеств 137Cs, 90Sr и 90Y с твердой фазой смешанного ферроцианида калия и неодима в зависимости от отношения K4[Fe(CN)6] : Nd(NO3)3 в водном растворе. Показано, что при отношении K4[Fe(CN)6] : Nd(NO3)3 > 2 все исследуемые радионуклиды практически количественно (96-99%) сокристаллизуются с твердой матрицей KND[Fe(CN)6]-4Н2O. Коэффициенты сокристаллизации D, рассчитанные по уравнению Гендерсона-Кречека, превышают 103. Изучено выщелачивание 137Cs и 152Eu из твердой матрицы К(137Сs)Nd(152Eu)[Fe(CN)6]-4Н2O водой, а также растворами 0.1 и 1.0 моль/л HN03 и 4.0 моль/л K0H.

Кулюхин С.А., Коновалова Н.А. и др. Соосаждение микроколичеств 137CS И 85SR С [NA(18-КPAYН-6)]BPH4 из нейтральных и щелочных растворов // Радиохимия. 2005. Т. 47. № 3. С. 257-260.

Изучено соосаждение 137Cs и 85Sr с твердой фазой [Nа(18-краун-6)]ВРh4 из водных, водно-этанольных и щелочных растворов. Показано, что 137Cs и 85Sr сокристаллизуются с твердой фазой [Na(18-кpayн-6)]BPh4 из водных и водно-этанольных растворов. Коэффициенты сокристаллизации D 137Cs и 85Sr для водных растворов равны 2.6±0.5 и 3.3 + 0.3 соответственно. В случае водно-этанольных растворов коэффициенты сокристаллизации D 137Cs и 85Sr с твердой фазой [Na(18-кpayн-6)]BPh4 равны 4.4±0.5 и 3.4±0.4 соответственно. В случае растворов 0.1 и 1 моль/л NaOH радионуклиды 137Cs и 85Sr переходят в твердую фазу комплекса [Na(18-кpayн-6)]BPh4 соответственно на 54 -74 и 37-51% в зависимости от количества полиэфира 18-краун-6, введенного в систему.

Михеева Н.Б., Мелихов И.В., Кулюхина С.А. Процессы сокристаллизации в исследованиях физико-химических свойств радиоактивных элементов в различных средах // Радиохимия. 2007. Т. 49. № 6. С. 481-490.

Процессы сокристаллизации широко распространены в природе и находят применение в химической технологии. В радиохимии они стали использоваться в конце XIX-начале XX столетий благодаря работам М. Кюри, О. Хана, В. Г. Хлопина и его учеников. Ими были установлены законы изоморфной сокристаллизации с участием микроколичеств радиоактивных элементов. Однако проблема образования аномальных смешанных кристаллов оставалась невыясненной. Существенный вклад в развитие этой проблемы был внесен А. Н. Киргинцевым. Благодаря его работам и последующим исследованиям других ученых стало возможным делать обоснованный вывод о заряде ионов сокристаллизующихся микрокомпонентов. Использование процессов сокристаллизации позволило установить важнейшие физико-химические свойства актинидов, недоступных в весовых количествах

Мишина Н.Е. и др. Исследование соосаждения нитратов бария и стронция при кристаллизации из растворов азотной кислоты и модельного высокоактивного рафината Пурекс-процесса // Радиохимия. 2015. Т. 57. № 5. С. 430-437.

Методами рентгенофазового анализа, химического анализа и ИК спектроскопии показано образование твердых растворов нитратов бария и стронция при осаждении из растворов HNO 3, La(NO 3) 3 и их смесей. Твердые растворы Ba(NO 3) 2 и Sr(NO 3) 2 в системе с водой образуются из насыщенных растворов при температуре 25°С и мольном соотношении Ba(NO 3) 2 : Sr(NO 3) 2 < 10. Истинное соосаждение в широком диапазоне составов в растворах HNO 3 наступает при достижении концентрации суммарного нитрат-иона (?NO 3 -) порядка 5 моль/л и выше. В растворах La(NO 3) 3 соосаждение происходит при ?NO 3 - ? 6.5 моль/л. При этом концентрация Sr(NO 3) 2 не опускается ниже его растворимости. Наблюдается образование твердого раствора из воды при ?NO 3 - < 5 моль/л в области концентраций Sr(NO 3) 2 ниже его растворимости, что свидетельствует о различии механизмов сокристаллизации в нейтральной и кислой областях. Кристаллографическое исследование осадка, полученного из смешанного раствора, содержащего одновременно нитраты бария и стронция на фоне 1 моль/л La(NO 3) 3 и 2 моль/л HNO 3, показало, что выпадающие кристаллы окутаны оболочкой некристаллического характера, представляющей собой, возможно, слой адсорбированной HNO 3, выделившейся при кристаллизации. На ИК спектре такого осадка выявлено наличие полосы, характерной для молекулярной HNO 3 в неводных средах, что, по-видимому, свидетельствует об образовании аддукта.

Мишина Н.Е. и др. Исследование соосаждения нитратов бария и стронция при кристаллизации из растворов азотной кислоты и модельного высокоактивного рафината Пурекс-процесса // Радиохимия. 2015. Т. 57. № 5. С. 430-437.

Методами рентгенофазового анализа, химического анализа и ИК спектроскопии показано образование твердых растворов нитратов бария и стронция при осаждении из растворов HNO 3, La(NO 3) 3 и их смесей. Твердые растворы Ba(NO 3) 2 и Sr(NO 3) 2 в системе с водой образуются из насыщенных растворов при температуре 25°С и мольном соотношении Ba(NO 3) 2 : Sr(NO 3) 2 < 10. Истинное соосаждение в широком диапазоне составов в растворах HNO 3 наступает при достижении концентрации суммарного нитрат-иона (?NO 3 -) порядка 5 моль/л и выше. В растворах La(NO 3) 3 соосаждение происходит при ?NO 3 - ? 6.5 моль/л. При этом концентрация Sr(NO 3) 2 не опускается ниже его растворимости. Наблюдается образование твердого раствора из воды при ?NO 3 - < 5 моль/л в области концентраций Sr(NO 3) 2 ниже его растворимости, что свидетельствует о различии механизмов сокристаллизации в нейтральной и кислой областях. Кристаллографическое исследование осадка, полученного из смешанного раствора, содержащего одновременно нитраты бария и стронция на фоне 1 моль/л La(NO 3) 3 и 2 моль/л HNO 3, показало, что выпадающие кристаллы окутаны оболочкой некристаллического характера, представляющей собой, возможно, слой адсорбированной HNO 3, выделившейся при кристаллизации. На ИК спектре такого осадка выявлено наличие полосы, характерной для молекулярной HNO 3 в неводных средах, что, по-видимому, свидетельствует об образовании аддукта.

Пьянкова Л.А., Пунин Ю.О., Штукенберг А.Г. Аномальная оптика и дефектность гетерофазных кристаллов NH4Cl: Mn2+ И NH4Cl: Си2+ // Вестник Санкт-Петербургского Университета. Серия 7. Геология. География. 2009. № 1. С. 52-61.

Экспериментально изучены системы NH4Cl-MnCl2-H2O-CONH3 и NН4С1-СuС12-Н2O-CONH3 и образующиеся в них гетерофазные кристаллы NH4C1:Mn2+ и NH4Cl:Си2+. Обнаружено, что примеси Сu2+ и Mn2+ интенсивно захватываются растущими кристаллами хлористого аммония до 7 вес.% при коэффициенте захвата примеси близким к 1. Захват примесей меди и марганца вызывает в кристаллах NH4C1 высокие внутренние напряжения (до 6.106 и 4.109 Па, соответственно), которые приводят к аномальному двупреломлению, расщеплению, блочности, двойникованию и растрескиванию кристаллов NH4Cl. Ключевые слова: аномальная оптика, дефекты, примеси Библиогр. 14 назв. Ил. 7. Табл. 1.

Таусон В.Л., Смагунов Н.В., Липко С.В. ОБ Использовании коэффициентов сокристаллизации изоморфных примесей для определения концентраций элементов в рудоносных растворах (на примере Mn/Fe -отношения в магнетите) // Геология и геофизика. 2015. Т. 56. № 8. С. 1441-1447.

В серии гидротермальных ростовых экспериментов с внутренним пробоотбором при 450 и 500 °С и давлении 100 МПа (1 кбар) определен коэффициент сокристаллизации Mn и Fe в кристаллах магнетита. Он мало зависит от температуры в изученной области и постоянен в широком интервале отношений Mn/Fe. Это дает основание для использования состава магнетита для оценки отношения Mn/Fe в равновесном с ним флюиде: (Mn/Fe) aq ? 100 (Mn/Fe) mt. Поскольку Mn нередко является макрокомпонентом флюида и микрокомпонентом в магнетите, локальный анализ включений на Mn сделает возможным определение Fe даже в минералах железа, что позволит, зная коэффициенты сокристаллизации D Me/ Fe, получить оценки концентраций других рудных металлов. При низких содержаниях Mn (< 0.01-0.02 %) для мелких кристаллов (< 0.1-0.2 мм) необходимо учитывать эффект фракционирования Mn в поверхностную неавтономную фазу, где его содержание может достигать целых процентов. Сравнение с полученными ранее данными по распределению Mn в системе магнетит-пирит-пирротин-гринокит-гидротермальный раствор позволяет заключить, что величина D Mn/ Fe сохраняется в присутствии в системе серы и сульфидов. Ввиду низкого значения этого коэффициента осаждение магнетита, в котором Mn обнаруживает совместимость, не может кардинально повлиять на отношение Mn/Fe в растворе. Тем более это нереально для пирротина и пирита, в которых Mn не является совместимой примесью. Наиболее вероятным механизмом перехода Mn в твердую фазу является кристаллизация при более низких температурах FeOOH, что косвенно подтверждается сильным фракционированием Mn в оксигидроксидную неавтономную фазу на поверхности кристаллов магнетита. Представлены соображения, указывающие на необходимость более строгого обоснования «нового Fe/Mn геотермометра для гидротермальных систем».

Теплов Г.В., Попок В.Н. Сокристаллизаты CL-20 и HMX c некоторыми полярными растворителями, содержащими карбонильную или эфирную группы // Ползуновский вестник. 2014. № 3. С. 114-117.

В работе получены и описаны новые сокристаллизаты на основе полициклического нитрамина CL-20 с полярными растворителями, содержащими карбонильную (N,N- диметилацетамид и N-метилпирролидон) или эфирную группы (тетрагидрофуран и диэтиленгликоль). Изучены некоторые физико-химические и взрывчатые свойства полученных сокристаллизатов.

Фомина И.Г. и др. Карбоксилатные кластеры с кубаноподобным остовом M 4O 4: пивалатный сокристаллизат с атомами Co II и Ni II // Известия Академии Наук. Серия химическая. 2010. № 4. С. 685.

В результате взаимодействия биядерных пивалатных комплексов M 2(?-H 2O)(?-Piv) 2(Piv) 2(HPiv) 4 (M = Co (1), Ni (2), Piv - - анион пивалиновой кислоты, декан, 174 °С, соотношение реагентов 1 : 1) и последующей обработки сухого продукта термической реакции метанолом выделены кристаллы нового продукта сокристаллизации молекул, имеющих гетерометаллический кубаноподобный остов M 4(Co,Ni)O 4. Согласно данным РСА, магнитных измерений, атомно-эмиссионного анализа с индуктивно-связанной плазмой (ICP) и исследований продуктов твердофазного термического разложения выделенный продукт сокристаллизации соответствует общей формуле [Co 1.6Ni 2.4(? 3-OMe) 4(? 2-Piv) 2(? 2-Piv) 2(MeОН) 4]•4MeОН (3•4MeOH). Термолиз кристаллов сольвата 3•4MeOH имеет деструктивный характер и сопровождается внутримолекулярным редокс-процессом. Конечными твердыми продуктами разложения 3•4MeOH в атмосфере аргона является смесь металлического Ni и оксида СоО, тогда как на воздухе образуется смесь фаз NiO, Со 3О 4 и NiСо 2О 4.

Штукенберг А.Г., Пунин Ю.О., Азимов П.Я. Кристаллизация в системах «твердый раствор-водный раствор»: термодинамика и кинетические эффекты // Кристаллография. 2010. Т. 55. № 2. С. 360-374.

Предлагается новый феноменологический подход к описанию кинетики кристаллизации в бинарных системах “твердый раствор-водный раствор”. В рамках данного подхода проводится рассмотрение фазовых диаграмм, равновесий и квазиравновесий. На этой основе обсуждается кинетика кристаллизации вблизи истинного равновесия и особенности кристаллизации при больших отклонениях от равновесия. Особое место уделяется возможным взаимодействиям раствора с помещенным в него затравочным кристаллом. В частности, рассматриваются взаимодействия, приводящие к росту или растворению затравочного кристалла, а также к возможным обменным или метасоматическим реакциям. Кроме того, проводится анализ влияния возникающих напряжений несоответствия на скорость роста и состав нарастающего материала.

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