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The use of accelerated carbonation technology in combination with a granulation process was employed to produce aggregates from a variety of industrial wastes, which included municipal solid waste incineration fly ash and air pollution control residue, oil shale ash, cement kiln dust, and quarry fines that have been produced in Estonia. Focusing mainly on the effects produced by the content of municipal solid waste incineration ash in the admixtures, the granule compositions were varied in order to tailor granule properties on the basis of CO2 uptake, strength development, leaching behaviour, microstructure, and morphology. All the steps involved in the accelerated carbonation technology granulation process, from mixing with additives to granulation and carbonation treatment, were carried out in the same apparatus – an Eirich EL1 intensive mixer/granulator. The amount of CO2 that was bound ranged from 23 to 108 kg per tonne of waste. The granules that included the optimised mixture of municipal solid waste incineration air pollution control residue, oil shale ash, cement kiln dust, and ordinary Portland cement were characterised by the highest compressive strength (4.03 MPa) and water durability for the size range of 4–10 mm. In addition, the process was found to be effective in reducing alkalinity (pH < 11.5) and immobilising heavy metals (especially zinc) and chloride. The composition and properties of the respective waste materials and mechanisms associated with the characteristics of the resulting granules were also addressed.

Thermal behaviour of shelly Estonian phosphorite ores from Iru, Toolse, Ulgase deposits and their concentrates have been studied. The phosphorus-bearing mineral in Estonian phosphate ore is fluorcarbonate apatite (francolite), originated from brachiopod Obolus apollinis shells that makes it different from all other sedimentary phosphate ores. The experiments on a Setaram Labsys Evo 1600 thermoanalyzer coupled with Pfeiffer Omnistar Mass Spectrometer for evolved gases analysis were carried out under non-isothermal condition at the heating rate of 10 °C min−1 up to 1200 °C in an oxidizing and inert atmosphere containing 79% of Ar and 21% of O2 or 100% Ar, respectively. The results obtained indicated the complicated character of transformations occurring at thermal treatment of Estonian phosphorites and certain differences depending on the mineralogical composition of sample and gaseous environment. The changes in francolite structure, probable substitution of sulphur additionally to carbonate, were studied by FTIR and XRD. The oxygen in gaseous atmosphere suppresses the liberation of carbonate and sulphate from the structure of francolite. The character of CO2 and SO2 release at heating depending on the atmosphere composition was explained. The impact of thermal treatment of phosphorite on the P2O5, CaO and SO4−2 solubility in 2% citric acid solution and on the particles pore volume, as well as their dependence on each other, was also studied.

Graptolite–argillites (black shales) are studied as potential source of different metals. In the processing technologies of graptolite–argillites, a preceding thermal treatment is often applied. In this study, the thermal behavior of Estonian graptolite–argillite (GA) samples from Toolse, Sillamäe and Pakri areas were studied using a Setaram Labsys Evo 1600 thermoanalyzer coupled with the Pfeiffer OmniStar Mass Spectrometer. The products of thermal treatment were studied by XRD, FTIR, and SEM analytical methods. The experiments were carried out under non-isothermal conditions of up to 1200 °C at different heating rates in the atmosphere containing 79% Ar and 21% O2. The differential isoconversional Friedman method was applied for calculating the kinetic parameters. All studied GA samples are characterized with high content of orthoclase (between 38.0 and 57.3%) and quartz (between 23.8 and 35.5%), and with lower content of muscovite, jarosite, pyrite, etc. The content of organic carbon in GA samples studied varied between 7.3 and 14.2%. The results indicated that, up to 200 °C, the emission of hygroscopic and physically bound water takes place. Between 200 °C and 500–550 °C, this is followed by thermo-oxidative decomposition of organic matter. The first step of thermo-oxidation of pyrite with the emission of water, carbon and sulphur dioxide, nitrogen oxides, and different hydrocarbon fragments indicated the complicated composition of organic matter. At higher temperatures, between 550 °C and 900 °C, the transformations continued by dehydroxylation processes in clay minerals, and the decomposition of jarosite and carbonates took place. At temperatures above 1000–1050 °C, a slow increase in the emission of sulphur dioxide followed, indicating the beginning of the second step of thermo-oxidative decomposition of pyrite, which was not completed for temperatures of up to 1000 °C. Kinetic calculations prove the complicated mechanism of thermal decomposition of GA samples: for Pakri GA samples, it occurs in two steps, and for Silllamäe and Toolse GA samples, it occurs in three steps. Preliminary tests for the estimation of the influence of pre-roasting of GA samples on the solubility of different elements contained in GA at the following leaching in sulphuric acid is based on Toolse GA sample.

ZnO is an important inorganic material for numerous applications. Different physical and chemical methods have been applied to deposit ZnO. Spray pyrolysis method being simple, rapid and low-cost is amongst the many options and has been chosen for this study. Fabrication of ZnO nanorods crystals by chemical spray pyrolysis was performed using an acidic solution of ZnCl2 1 or a basic ammonia-containing solution of ZnCl2 2. All layers were studied using X-ray diffractometry and Scanning Electron Microscopy. The formation of ZnO nanorods from 2 appeared at 450 °C, whereas spraying acidic solution 1 yielded ZnO nanorods like morphology at 550 °C. Thermal decomposition of precursors for ZnO layers prepared by de-watering of acidic aqueous solution of ZnCl2 with pH = 3 (1) and basic solution of ZnCl2 and NH4OH with pH = 10 (2) was monitored by simultaneous thermogravimetric and differential thermal analysis (TG/DTA) in air coupled online with evolved gas analyses by Fourier transformed infrared spectroscopy (FTIR). The precursor (1) is ZnCl2 *nH2O; the precursor (2) is a mixture of (NH4)3(ZnCl4)Cl, Zn(NH3)2Cl2, NH4Cl(NH3)3 and Zn(OH)2 phases. The thermal decomposition of (1) and (2) in the temperature range of 30–700 °C consists of two steps with total mass losses of 86.2% and 93.8%, respectively. The main evolved gases from (1) are H2O and HCl, whereas the main evolved gases from (2) are H2O, NOx and NH3. Degradation of (1) and (2) is completed by 670 and 620 °C, respectively. The final decomposition product of (1) and (2) at 700 °C is ZnO. This study shows that the use of basic solutions enables to decrease the temperature of ZnO formation and the deposition temperature of ZnO nanorods layers.

Phosphorus is an essential and non-substitutable element for the cellular processes of all living organisms. The main source of phosphorus in the biosphere is phosphate rock. With more than 700 Mt phosphate rock, Estonia holds the largest sedimentary phosphate rock deposits in the European Union. Estonian phosphate rock is particularly outstanding due to its remarkably low content of hazardous heavy metals such as Cadmium (&lt, 5 ppm) and trace elements of Uranium (&lt, 50 ppm). It is also a reliable source of valuable elements such as rear earth elements (REEs). The aim of this study was to investigate the distribution of the main minerals (apatite and quartz) between slimes, tailings, and concentrates that formed at the froth flotation of Estonian phosphate rock with the up-to-date level of know-how and techniques. Subsequently, the relationship between the obtained grades and recovery levels in concentrates was determined based on the collector dosage and flotation duration. It was observed that the fine fraction of the tailings contains 17.9&ndash, 33.49 wt% P2O5 that can be added to the final product. Moreover, it was found that, with the lower dosage of the collector, the extended flotation time does not influence the phosphate grade and a high amount of quartz remains in the concentrates. It was also shown that, by raising the collector dosage and setting the flotation time, an adequate grade (&gt, 32 wt% P2O5) and recovery (up to 98%) can be gained. The results showed that Estonian phosphate rock can be beneficiated to produce a high-quality concentrate at high recovery levels by modifying the main flotation parameters depending on the properties of the ore.

Estonia holds the largest unexploited sedimentary phosphate rock reserves in the EU. Compared to other sedimentary and also igneous phosphate rocks the Estonian phosphorite is particularly outstanding by its remarkably low Cd (1–5 ppm) and trace U content (~50 ppm) and also contains valuable elements such as rare earth elements (REEs), which could be used in important high-technologies in the future. In this paper beneficiation by reverse flotation of the silicates for three types of Estonian phosphorite ores was investigated. The apatite concentrates with grades of over 33 wt% P2O5 at recoveries of 84.8 to 89.2% were achieved. The concentrates had low MgO contents and grades of FeO ranged from 1.29 up to 2.54 wt%. The study gives an overview of the specifics of enrichment of Estonian shelly phosphorite ores, provides a ground for future in-depth and pilot-scale experiments to find proper solutions for the Estonian phosphorite processing and will be applied in the feasibility studies of the phosphorite industrialization.

Pure Ca hydroxyapatites (CaHAp) and Na-, Mg-, Zn- and Sr-substituted precipitated apatites were characterized by X-ray diffraction analysis, Fourier transformed infrared spectroscopy and element, chemical, and TG/DTA–EGA–MS analysis at their heating up to 1200 °C in Ar atmosphere. The evolvement of H2O, CO2, NH3, and NxOy was followed by mass spectroscopy (MS). Comparison of thermal behavior of pure CaHAps and cation-substituted apatites indicates that the exact temperatures of the release of gases (thermal stability) depend strongly on the chemical composition and crystallinity of sample. The presence of nitrogen species was detected by TA–MS in all precipitated apatites, and its content (0.01–1 %) depends on the synthesis conditions, the washing profoundness as well as on the cationic composition of apatite.

International audience; Motivated by the role of copper ions in biological processes the aim of this study was to elucidate the impact of copper ions bound to hydroxyapatite on l-serine (l-Ser) and O-phospho-l-serine (O-Ph-l-Ser) adsorption at different acidity of aqueous solutions. The adsorption phenomenon was studied by FTIR, UV, and AA spectroscopy, XRD and thermal analysis methods together with the evolved gases analysis taking into consideration the ionic state of the amino acids as well as the apatite surface state, which are tightly correlated with the solution pH. In acidic solution, the main process involves apatite dissolution releasing calcium and copper ions. At pH > 5 the complexation of amino acids with Ca2+ or Cu2+ ions is more important leading also to the release of cations. The ability of copper ions to form water soluble complexes with l-Ser and O-Ph-l-Ser leads to an important loss of these ions, while calcium release is very low at this pH. Therefore, the use of copper ions substituting calcium in the apatite structure to enhance the ability of amino acids adsorption on the apatite surface seems problematic even at pH > 5.

Thermal decomposition of precursors for SnS thin films obtained by drying aqueous solutions of SnCl2 and SC(NH2)2 in the Sn:S molar ratios of 1:1 (1) and 1:8 (2) was monitored by simultaneous thermogravimetry/differential thermal analysis (TG/DTA) measurements in the dynamic 80 % Ar + 20 % O2 atmosphere. The evolved gaseous species from 1 were recorded by simultaneous thermogravimetry/differential thermal analysis/evolved gas analysis–mass spectrometry (TG/DTA/EGA-MS) measurements. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the dried precursors and products of the thermal decomposition. The precursor 1 is a complex compound, Sn(tu)Cl2, while 2 consists of Sn2(tu)5Cl4·H2O and noncomplexed thiourea. The thermal degradation of 1 and 2 in the temperature range of 30–700 °C consists of four steps with a total mass loss of 68.0 and 84.5 %, respectively. According to XRD, the solid decomposition products at 210 °C of 1 are SnS2, (NH4)2SnCl6 and C(NH2)3SnCl3, and of 2 are SnS2, SnS, NH4Cl and (NH4)2SnCl6. Decomposition of 1 and 2 is completed by 550 and 570 °C, respectively. The final decomposition product of 1 and 2 at 700 °C is SnO2. This study shows that the excess of thiourea in the spray solution, compared to that required for the formation of the intermediate tin complex compounds, suppresses the formation of tin oxide phase and depresses the loss of tin species from the system.

In this study, investigation of the Ca–P–O, Ca:Zn–P–O, Ca:Na–P–O, and Ca:Zn:Na–P–O precursor gels prepared using EDTA as complexing agent and slightly different starting materials was performed. For this purpose, thermal decomposition of the gels was studied by TG/DTA-EGA/MS with following evolvement of H2O, CO2, NH3, and NOx gases. Besides, thermal decomposition products were characterized by Fourier transform infrared spectroscopy, X-ray diffraction analysis, and scanning electron microscopy. It was demonstrated that thermal decomposition of Ca–P–O acetate and Ca:Zn–P–O, Ca:Zn:Na–P–O acetate-nitrate gels is different. Thus, the results of thermal decomposition of Ca:Zn–P–O and Ca:Zn:Na–P–O gels showed that Zn and Na additives accelerate decomposition of the gels. In addition, Na substitution at Ca sites creates conditions for the formation of the orthophosphate composites at lower temperatures.

The phase transitions and chemical reactions in the formation process of Cu2ZnSnSe4 (CZTSe) from CuSe, SnSe, and ZnSe in the presence of KI were studied using the DTA method for the determination of thermal effects. XRD and Raman spectroscopy were performed for the phase analysis in samples after heating them for prolonged time to several degrees of temperatures higher than peak-top temperatures of DTA effects in heating and cooling curves. The chemical pathways of the CZTSe formation before and during the melting of KI were clarified. The reaction enthalpies were determined using pure KI as a substance for the calibration of enthalpy values. In the mixtures, the melting of KI is always accompanied by some dissolution of the precursor compounds and lowering of the melting temperature in comparison with pure KI. The initiator of the process of the partial CZTSe formation at around 400 °C is elemental Se. The CZTSe formation of binary precursors in liquid phase of KI takes place with the experimentally determined enthalpy of −36 ± 2 kJ mol−1. The heat of fusion of formed CZTSe is 4 kJ mol−1 at 788 °C.

International audience; We describe herein the use of Calcium, Barium and Strontium hydroxyapatites (CaHAp, BaHAp and SrHAp) as well as CaHAp containing Magnesium, Copper, Zinc and Palladium (MgHAp, CuHAp, ZnHAp and PdHAp) as catalysts in the Biginelli reaction. The efficiency of CaHAp and SrHAp is very low, leading to the expected 3,4-dihydropyrimidin-2(1H)-one in poor yields. Mixed Ba 5 Sr 5 HAp and Ba 10 HAp show interesting catalytic properties, especially Ba 10 HAp leading to pure isolated reaction products in good yields. The use of modified CaHAp seems to be of interest in regard to the yield obtained. Nevertheless the release of Mg, Cu, Zn and Pd ions in the solution during the catalytic process makes the use of such modified apatites less effective.

The present study deals with chemical reactions and enthalpies during the synthesis of Cu2ZnSnSe4 (CZTSe) from CuSe, SnSe, and ZnSe in molten NaI as flux material in closed degassed ampoules. Differential thermal analysis (DTA) at heating rates 5 °C min−1 and cooling rates 10 °C min−1 were used for the determination of temperatures of phase transitions and/or chemical reactions. XRD and Raman analyses confirmed that the formation of CZTSe starts already at 380 °C after the melting of Se that deliberates from the transformation of CuSe to Cu1.8Se, and the CZTSe formation process impedes to a great extent due to the presence of solid NaI. After the melting of NaI, the formation of CZTSe is completed. For the determination of enthalpy values, the calibration with pure NaI was performed. The thermal effects and enthalpies were compared with the available known thermodynamical values. The specific enthalpy of exothermic Cu2ZnSnSe4 formation at 661 °C in NaI −36 ± 3 kJ mol−1 was determined experimentally for the first time. Ternary compound Na2SnSe3 was formed during the synthesis process. NaI·2H2O, if present in NaI, was found to be a critical issue in the synthesis process of CZTSe monograin powders in molten NaI—it gave rise to the formation of oxygen-containing by-products Na2SeO4 and Na2Cu(OH)4. The complete dehydration of NaI·2H2O at T ≤ 70 °C in vacuum is necessary to avoid the formation of oxygen-containing compounds.

Nanosize Mg2+, Zn2+, Sr2+, and Na+ mono- and di-substituted calcium hydroxyapatites were synthesized using an aqueous precipitation route under controlled conditions. The chemical composition and the micro-structural features of the polycrystalline samples were characterized by chemical analysis, thermal analysis (TG/DTA) combined with MS for evolved gas analysis, FTIR and XRD spectroscopy as well as SEM. The correlations between chemical composition and the crystal morphology were elucidated.

Thermal decomposition of HAuCl4·3H2O and AgNO3, as precursors for Au and Ag nanoparticles, respectively, was monitored by coupled TG–DTA with TG/EGA–FTIR and EGA–MS techniques in a flowing 80 %Ar + 20 %O2 and Ar atmospheres in the temperature range of 30–600 °C. The intermediate and final products of thermal decomposition were analysed by ex situ XRD and FTIR techniques. The thermal degradation of HAuCl4·3H2O starts immediately after melting at 75 °C and takes place in three steps in the temperature range of 75–320 °C with total mass loss of 49.4 and 49.7 % in artificial air and Ar atmospheres, respectively. EGA by MS and FTIR revealed a simultaneous release of H2O and HCl in the temperature range of 75–235 °C. EGA by MS revealed a release of Cl2 at around 225 °C and in the interval of 250–320 °C. According to the XRD analysis, the main solid product in the end of the first decomposition step at 190 °C is AuCl3; in the end of the second decomposition step at 240 °C is AuCl and the final product at 320 °C is Au. The thermal decomposition of AgNO3 takes place in a single step in the temperature range of 360–515 °C with a total mass loss of 39.0 and 37.8 % in flowing artificial air and Ar atmospheres, respectively. According to EGA–MS and EGA–FTIR the main evolved gases are NO2, NO and O2. The final product of the thermal decomposition at 600 °C is Ag irrespective of the atmosphere.

The thermal decomposition of precursors for copper indium disulphide (CuInS2) thin films obtained by drying aqueous solutions of copper chloride (CuCl2), indium chloride (InCl3) and thiourea (SC(NH2)2) at the Cu:In:S molar ratios of 1:1:3 (1) and 1:1:6 (2) was monitored by simultaneous thermogravimetry /differential thermal analysis/ evolved gas analysis-mass spectrometry (TG/DTA/EGA-MS) measurements in a dynamic 80 %Ar + 20 %O2 atmosphere. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to characterise the dried precursors and products of the thermal decomposition. The precursors 1 and 2 are mixtures of copper and indium chloride thiourea complex compounds, whilst 1 can also contain unreacted InCl3. The thermal degradation of 1 and 2 in the temperature range of 30–800 °C consists of six steps with a total mass loss of 71.5 and 89.8 %, respectively. According to XRD, CuInS2 is formed below 300 °C. Decomposition of 1 and 2 is completed at 620 and 600 °C, respectively. The final decomposition product of 1 at 800 °C consists of a mixture of In2O3 and CuO phases, whilst 2 consists of In2O3, CuO and Cu2In2O5 phases. EGA by MS revealed the release of CS2, NH3, H2NCN and HNCS, which upon their oxidation also yield COS, SO2, HCN and CO2.

Effective removal of chromium(III) from waste waters e.g. in the leather industry is required due to continuously tightening environmental regulations, and several methods such as precipitation and adsorption are currently in use. Nevertheless, more efficient, straightforward and inexpensive methods are constantly being sought. The current study describes a novel method to separate chromium(III) from aqueous solutions based on the use of solid bisphosphonates with a P–C–P backbone. Five classes of bisphosphonates with different functional groups and alkyl chain lengths at the center carbon, in all 16 compounds, were prepared and their suitability for metal ion complexing as chelating agents was investigated. Two of the studied compounds, which were almost insoluble in water, were effective in removing chromium(III) quantitatively from aqueous solutions and real waste water samples of tanneries. The results obtained were also compared to the commercially available Diphonix® resin.

The Y-Zr-O precursors derived from an aqueous sol–gel synthesis have been applied for the preparation of yttria-stabilized zirconia (YSZ) powders and thin films on the corundum (Al2O3) substrate, using dip-coating technique. In this aqueous sol–gel synthesis route, citric acid as a complexing agent has been used for the preparation of stable Y-Zr-O nitrate–citrate sols and gels. Thermal decomposition of dried gels was studied by simultaneous TG/DTA/EGA-FTIR measurements in the dynamic 80%Ar + 20%O2 atmosphere. FTIR and X-ray diffraction analyses were used for the determination of phase purity of the end products obtained at 700, 800 and 900 °C. The morphological features of the prepared YSZ coatings and powders were evaluated using scanning electron microscopy.

The removal of Cd from aqueous solutions by hydroxyapatite (HAP) was investigated with and without EDTA being present. Batch experiments were carried out using synthetic hydroxyapatite with Ca/P 1. ...

High temperature processing is essential for the preparation of apatites for biomaterials, lighting, waste removal and other applications. This requires a good understanding of the thermal stability and transitions upon heating. The most widely used is hydroxyapatite (HAp), but increasing interest is being directed to fluorapatite (FAp) and chlorapatite (ClAp). The structural modifications for substitutions are discussed to understand the temperature processing range for the different apatites. This is based on a review of the literature from the past few decades, together with recent research results. Apatite thermal stability is mainly determined by the stoichiometry (Ca/P ratio and structural substitutions) and the gas composition during heating. Thermal stability is lowered the most by a substitution of calcium and phosphate, leading to loss in phase stability at temperatures less than 900 °C. The anions in the hexagonal axis, OH in HAp, F in FAp and Cl in ClAp are the last to leave upon heating, and prevention of the loss of these groups ensures high temperature stability. The information discussed here will assist in understanding the changes of apatites during heating in calcination, sintering, hydrothermal processing, plasma spraying, flame pyrolysis, and other high-temperature processes.

Thermal decomposition of precursors for In2S3 thin films obtained by drying aqueous solutions of InCl3 and SC(NH2)2 at the In:S molar ratios of 1:3 (1) and 1:6 (2) was monitored by simultaneous TG/DTA/EGA-FTIR measurements in the dynamic 80%Ar + 20%O2 atmosphere. XRD and FTIR were used to identify the dried precursors and products of the thermal decomposition. The precursors 1 and 2 are complex compounds, while in 2 free SC(NH2)2 is also present. The thermal degradation of 1 and 2 in the temperature range of 30–900 °C consists of four mass loss steps, the total mass loss being 89.1 and 78.5%, respectively. According to XRD, In2S3 is formed below 300 °C, crystalline In2.24(NCN)3 is detected only in 1 above 520 °C and In2O3 is the final decomposition product at 900 °C. The gaseous species evolved include CS2, NH3, H2NCN, HNCS, which upon oxidation yield also COS, SO2, HCN and CO2.

The effect of soluble humic substances (HUM) on Cd sorption and desorption on apatite in aqueous solutions is studied. Batch experiments were carried out using synthetic hydroxyapatite (HAp) and fluorapatite (FAp). Parallel experiments in distilled water, Cd2+, Ca2+, HUM, Cd2++HUM, Cd2++Ca2+ and Ca2++HUM solutions showed that the solubility of apatite did not increase in the initial pH range from 5 to 8 in the presence of dissolved HUM. Dissolved HUM were bound on apatite in suspensions. The pH of suspensions stabilised at 6.4–6.5 in water. The presence of soluble HUM did not change this. Cd uptake resulted in a reduction in pH. The amount of Cd bound on apatite was not changed by HUM, but HUM affected the desorption level of sorbed Cd2+.

Thermal decomposition of dried crystalline powder obtained from titanium(IV) bis(acetylacetonate) diisopropoxide (75% solution in 2-propanol) (1) was monitored by simultaneous TG/DTA, EGA-FTIR and EGA-MS measurements and the results were compared with those of amorphous powder obtained by gelling of acetylacetonate-modified titanium(IV) tetra-isopropoxide at molar ratio of 1:2 in boiling 2-methoxyethanol (2). Thermal degradation of 1 in the temperature range of 25–700°C consists of 5 steps with a total mass loss of 62.5%. EGA by FTIR and MS revealed the release of H2O below 120°C; followed by an intensive evolution of acetylacetone around 245°C. The release of acetone and acetic acid occurs up to 270°C and that of CO and CO2 up to 530°C.

In this study the formation of chromium substituted YBa2Cu4O8 (Y-124) superconductors has been investigated by TG/DTA measurements. The YBa2(Cu1−xCrx)4O8 ceramics with nominal compositions of x=0.01, 0.03, 0.05, 0.10 and 0.20 have been prepared by an aqueous sol-gel method using aqueous mixtures of the corresponding metal acetates and nitrates. Homogeneous precursor gels were obtained by complexing metal ions with tartaric acid. To assist the interpretation of the results obtained the synthesis products were additionally characterized by X-ray powder diffraction (XRD) and resistivity measurements. It was determined that doping the YBa2Cu4O8 phase with chromium has a strong effect on the phase purity and superconducting properties of the synthesis products.

The reaction between phenyl phosphonic dichloride (C{sub 6}H{sub 5}P(O)Cl{sub 2}) and synthetic calcium hydroxy- and fluorapatite has been investigated. The presence of mono- or polymeric (C{sub 6}H{sub 5}PO) fragment bound to hydroxyapatite was evidenced by IR, and solid-state {sup 31}P NMR spectroscopy. X-ray powder analysis has shown that the apatitic structure remains unchanged during the reaction. In contrast, no reaction was found using fluorapatite. According to the results found for these two different apatites a mechanism was proposed for the formation of covalent P-O-P bonds as the result of a reaction between the C{sub 6}H{sub 5}P(O)Cl{sub 2} organic reagent and (HPO{sub 4}){sup -} and/or OH{sup -} ions of the hydroxyapatite. - Graphical abstract: Representation of the first step of the reaction between the phenyl phosphonic dichloride and the hydroxyl groups on the surface of the apatite, leading to covalent P-O-P bond with elimination of HCl.

Thermal decomposition of precursor xerogels for TiO2, obtained by gelling of acetylacetonate-modified titanium(IV) tetraisopropoxide (prepared at Ti-alkoxide:acetylacetone molar ratios of 1:1 (Ti-1) and 1:2 (Ti-2)) in boiling 2-methoxyethanol, was monitored by simultaneous TG/DTA/EGA-MS and EGA-FTIR measurements. Thermal degradation processes of Ti-1 and Ti-2 in the temperature range of 30–700°C consist of six mass loss steps, the total mass loss being 46.3% and 54.4%, respectively. EGA by FTIR and MS revealed release of H2O below 120°C; followed by evolution of acetone and acetic acid between approximately 100 and 320°C, and that of CO2 up to 560°C. Acetylacetone is evolved to a significant extent from sample Ti-2 at 120–200°C.

Aqueous sol–gel chemistry routes based on ammonium–hydrogen phosphate as the phosphorus precursor and calcium acetate monohydrate as source of calcium ions have been developed to prepare calcium hydroxyapatite samples with different morphological properties. In the sol–gel processes, an aqueous solutions of ethylene diamine tetra-acetic acid (EDTA) or tartaric acid (TA) as complexing agents were added to the reaction mixture. The monophasic Ca 10 (PO 4 ) 6 (OH) 2 samples were obtained by calcination of precursor gels for 5 h at 1000 °C. The phase transformations, composition and micro-structural features in the polycrystalline samples were studied by thermoanalytical methods (TGA/DTA), infrared spectroscopy (IR), X-ray powder diffraction analysis (XRD) and scanning electron microscopy (SEM). It was shown that adjusting the nature of complexing agent in the aqueous sol–gel processing can be used to control the morphology of the ceramic samples.

International audience; The oxidative Glaser–Hay coupling reaction of terminal alkynes is a very important reaction in organic chemistry to achieve the synthesis of diyne compounds. In general the reaction is performed under homogeneous conditions using Cu(I) or Cu(II) salts in the presence of a reagent such as tetramethylethylenediamine (TMEDA), which can bind to copper ions, an organic base and dioxygen. Although this reaction is known for a long time, the mechanism is still under discussion. Pursuing our investigations on the use of apatites as catalysts for organic reactions we highlight in this work how it is possible to catalyze the Glaser–Hay reaction under heterogeneous conditions using a Cu-modified hydroxyapatite (Cu–HAp). With several para-substituted phenyl-acetylenes and alkynols we show that Cu–HAp acts as catalyst for Csingle bondC coupling reactions leading to diyne derivatives in high yields without using auxiliary chelating molecules and organic bases. These heterogeneous conditions allow an easy recovery of the catalyst and simplify the purification work-up.

Thermal reactions in natural fluorapatite or fluorcarbonate apatite and ammonium sulfate mixtures with mole ratio 1:4 at calcination up to 500°C were studied by simultaneous thermogravimetry and FTIR analysis of the evolved gases. The composition of natural apatite has little impact on the release of NH3. Upon the evolution of NH3 nitrous oxides were found in minor amounts. The release of SO2 at temperatures above 400°C is more intensive and occurs at lower temperatures in the case of fluorapatite than of carbonate containing apatites. Evolution of CO2 starts at 250°C with maximum at 350-360°C.

Thermal decomposition of dried TiO2 gel, obtained by hydrolysing acetylacetonate-modified titanium(IV) isopropoxide, was monitored by simultaneous TG/DTA/EGA-FTIR measurements in dynamic air up to 900°C. XRD and FTIR were employed to identify the solid reaction products. Thermal degradation of the TiO2 gel consists of five distinct mass loss steps, the total mass loss being 43.8p. EGA by FTIR revealed the release of H2O below 120°C; followed by acetone, isopropyl acetate and 1-propanol around 200-300°C, and finally CO and CO2 up to 550°C. Highly exothermic reaction at 410-550°C is caused by the combustion of carbon residues. Crystalline TiO2-anatase is formed around 500°C and TiO2-rutile close to 800°C.

The thermal reactions in the mixtures of hydroxylapatite or fluorapatite and (NH4)2SO4up to 500°C were studied with the purpose of elaborating the conditions of obtaining calcium–ammonium cyclophosphate that could be used as fertilizer. Thermal analysis with a simultaneous FTIR analysis of the evolved gases as well as the analyses of chemical and phase composition of solid products were performed. The thermal changes in the mixtures could be divided into three steps: (1) decomposition of (NH4)2SO4and reactions of apatite with these products at 250–420°C, (2) calcium ammonium polyphosphate formation at 290–450°C, and (3) reaction of CaSO4with CaNH4P3O9at 320–500°C. Higher concentrations of NH3in the gas phase promote the formation of CaNH4P3O9and increase its stability. Calcination at temperatures above 350°C causes decomposition of CaNH4P3O9with a decrease in the content of water-soluble phosphorus and evolvement of SO2.

Optically active two-dimensional (2D) MIPS[Mn I I M I I I (C 2 O 4 ) 3 ] bimetallic networks with MIPS = 4-[4-methoxy-α-styryl]-N-isopentylpyridinium and M I I I = Cr, Co were obtained using as chiral inducing reagents the resolved (A)- or (A)-[M I I (C 2 O 4 ) 3 ] 3 - building blocks. The correlation of the natural circular dichroism (NCD) of these 2D networks with their UV-vis properties demonstrates that the [Mn I I M I I I (C 2 O 4 ) 3 ] - anionic network has a chiral matrix effect on the MIPS + cation: the choice of the configuration of the starting tris(oxalato)metallate(III) determines the helical conformation of the MIPS + cation. Such a conformation of the cation sharply contrasts with the perfectly planar geometry observed by X-ray diffraction in MIPSBr.

Calcium sulphate-apatites were synthesised by precipitation from aqueous solutions with different fluorine content and analyzed by chemical, x-ray diffraction (XRD), Raman, and Fourier transform infrared (FTIR) analyses. Their thermal stability was studied by differential scanning calorimetry (TG/DSC) and high-temperature XRD. It was established that the introduction of SO 4 2 m into apatite structure and the thermal changes depend on the fluorine content in the apatite structure. At temperatures above 600°;C the structure of apatite reorganizes and CaSO 4 forms a separate phase.

Effects of fluoride and carbonate substitutions in apatite (Ap) on Cd2+ sorption capacity from aqueous solutions (pH = 6) were examined on precipitated apatites by a batch method. Chemical, XRD, FTIR, BET and TEM analyses were used. The sorption of Cd2+ on Ap proceeds mainly by an ion exchange mechanism. The most important factor influencing Aps sorption capacity is the specific surface area. The amount of Cd2+ bound reaches 58 mmol/100 g Ap for hydroxyapatite, the increase in carbonate and fluoride content diminishes the sorption of Cd2+ to 5.5mmol/100g Ap. The removal of structural water from Ap has no significant effect on the Cd2+ sorption capacity.

The reaction of SO2 with synthetic apatites was studied by TG, XRD and IR analyses at 400-1000°C. Due to an interaction of apatite with SO2, destruction of apatite and formation of CaSO4 and diphosphate up to 750°C takes place. The further calcination leads to the formation of β-Ca3(PO4)2 and a part of the SO2 bound is lost again. The amount of SO2 bound with apatite at calcination depends on the substitution ((F- ↔ OH-, PO43- ↔ CO32-, Ca2+ ↔ Mg2+) in its structure.

Evolved gas analyses of model inorganic compounds and apatites are described. The measurements were performed on a system comprising a `thermochromatograph', with a low-volume thermal furnace, interfaced to a capillary gas chromatograph via a computer-controlled, pneumatic sample inlet device in the temperature region 70–600°C. The performance of this inherently simpler system is comparable to that of thermogravimetry but is superior in resolving possible reactions when similar materials are analysed.