Bibliographies thématiques / Hemihydrate de sulfate de calcium

Littérature scientifique sur le sujet « Hemihydrate de sulfate de calcium »

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Publié le 8 juillet 2023

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Articles de revues sur le sujet "Hemihydrate de sulfate de calcium"

1

MATSUI, Hiroshi, Kayoko AMITA, Genzo HASHIZUME, Gin-ya ADACHI et Jiro SHIOKAWA. « The formation of needlelike .ALPHA.-calcium sulfate hemihydrate from calcium sulfite hemihydrate. » NIPPON KAGAKU KAISHI, no 12 (1987) : 2279–85. http://dx.doi.org/10.1246/nikkashi.1987.2279.

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Liu, Xian Feng, Jia Hui Peng, Jian Xin Zhang, Ming Zheng Chen et Qian Dong. « Effect of Polycarboxylicacid Plasticizer on Characteristics of α-Calcium Sulfate Hemihydrate ». Applied Mechanics and Materials 423-426 (septembre 2013) : 1085–89. http://dx.doi.org/10.4028/www.scientific.net/amm.423-426.1085.

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Purpose: studied the mechanism of polycarboxylicacid plasticizing effect on α-calcium sulfate hemihydrate. Methods: the adsorbed amount was tested by ultraviolet visible absorption spectrum method, ζ potential was measured by micro-electrophoresis analysis, and the corresponding workability was studied. Results: firstly, polycarboxylicacid plasticizer was adsorbed on α-calcium sulfate hemihydrate by Van Der Waals force and the saturated adsorption quantity of polycarboxylicacid plasticizer (HC) was about 5.8mg/g; secondly, the decisive factor for polycarboxylicacid plasticizer to disperse α-calcium sulfate hemihydrate particles was the steric hindrance of polycarboxylicacid plasticizer, and the maximum ζ potential of α-calcium sulfate hemihydrate with polycarboxylicacid plasticizer was-9.360mv, much less than β-calcium sulfate hemihydrate under the same conditions; finally, the perfect mixing content of polycarboxylicacid plasticizer was 0.3%~0.6%; it increased fluidity by 66%, to the maximum 300mm.
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Feng, Yan, Rongxin Guo et Zhiwei Lin. « Effect of Aluminum Sulfate and Succinic Acid on the Growth Law of α-Calcium Sulfate Hemihydrate under Microwave Irradiation ». Advances in Materials Science and Engineering 2021 (12 avril 2021) : 1–13. http://dx.doi.org/10.1155/2021/6630638.

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The existing α-hemihydrate gypsum preparation process has low production efficiency and high energy consumption. In this paper, α-type hemihydrate gypsum was prepared by microwave irradiation using phosphogypsum as the raw material, calcium chloride solution as the reaction medium, and succinic acid and aluminum sulfate as crystal-transforming agents. Both aluminum sulfate and succinic acid were studied to determine the mechanism influencing the effect on the growth of α-type hemihydrate gypsum crystals. This study found that, without added succinic acid or aluminum ions, the crystal transformation rate of α-calcium sulfate hemihydrate reached 96% with the average length-diameter ratio reaching 21 after 1 h; when the dosage of succinic acid was 0.02%, the crystal transformation rate of α-calcium sulfate hemihydrate reached 96% with the average length-diameter ratio reaching 1.5 after 1.5 h; and when the aluminum ion dosage was 5 mM, the crystal transformation rate of α-calcium sulfate hemihydrate reached 97% with the average length-diameter ratio reaching 12.3 after 1 h. In addition, it was discovered that the reaction time was significantly shortened under microwave irradiation, and with an increase in succinic acid content, the regulation of the microscopic morphology of the calcium sulfate hemihydrate crystals was continuously enhanced and the aspect ratio of the crystals was continuously reduced. The EDS and Fourier transform infrared spectroscopy (FTIR) analysis showed that succinic acid did not adsorb onto the hemihydrate gypsum crystal during the reaction under microwave irradiation. The X-ray photoelectron spectroscopy (XPS) analysis revealed that aluminum ions affected crystal growth by incorporating into calcium sulfate hemihydrate crystals after reacting with sulfate radicals.
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MATSUI, Hiroshi, Genzo HASHIZUME, Gin-ya ADACHI et Jiro SHIOKAWA. « Formation of prismatic .ALPHA.-calcium sulfate hemihydrate during oxidation of calcium sulfite hemihydrate. » NIPPON KAGAKU KAISHI, no 6 (1988) : 892–98. http://dx.doi.org/10.1246/nikkashi.1988.892.

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Wang, Yu Bin, Le Yu, Hua Wang et Ting Shu He. « Effect of Sodium Citrate on the Hydration Capacity of Hemihydrate Calcium Sulfate Whiskers ». Applied Mechanics and Materials 584-586 (juillet 2014) : 1618–21. http://dx.doi.org/10.4028/www.scientific.net/amm.584-586.1618.

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The influence of sodium citrate on the hydration capacity of hemihydrate calcium sulfate whiskers was investigated. The products were characterized by FTIR, SEM and XRD.The results show that the absorption of the sodium citrate on the surface of the hemihydrate calcium sulfate whiskers is not uniform, and the adsorption state also changed with the amount of sodium citrate. Sodium citrate plays role on the hydration capacity of hemihydrate calcium sulfate whiskers.
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Liu, Xian Feng, Jia Hui Peng, Ming Zheng Chen, Leng Bai et Liu Liu. « Effect of Butane Diacid on Crystal Morphology and Reaction Process of α-Calcium Sulfate Hemihydrate in Preparation from Flue Gas Desulphurization Gypsum ». Advanced Materials Research 838-841 (novembre 2013) : 2681–84. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.2681.

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Modifying crystal morphology was the key technology of the preparation of α-calcium sulfate hemihydrate from flue gas desulphurization gypsum using the hydrothermal method under atmospheric pressure. For exploring the mechanism of butane diacid effect on crystal morphology of α-calcium sulfate hemihydrate in preparation from flue gas desulphurization gypsum, the crystal morphology, convert ratio, and reaction process of α-calcium sulfate hemihydrate were studied by scanning electron microscope observation, and crystal water testing. The results showed, firstly, crystal modifier made the growth rates of crystal in all directions equal and made the crystal into hexagonal short column, by selectivity adsorbing on (111) crystal plane of α-calcium sulfate hemihydrate to form buffer film layer which hindered combining and growing of crystallization unit on the crystal plane of c-axis direction. Secondly, butane diacid was a good crystal modifier. When adding butane diacid of optimal amount of 0.02%~0.05%, the crystal morphology of α-calcium sulfate hemihydrate was satisfactory, the crystal length-diameter ratio was 1:1, but the convert ratio was only 91%~93%.
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Zhu, Xin Feng, Yu Bin Wang, Xiao Wang et Liu Shuan Yang. « Integration of Preparation and Stabilization for Hemihydrate Calcium Sulfate Whiskers ». Advanced Materials Research 239-242 (mai 2011) : 3074–77. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.3074.

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The integration process of hemihydrate calcium sulfate whiskers with optimum additives was carried out, and the influence of reagents on the crystal shape and stability of hemihydrate calcium sulfate whiskers was investigated too. The products were characterized by FT-IR, SEM and XRD.The results show that the integration of preparation and stabilization of hemihydrate calcium sulfate whiskers can be achieved with addition of 0.025% sodium stearate and 0.15% sodium oleate by adding agents in different steps.
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Chen, Chang, Yu Bin Wang, Le Yu, Ying Jie Song, Shan Shan Zhang et Ai Zhang. « Hydration Ability of Hemihydrate Calcium Sulphate Whiskers with Different Content of Sodium Phosphate ». Applied Mechanics and Materials 638-640 (septembre 2014) : 1346–49. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.1346.

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Different content of sodium phosphate was added into the hemihydrates sulphate whiskers for 30 min to 2h of standing time. The treated products were researched by SEM, TG-DSC and XRD. The results indicate that when the dosage of sodium phosphate was more than 0.10%, the morphology of hemihydrate calcium sulphate whisker was fully maintained. However, the crystal structure of the products had changed and the half water calcium sulfate turned into of dihydrate calcium sulphate when 0.10 wt% sodium phosphate added. With the increase of standing time, half water calcium sulfate whisker converted into dihydrate calcium sulphate whisker. Sodium phosphate could reduce hydration ability of half water calcium sulfate whisker when the content of sodium phosphate was more than 0.10%.
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Wang, Xiao, Yu Bin Wang, Liu Shuan Yang, Xiao Fei Wang et Jia Kuan Yang. « Stabilization Effect of Sodium Phosphate on Hemihydrate Calcium Sulfate Whiskers ». Advanced Materials Research 287-290 (juillet 2011) : 535–38. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.535.

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Stabilization effect of sodium phosphate on crystalline phase and crystal shape of hemihydrate calcium sulfate whiskers was investigated. Morphology, thermal stability and phase composition of stabilized hemihydrate calcium sulfate whiskers were characterized by means of SEM, DSC-TG and XRD respectively. Results indicated that crystalline shape of hemihydrate calcium sulfate whiskers could be invariable in two hours at 100 °C with addition of 0.10 wt % sodium phosphate for 20 min. Meanwhile sodium phosphate had a good effect on whiskers morphology stabilization.
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Dai, Hao, Shu Peng Zhang, Cheng Lan Ju et Dong Xu Li. « Influence of Calcium Sulfate Varieties on Properties of Calcium Aluminate Cement-Based Self-Leveling Mortars ». Key Engineering Materials 680 (février 2016) : 455–61. http://dx.doi.org/10.4028/www.scientific.net/kem.680.455.

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The effect of calcium sulfates varieties on the properties of calcium aluminate cement-based self-leveling mortar have been investigated, and the hydration kinetics, hydrated products and microstructures are characterized by isothermal calorimeter, X-ray diffraction and mercury intrusion porosimetry, respectively. The results show that the technological properties of mortars are significantly affected by calcium sulfate varieties and content. The setting times are shortened drastically with the addition of calcium sulfates. Mortars with hemihydrate show higher early strength and less drying shrinkage. In contrast, using anhydrite in mortars cause lower strength and higher drying shrinkage at early age but larger growth of strength in the late. The increasing calcium sulfates content may result in the delay of main hydration peak in the heat evolution curve. For formulation with hemihydrate, the appearance of main hydration peaks are advanced compared with formulation without addition of calcium sulfates. Moreover, mortar microstructures are optimized by addition of β-hemihydrate, the proportion of large pores are lower than that of mortars with anhydrite.
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Thèses sur le sujet "Hemihydrate de sulfate de calcium"

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Chan, Kwok-chu Timmy. « Calcium sulphate hemihydrate effect of humidity in storage / ». Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21129526.

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Ling, Yuanbing 1970. « Direct preparation of alpha-calcium sulfate hemihydrate from sulfuric acid ». Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84283.

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In this work, the crystallization of alpha-calcium sulfate hemihydrate in sulfuric acid solution and the correlation between its properties and preparation conditions by reaction of sulfuric acid with lime (CaO) have been thoroughly investigated. The research involved the study of conversion-dissolution of calcium sulfate dihydrate in H2SO4 solution, the measurement of solubilities, thermo-dynamic calculations and the preparation of alpha-CaSO4 ·0.5 H2O via different methods of reactive mixing of H2SO4 and CaO. It was found that the calcium sulfate solids can saturate the sulfuric acid solutions in only 5 minutes. The solubility of calcium sulfate hemihydrate in 0--3.0M H 2SO4 solution at 100°C was experimentally determined and thermodynamic calculations with the aid of FactSage and OLI have led to establishment of the phase diagram for the CaSO4-H2SO 4-H2O system. An operating window has been determined in terms of H2SO4 concentration, temperature and time within which alpha-hemihydrate can be produced by reaction of lime with H 2SO4. This window is defined as 0.6--1.1M H2SO 4 (steady-state concentrations), 98--105°C and 1 hour retention time. Dihydrate was found to form as intermediate phase quickly converting to hemihydrate. The kinetics of conversion depends on the acidity level.
For the standard preparation procedure of adding lime into hot sulfuric acid, alpha-hemihydrate grows in the c-axis direction much more rapidly than in other directions ending in the form of fine needle crystals. Also, independent of the shape of the seed particles, the resultant crystals of hemihydrate are needle-shaped, which suggests a "dissolution-recrystallization" mechanism. Upon prolonged equilibration in their acid-preparation solution hemihydrate needle-shape crystals become fibrous and eventually convert to anhydrite. It is believed that uptake of SO42- instead of Ca2+ is the rate-determining step in the hemihydrate crystallization process. The hot SO42--rich environment rendered most of the additives (particularly organic) tried ineffective. Trivalent cations such as Fe3+ and Al3+, are the only ones found to modify the crystal morphology from needle-shape to small "grain" type morphology.
Slow addition of H2SO4 solution to slaked lime - reverse procedure was found to favor the production of alpha-hemihydrate with column-shaped as opposed to needle-shaped crystal morphology within otherwise the same operating window, 0.6--1.1M H2SO4. Preliminary assessment of the properties of the alpha-hemihydrate materials synthesized in this work showed them to compare satisfactorily with other materials produced by conversion of dihydrate to hemihydrate.
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Nilles, Vera [Verfasser]. « Insights into the Retarding Mechanism of Linear Sodium Polyphosphates on the Hydration of α-Calcium Sulfate Hemihydrate / Vera Nilles ». München : Verlag Dr. Hut, 2012. http://d-nb.info/1021072931/34.

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Alvarez-Dalama, Alina 1960. « CALCIUM-SULFITE HEMIHYDRATE CRYSTALLIZATION IN LIQUORS WITH HIGH TOTAL DISSOLVED SOLIDS (GROWTH, SIZE DISTRIBUTION, NUCLEATION, HABIT) ». Thesis, The University of Arizona, 1986. http://hdl.handle.net/10150/275528.

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Rong, Yi. « Formation du sulfate de calcium hémihydrate de type α à partir de gypse par un procédé de dissolution-cristallisation : étude cinétique expérimentale et modélisation ». Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEM070/document.

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De nombreuses transformations de solides en solution, polymorphiques ou non, en industrie minérale ou pharmaceutique, se déroulent par la dissolution d'un premier solide en vue de la cristallisation du second. Au lieu de la voie traditionnelle de séchage, la transformation du gypse (sulfate de calcium dihydrate) en alpha-bassanite (sulfate de calcium hémihydrate) peut s’effectuer en solution aqueuse : en augmentant suffisamment la température, le gypse devient plus soluble dans l'eau que l’hémihydrate, qui a alors la possibilité de cristalliser. Un appareillage et un mode opératoire originaux ont été conçus pour investiguer la sensibilité de la cinétique de la transformation et des caractéristiques des cristaux d’hémihydrate obtenus à ces conditions opératoires. En effet, cette voie de dissolution-recristallisation permet le contrôle du facteur d'aspect des cristaux d’hémihydrate, voire celui de leur taille moyenne et de leur dispersion de taille, par le choix de ses conditions physico-chimiques : température, pH, utilisation d’additifs, et ensemencement de la solution avec des particules d’hémihydrate appropriées. Les techniques d'analyse images sont développées afin d'identifier le rapport d'aspect des particules. Un modèle cinétique prenant en compte la dissolution du gypse, la nucléation et la croissance du sulfate de calcium hémihydrate, les équilibres en phase aqueuse et de solubilité, a été élaboré, et ses équations résolues avec le logiciel MATLAB. Couplée à une méthode numérique d'optimisation, cette résolution sous MATLAB permet d'examiner la validité des hypothèses sur les processus retenus et d'identifier leurs paramètres cinétiques
In mineral or pharmaceutical industry, many transformations of solids in solution (polymorphic or not), take place by the dissolution of the first solid and the crystallization of the second solid. Instead of the traditional drying process, the conversion of gypsum (calcium sulfate dihydrate) to alpha-bassanite (calcium sulphate hemihydrate) can be carried out in aqueous solution by increasing the temperature sufficiently. At this moment, the gypsum becomes more soluble in water than the hemihydrate, which then has the possibility to crystallize. An apparatus and an original procedure have been designed to investigate the sensitivity of the kinetics of transformation and the characteristics of the hemihydrate crystals obtained under its operating conditions. In fact, this dissolution-recrystallization route allows to control the aspect ratio of the hemihydrate crystals, and even their average size and size dispersion, by the choice of its physicochemical conditions such as temperature, pH, use of additives, and seeding the solution with the appropriate hemihydrate particles. Image analysis techniques are developed to identify the aspect ratio of the particles.A kinetic model taking into account the dissolution of gypsum, the nucleation and the growth of calcium sulphate hemihydrate and their equilibrium in aqueous phase and solubility had been developed and the equations of this model are solved with the help of MATLAB software. Coupled with a numerical optimization method, this resolution under MATLAB makes it possible to examine the validity of the assumptions on the selected processes and to identify their kinetic parameters
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SIDQUI, MUSTAPHA. « Etude du comportement des osteoblastes et des osteoclastes de rat en culture au contact de biomateriaux a usage odontologique ». Paris 7, 1998. http://www.theses.fr/1998PA07GA01.

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陳國柱 et Kwok-chu Timmy Chan. « Calcium sulphate hemihydrate : effect of humidity in storage ». Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B21129526.

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Girgin, Seref. « Crystallization of alpha-calcium sulphate hemihydrate by aqueous reaction of calcium chloride with sulphuric acid ». Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=102980.

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The crystallization of alpha-calcium sulphate hemihydrate with simultaneous regeneration of HCl by controlling the reaction of H 2SO4 (2.6M-8M) with concentrated CaCl2 (1-3.5M) solution at 80°C was investigated. The research included 3 studies: (a) study of the kinetics and mechanism of CaSO4 dehydrate (DH) conversion to hemihydrate (HH) and anhydrite (AH) in variable composition CaCl2 -HCl media; (b) reactive crystallization of alpha-hemihydrate in a semi-batch reactor configuration following the LaMer Diagram concept; and (c) the study of crystal growth and metal uptake by seeded crystallization with and without the presence of several metal chloride salts. According to the first study, AH is the only stable phase in the range of electrolyte concentration and temperature investigated with DH and HH being either metastable or unstable. In the absence of CaCl2 and at 3M HCl concentration or higher DH converts directly to AH. Maintenance of 0.3M or higher CaCl2 concentration was found to render hemihydrate metastable hence making its production feasible. Solubility estimation of three CaSO4 phases with the aid of OLI Stream Analyser software helped to explain the observed phase transition sequence. SEM characterization further revealed the transition from DH to HH to be governed by the topochemical mechanism.
In the reactive crystallization study H2SO4 was the limiting reactant added to the CaCl2 solution up to 0.8 SO 4/Ca molar ratio. The nucleation and growth stages were successfully separated via supersaturation control achieved by regulated addition of the limiting reactant in multiple steps. This separation permitted the growth of the homogeneously nucleated crystals within the metastable zone to needle-shaped hexagonal crystals (acicular habit). Upon recycling (seeding) of the product further growth was achieved, producing crystals with 80 mum - volume based mean crystal diameter- or 100-120 mum length and 10-15 mum diameter. Growth of the seed crystals appeared to follow an agglomeration mechanism. However, in the presence of foreign metal cations (in particular divalent, Mg 2+, Fe2+, Ni2+ and trivalent, Al 3+, Fe3+) crystal growth was severely retarded via their apparent adsorption. Some of the metal cations, namely Na+, Ni2+, Al3+ were found to incorporate into the hemihydrate crystal structure to a variable extent from 0.3g/t for Na to 7g/t for Ni and 11g/t for Al. The chloride uptake was less than 10 ppm.
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Pierre, Alexandre. « Rhéologie de suspensions concentrées de sulfate de calcium ». Phd thesis, INSA de Rennes, 2013. http://tel.archives-ouvertes.fr/tel-00910334.

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Ce travail de recherche s'inscrit dans une volonté de développer des suspensions concentrées à application Génie Civil (chapes anhydrites, bétons cirés). Dans ce contexte industriel, l'étude est focalisée sur l'effet de l'introduction d'adjuvants de type polycarboxylate (PCP) sur les propriétés d'écoulement de suspensions formulées avec une anhydrite fortement réactive. Les travaux expérimentaux sont initiés par le développement de protocoles de caractérisation rhéologique étalonné sur un fluide modèle à seuil. Ceci permet d'évaluer l'effet de la taille de l'entrefer, de la rugosité des plateaux, du précisaillement ainsi que du type et de la durée de sollicitation. Nous avons alors défini un protocole unique, exploitable pour identifier la courbe d'écoulement des suspensions concentrées étudiées.. Les propriétés viscoélastiques des suspensions, évaluées aux faibles déformations, sont également caractérisées sous sollicitations oscillantes. Afin d'affiner la connaissance des structures moléculaires des différents adjuvants sélectionnés pour cette étude, des caractérisations physico-chimiques sont réalisées. Elles permettent de distinguer plusieurs paramètres caractéristiques des adjuvants : masse molaire, indice de polymolécularité et sensibilité à la température en fonction d'un milieu alcalin ou neutre. Des mesures d'adsorptions ont également été réalisées sur deux adjuvants. Nous montrons ainsi que le phénomène d'adsorption semble conditionné par les propriétés du milieu, notamment par la présence de chaux. L'étude rhéologique paramétrique montre que des modifications sensibles de la réponse peuvent apparaître en fonction de l'adjuvant utilisé et de la concentration de la suspension. Les évolutions des indicateurs de consistance et de contrainte seuil de mise en écoulement en fonction de la fraction volumique solide et du dosage en adjuvant sont identifiées. Les résultats sont interprétés en ajustant un modèle de type Krieger-Dougherty. L'évolution du paramètre puissance de ce modèle peut être interprétée comme une modification de la forme et de la rugosité du grain couvert par des molécules de PCP adsorbées. Les paramètres moléculaires conditionnant le plus la rhéologie des suspensions concentrées étudiées sont la masse molaire et l'indice de polymolécularité. L'interprétation des résultats est moins tranchée vis-à-vis du seuil de mise en écoulement que vis-à-vis de la consistance. Dès lors, nous avons mis en évidence la relation seuil-consistance. Sur le plan pratique, se restreindre à l'estimation du seuil de mise en écoulement des suspensions devient pertinent. À cette fin, un modèle analytique permettant d'estimer la contrainte seuil de mise en écoulement à partir d'un test d'écoulement libre sur une surface plane est proposé. L'objectif est d'apporter une amélioration aux modèles existants lorsque l'écoulement est à la frontière entre régime d'affaissement et régime d'étalement. L'analyse, qui peut être généralisée à l'étude de tous types de fluides complexes à seuil, conduit à une meilleure évaluation de la contrainte seuil. En croisant l'information de tests d'étalement et de vidange au cône de Marsh, nous montrons ainsi qu'une rhéométrie rustique est tout à fait pertinente pour un usage industriel. La notion d'enrobage de grain est proposée pour modéliser, à l'échelle microscopique, le rôle de l'adjuvant sur l'interaction entre particules. L'ordre de grandeur de la distance interparticulaire estalors estimé entre 1 et 5 nm en exploitant des données de rhéométrie oscillante. Cette approche phénoménologique permet de mettre en évidence l'effet de la fraction volumique solide sur la distance interparticulaire. Finalement, l'étude de la rhéologie des suspensions concentrées est étendue à la transition liquide solide liée aux réactions d'hydratation. Le suivi de l'effort normal exercé sur une géométrie en contact avec la suspension peut s'interpréter comme un indicateur alternatif de prise.
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Kuthadi, Sandeep Kumar. « Laboratory Scale Study of Calcium Sulfate Hydration Forms ». TopSCHOLAR®, 2014. http://digitalcommons.wku.edu/theses/1467.

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This research is part of an ongoing project to create gypsum wallboards with enhanced fire resistance. The main goal of this research is to better understand the dehydration properties of calcium sulfate dihydrate, and the hydration of calcium sulfate hemihydrate as well as anhydrous calcium sulfate. The lab-scale kinetics of these processes were studied using thermogravimetric analysis and sorption analysis. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to characterize the products from different processes. In addition to the instrumental studies, small batches were handled in ovens and liquid slurries to better mimic the real world processing of these materials. The effects of temperature, time and humidity were investigated to determine their influence on the kinetics of dehydration/hydration of different hydration forms of calcium sulfate.
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Livres sur le sujet "Hemihydrate de sulfate de calcium"

1

Ragin, Margaret M. Recovery of sulfur from phosphogypsum : Conversion of calcium sulfate to calcium sulfide. Washington, D.C. (2401 E St., N.W., MS #9800, Washington 20241) : U.S. Dept. of the Interior, Bureau of Mines, 1990.

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Ragin, Margaret M. Recovery of sulfur from phosphogypsum : Conversion of calcium sulfate to calcium sulfide. Pgh. [i.e. Pittsburgh] PA : United States Dept. of the Interior, Bureau of Mines, 1990.

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Götz-Neunhoeffer, Friedlinde. Modelle zur Kinetik der Hydratation von Calciumaluminatzement mit Calciumsulfat aus kristallchemischer und mineralogischer sicht. Erlangen : Universitätsbund Erlangen-Nürnberg, 2006.

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Zhang, Zhongjie. Stability of calcium sulfate base course in a wet environment. Baton Rouge, LA : Louisiana Transportation Research Center, 2006.

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A, Rice David, dir. Recovery of sulfur from phosphogypsum : Conversion of calcium sulfide to sulfur. [Washington, D.C.] : Bureau of Mines, U.S. Dept. of the Interior, 1990.

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A, Tyburczy James, Ahrens T. J. 1936- et United States. National Aeronautics and Space Administration., dir. Shock-induced devolatization of calcium sulfate and implications for K-T extinctions. [Washington, DC : National Aeronautics and Space Administration, 1993.

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A, Tyburczy James, Ahrens T. J. 1936- et United States. National Aeronautics and Space Administration., dir. Shock-induced devolatization of calcium sulfate and implications for K-T extinctions. [Washington, DC : National Aeronautics and Space Administration, 1993.

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A, Tyburczy James, Ahrens T. J. 1936- et United States. National Aeronautics and Space Administration., dir. Shock-induced devolatization of calcium sulfate and implications for K-T extinctions. [Washington, DC : National Aeronautics and Space Administration, 1993.

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Hao, Yue-Li. Inhibition of acid production in coal refuse amended with calcium sulfate and calcium sulfite-containing flue gas desulfurization by-products. Columbus, OH : Graduate School, Ohio State University, 1998.

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Newton, Peter J. Sodium sulfate corrosion of silicon carbide fiber-reinforced calcium aluminosilicate glass-ceramic matrix composites. Monterey, Calif : Naval Postgraduate School, 1994.

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Chapitres de livres sur le sujet "Hemihydrate de sulfate de calcium"

1

Gooch, Jan W. « Calcium Sulfate Hemihydrate ». Dans Encyclopedic Dictionary of Polymers, 111. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_1844.

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Dong, Faqin, Hua He, Ping He, Wei Yang et Longhua Xu. « The Optimal Conditions of Preparation of Phosphogypsum-Based Calcium Sulfate Hemihydrate Whiskers by Hydrothermal Method Using Phosphogypsum ». Dans Springer Geochemistry/Mineralogy, 81–89. Cham : Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-13948-7_9.

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Bährle-Rapp, Marina. « Calcium Sulfate ». Dans Springer Lexikon Kosmetik und Körperpflege, 83. Berlin, Heidelberg : Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-71095-0_1519.

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Gooch, Jan W. « Calcium Sulfate ». Dans Encyclopedic Dictionary of Polymers, 111. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_1842.

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Gooch, Jan W. « Calcium Sulfate, Anhydrous ». Dans Encyclopedic Dictionary of Polymers, 111. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_1843.

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Gooch, Jan W. « Dead Burned Calcium Sulfate ». Dans Encyclopedic Dictionary of Polymers, 195. New York, NY : Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4419-6247-8_3309.

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Sumi, Lucy, Ann Corkery et J. L. Monkman. « Calcium Sulfate Content of Urban Air ». Dans Atmospheric Chemistry of Chlorine and Sulfur Compounds : Proceedings of a Symposium Held at the Robert A. Taft Sanitary Engineering Center, Cincinnati, Ohio, November 4-6, 1957, 69–80. Washington D. C. : American Geophysical Union, 2013. http://dx.doi.org/10.1029/gm003p0069.

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Witkamp, G. J., et G. M. Rosmalen. « Cadmium Incorporation in Calcium Sulfate Modifications ». Dans Environmental Technology, 148–50. Dordrecht : Springer Netherlands, 1987. http://dx.doi.org/10.1007/978-94-009-3663-8_18.

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Van Driessche, Alexander E. S., Tomasz M. Stawski, Liane G. Benning et Matthias Kellermeier. « Calcium Sulfate Precipitation Throughout Its Phase Diagram ». Dans New Perspectives on Mineral Nucleation and Growth, 227–56. Cham : Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-45669-0_12.

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Iwata, H., S. Nishio et M. Takeuchi. « The Inhibitory Effect of Urinary Heparan Sulfate and Chondroitin Sulfate on Calcium Oxalate Crystal Growth ». Dans Urolithiasis 2, 185–87. Boston, MA : Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-2556-1_60.

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Actes de conférences sur le sujet "Hemihydrate de sulfate de calcium"

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« Phosphated Superplasticizers as Effective Water Reducing Agent for α-Calcium Sulfate Hemihydrate Systems ». Dans SP-354 : Superplasticizers and Other Chemical Admixtures in Concrete - Conference Proceedings. American Concrete Institute, 2022. http://dx.doi.org/10.14359/51736070.

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Aufort, Julie, et Raffaella Demichelis. « Magnesium impurities decide the structure of calcium carbonate hemihydrate ». Dans Goldschmidt2021. France : European Association of Geochemistry, 2021. http://dx.doi.org/10.7185/gold2021.5573.

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Gibson, Gregory, Max Fazel et Stephen P. Chesters. « Cleaning Calcium Sulfate in Mine Water Membranes ». Dans The 5th World Congress on Mechanical, Chemical, and Material Engineering. Avestia Publishing, 2019. http://dx.doi.org/10.11159/mmme19.127.

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Rodríguez-Sendra, Josep, Noé Jiménez, Rubén Pico, Joan Faus et Francisco Camarena. « Calcium sulfate setting monitoring with ultrasonic backscattering analysis ». Dans 2019 International Congress on Ultrasonics. ASA, 2019. http://dx.doi.org/10.1121/2.0001093.

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Marchal, C., A. Noel, P. Bey, P. Aletti et M. Nadi. « Use of calcium sulfate for thermoluminescent thermal dosimetry ». Dans 1992 14th Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 1992. http://dx.doi.org/10.1109/iembs.1992.5760939.

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Marchal, Noel, Bey, Aletti et Nadi. « Use Of Calcium Sulfate For Thermoluminescent Thermal Dosimetry ». Dans Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE, 1992. http://dx.doi.org/10.1109/iembs.1992.589656.

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« Production of Sulfate-Resistant Concrete Containing High-Calcium Fly Ash and Sodium Sulfate Admixture ». Dans "SP-153 : Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete Proceedings Fifth International Conference Milwauk". American Concrete Institute, 1995. http://dx.doi.org/10.14359/1068.

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AlOtaibi, Fares, Mohammed Dahlan, Abdulaziz AlGhamdi, Almaz Sadykov et Karim Mechkak. « Mitigation of Calcium Sulfate Scale Deposition During Fracturing Treatments ». Dans SPE Kuwait Oil & Gas Show and Conference. Society of Petroleum Engineers, 2019. http://dx.doi.org/10.2118/198007-ms.

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Al-khaldi, Mohammed H., Ahmad AlJuhani, Saleh Haif Al-Mutairi et Mehmet Nihat Gurmen. « New Insights into the Removal of Calcium Sulfate Scale ». Dans SPE European Formation Damage Conference. Society of Petroleum Engineers, 2011. http://dx.doi.org/10.2118/144158-ms.

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Alissa, Faisal M., Norah W. Aljuryyed, Salem A. Balharth et Matteo Leoni. « Calcium Sulfate Scale Dissolution Efficiency by Various Chemicals Additives ». Dans SPE International Conference and Exhibition on Formation Damage Control. SPE, 2022. http://dx.doi.org/10.2118/208819-ms.

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Abstract Calcium sulfate scale is one of the challenges that face production stability in the oilfield industry as it is one of the most challenging scales to manage. Sulfate-scales are very hard to dissolve because of their low solubility-product. This work studies the dissolution capacity of different chemical additives and recipes on calcium sulfate scales. In this work, the maximum dissolution capacity (gram of scale/mole of chelating agent) of various chemical additives and recipes will be studied to evaluate the efficiency in the dissolution of Calcium Sulfate scales. Several experiments were conducted at multiple doses, pH, and in-presence of a catalyst. Potassium Carbonate was used as a catalyst in the dissolution of Calcium Sulfate scales. The performance of each additive was studied in a catalyzed and non-catalyzed pathway and with various. A Series of experiments conducted showed that parameters such as the additive-dose, pH, and a catalyst affect the dissolution efficiency. The dissolution performance efficiency of each additive (Lactic Acid, Citric Acid, N,N-Dicarboxymethyl Glutamic Acid (GLDA), and Gluconic Acid) was compared to the additive performance efficiency under a catalyzed pathway in a formulated recipe. The outcome of this work will contribute to the economic value added by finding the most efficient and cheap recipe to remove Calcium Sulfate scales from the wellbore.
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Rapports d'organisations sur le sujet "Hemihydrate de sulfate de calcium"

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Langton, C., et D. Stefanko. BLENDED CALCIUM ALUMINATE-CALCIUM SULFATE CEMENT-BASED GROUT FOR P-REACTOR VESSEL IN-SITU DECOMMISSIONING. Office of Scientific and Technical Information (OSTI), mars 2011. http://dx.doi.org/10.2172/1011327.

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Curcio, L. A., et E. F. Somerscales. Pool boiling of enhanced heat transfer surfaces in refrigerant-oil mixtures and aqueous calcium sulfate solutions. Office of Scientific and Technical Information (OSTI), août 1994. http://dx.doi.org/10.2172/10176548.

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Hao, Y. L., W. A. Dick, R. C. Stehouwer et J. M. Bigham. Production development and utilization of Zimmer Station wet FGD by-products. Final report. Volume 4, A laboratory study conducted in fulfillment of Phase 2, Objective 1 titled. Inhibition of acid production in coal refuse amended with calcium sulfite and calcium sulfate - containing FGD solids. Office of Scientific and Technical Information (OSTI), juin 1998. http://dx.doi.org/10.2172/1184771.

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Pines, Mark, Arieh Bar, David A. Carrino, Arnold I. Caplan et James A. Dennis. Extracellular Matrix Molecules of the Eggshell as Related to Eggshell Quality. United States Department of Agriculture, 1997. http://dx.doi.org/10.32747/1997.7575270.bard.

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The extracellular matrix of the mineralizing eggshell contains molecules hypothesized to be regulators biomineralization. To study eggshell matrix molecules, a bank of monoclonal antibodies was generated that bound demineralized eggshell matrix or localized to oviduct epithelium. Immunofluorescence staining revealed several staining patterns for antibodies that recognized secretory cells: staining for a majority of columnar lining cells, staining for a minor sub-set of columnar lining cells, intensified staining within epithelial crypts, and staining of the entire tubular gland. Western blotting with the antibody Epi2 on eggshell matrix showed binding to molecules with the apparent molecular weight of eggshell matrix dermatan sulfate proteoglycan (eggshell DSPG) (Carrino, et al., 1997). Immunoblots of cyanogen bromide-cleaved eggshell DSPG revealed broad band of reactivity that shifted to 25 kDa after chondroitinase digestion; indicating that the Epi2 binding site is located on a fragment which contains dermatan sulfate side chains. Immunogold labeling showed that Epi2 binds to secretory vesicles within the non-ciliated cells of the columnar epithelium, while the antibodies Tg1 and Tg2 bind to secretory vesicles of tubular gland cells. Immunogold labeling of demineralized shell matrix showed binding of Epi2, Tg1, and Tg2 to the matrix of the palisades layer, and showed little reactivity to other regions of the shell matrix. Quantification of the immunogold particles within the eggshell matrix revealed that antibodies Epi2 and Tg1 bind all calcified regions equally while antibody Tg2 has a greater affinity for the baseplate region of the calcium reserve assembly.
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Cram, Jana, Mary Levandowski, Kaci Fitzgibbon et Andrew Ray. Water resources summary for the Snake River and Jackson Lake Reservoir in Grand Teton National Park and John D. Rockefeller, Jr. Memorial Parkway : Preliminary analysis of 2016 data. National Park Service, juin 2021. http://dx.doi.org/10.36967/nrr-2285179.

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This report summarizes discharge and water quality monitoring data for the Snake River and Jackson Lake reservoir levels in Grand Teton National Park and John D. Rockefeller, Jr. Memorial Parkway for calendar year 2016. Annual and long-term discharge summaries and an evaluation of chemical conditions relative to state and federal water quality standards are presented. These results are considered provisional, and may be subject to change. River Discharge: Hydrographs for the Snake River at Flagg Ranch, WY, and Moose, WY, exhibit a general pattern of high early summer flows and lower baseflows occurring in late summer and fall. During much of 2016, flows at the Flagg Ranch monitoring location were similar to the 25th percentile of daily flows at that site. Peak flows at Flagg Ranch were similar to average peak flow from 1983 to 2015 but occurred eleven days earlier in the year compared to the long-term average. Peak flows and daily flows at the Moose monitoring station were below the long-term average. Peak flows occurred four days later than the long-term average. During summer months, the unnatural hydro-graph at the Moose monitoring location exhibited signs of flow regulation associated with the management of Jackson Lake. Water Quality Monitoring in the Snake River: Water quality in the Snake River exhibited seasonal variability over the sampling period. Specifically, total iron peaked during high flows. In contrast, chloride, sulfate, sodium, magnesium, and calcium levels were at their annual minimum during high flows. Jackson Lake Reservoir: Reservoir storage dynamics in Jackson Lake exhibit a pattern of spring filling associated with early snowmelt runoff reaching maximum storage in mid-summer (on or near July 1). During 2016, filling water levels and reservoir storage began to increase in Jackson Lake nearly two weeks earlier than the long-term average and coincident with increases in runoff-driven flows in the Snake River. Although peak storage in Jackson Lake was larger and occurred earlier than the long-term average, minimum storage levels were similar to the long-term average.
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Shenker, Moshe, Paul R. Bloom, Abraham Shaviv, Adina Paytan, Barbara J. Cade-Menun, Yona Chen et Jorge Tarchitzky. Fate of Phosphorus Originated from Treated Wastewater and Biosolids in Soils : Speciation, Transport, and Accumulation. United States Department of Agriculture, juin 2011. http://dx.doi.org/10.32747/2011.7697103.bard.

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Beneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levelsBeneficial use of reclaimed wastewater (RW) and biosolids (BS) in soils is accompanied by large input of sewage-originated P. Prolonged application may result in P accumulation up to levels that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction that impair plant nutrition, increase P loss, and promote eutrophication in downstream waters. This study aims to shed light on the RW- and BS-P forms in soils and to follow the processes that determine P reactivity, solubility, availability, and loss in RW and BS treated soils. The Technion group used sequential P extraction combined with measuring stable oxygen isotopic composition in phosphate (δ18OP) and with 31P-NMR studies to probe P speciation and transformations in soils irrigated with RW or fresh water (FW). The application of the δ18OP method to probe inorganic P (Pi) speciation and transformations in soils was developed through collaboration between the Technion and the UCSC groups. The method was used to trace Pi in water-, NaHCO3-, NaOH-, and HCl- P fractions in a calcareous clay soil (Acre, Israel) irrigated with RW or FW. The δ18OP signature changes during a month of incubation indicated biogeochemical processes. The water soluble Pi (WSPi) was affected by enzymatic activity yielding isotopic equilibrium with the water molecules in the soil solution. Further it interacted rapidly with the NaHCO3-Pi. The more stable Pi pools also exhibited isotopic alterations in the first two weeks after P application, likely related to microbial activity. Isotopic depletion which could result from organic P (PO) mineralization was followed by enrichment which may result from biologic discrimination in the uptake. Similar transformations were observed in both soils although transformations related to biological activity were more pronounced in the soil treated with RW. Specific P compounds were identified by the Technion group, using solution-state 31P-NMR in wastewater and in soil P extracts from Acre soils irrigated by RW and FW. Few identified PO compounds (e.g., D-glucose-6-phosphate) indicated coupled transformations of P and C in the wastewater. The RW soil retained higher P content, mainly in the labile fractions, but lower labile PO, than the FW soil; this and the fact that P species in the various soil extracts of the RW soil appear independent of P species in the RW are attributed to enhanced biological activity and P recycling in the RW soil. Consistent with that, both soils retained very similar P species in the soil pools. The HUJ group tested P stabilization to maximize the environmental safe application rates and the agronomic beneficial use of BS. Sequential P extraction indicated that the most reactive BS-P forms: WSP, membrane-P, and NaHCO3-P, were effectively stabilized by ferrous sulfate (FeSul), calcium oxide (CaO), or aluminum sulfate (alum). After applying the stabilized BS, or fresh BS (FBS), FBS compost (BSC), or P fertilizer (KH2PO4) to an alluvial soil, P availability was probed during 100 days of incubation. A plant-based bioassay indicated that P availability followed the order KH2PO4 >> alum-BS > BSC ≥ FBS > CaO-BS >> FeSul-BS. The WSPi concentration in soil increased following FBS or BSC application, and P mineralization further increased it during incubation. In contrast, the chemically stabilized BS reduced WSPi concentrations relative to the untreated soil. It was concluded that the chemically stabilized BS effectively controlled WSPi in the soil while still supplying P to support plant growth. Using the sequential extraction procedure the persistence of P availability in BS treated soils was shown to be of a long-term nature. 15 years after the last BS application to MN soils that were annually amended for 20 years by heavy rates of BS, about 25% of the added BS-P was found in the labile fractions. The UMN group further probed soil-P speciation in these soils by bulk and micro X-ray absorption near edge structure (XANES). This newly developed method was shown to be a powerful tool for P speciation in soils. In a control soil (no BS added), 54% of the total P was PO and it was mostly identified as phytic acid; 15% was identified as brushite and 26% as strengite. A corn crop BS amended soil included mostly P-Fe-peat complex, variscite and Al-P-peat complex but no Ca-P while in a BS-grass soil octacalcium phosphate was identified and o-phosphorylethanolamine or phytic acid was shown to dominate the PO fraction.
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