Journal articles on the topic 'Carbonate precipitation/dissolution'
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Patel, Ashim Kumar, Biswajit Mishra, Dewashish Upadhyay, and Kamal Lochan Pruseth. "Mineralogical and Geochemical Evidence of Dissolution-Reprecipitation Controlled Hydrothermal Rare Earth Element Mineralization in the Amba Dongar Carbonatite Complex, Gujarat, Western India." Economic Geology 117, no. 3 (May 1, 2022): 683–702. http://dx.doi.org/10.5382/econgeo.4890.
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Abstract The Amba Dongar carbonatite complex in western India comprises an inner ring of carbonatite breccia surrounded by a sövite ring dike. The various carbonatite units in the body include calcite carbonatite, alvikite, dolomite carbonatite, and ankerite carbonatite. The carbonate phases (calcite and ankerite) occur as phenocrysts, groundmass phases, fresh primary grains, and partially altered grains and/or pseudomorphs when hydrothermally overprinted. Rare earth element (REE) enrichment in the groundmass/altered calcite grains compared to the magmatic ones is ascribed to the presence of micron-sized REE phases. Fluorapatite and pyrochlore constitute important accessory phases that are altered to variable extents. Higher concentrations of Sr, Si, and REEs in fluorapatite are suggestive of a magmatic origin. Fresh pyrochlore preserves its magmatic composition, characterized by low A-site vacancy and high F in the Y-site, which on alteration becomes poorer in Na, Ca, and F and displays an increase in vacancy. The C-O isotope compositions of the carbonates also corroborate the extensive low-temperature hydrothermal alteration of the carbonatites. The REE mineralization is the result of interaction of the carbonatite with a sulfur-bearing, F-rich hydrothermal fluid that exsolved from late-stage carbonatitic magmas. The hydrothermal fluids caused dissolution of the primary carbonates and simultaneous precipitation of REEs and other high field strength element (HFSE)-bearing minerals. Complex spatial associations of the magmatic minerals with the REE fluorocarbonates, [synchysite-(Ce), parisite-(Ce), bastnäsite-(Ce)] and florencite-(Ce) point to the formation of these REE phases as a consequence of postmagmatic hydrothermal dissolution of the REEs from fluorapatite, pyrochlore, and carbonates. Ubiquitous association of fluorite and barite with REE minerals indicates transport of REEs as sulfate complexes in F-rich fluids. Precipitation of REE fluorocarbonates/florencite resulted from fluid-carbonate interaction, concomitant increase in pH, and decrease in temperature. Additionally, REE precipitation was aided and abetted by the removal of sulfur from the fluid by the precipitation of barite, which destabilized the REE sulfate complexes.
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He, Zhiliang, Qian Ding, Yujin Wo, Juntao Zhang, Ming Fan, and Xiaojuan Yue. "Experiment of Carbonate Dissolution: Implication for High Quality Carbonate Reservoir Formation in Deep and Ultradeep Basins." Geofluids 2017 (2017): 1–8. http://dx.doi.org/10.1155/2017/8439259.
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As the most frontiers in petroleum geology, the study of dissolution-based rock formation in deep carbonate reservoirs provides insight into pore development mechanism of petroleum reservoir space, while predicting reservoir distribution in deep-ultradeep layers. In this study, we conducted dissolution-precipitation experiments simulating surface to deep burial environments (open and semiopen systems). The effects of temperature, pressure, and dissolved ions on carbonate dissolution-precipitation were investigated under high temperature and pressure (~200°C; ~70 Mpa) with a series of petrographic and geochemical analytical methods. The results showed that the window-shape dissolution curve appeared in 75~150°C in the open system and 120~175°C in the semiopen system. Furthermore, the dissolution weight loss of carbonate rocks in the open system was higher than that of semiopen system, making it more favorable for gaining porosity. The type of fluid and rock largely determines the reservoir quality. In the open system, the dissolution weight loss of calcite was higher than that of dolomite with 0.3% CO2as the reaction fluid. In the semiopen system, the weight loss from dolomitic limestone prevailed with 0.3% CO2as the reaction fluid. Our study could provide theoretical basis for the prediction of high quality carbonate reservoirs in deep and ultradeep layers.
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Pan, Ling, Qiongfang Li, Yi Zhou, Na Song, Lujia Yu, Xuhui Wang, Ke Xiong, LikSen Yap, and Jianlin Huo. "Effects of different calcium sources on the mineralization and sand curing of CaCO3 by carbonic anhydrase-producing bacteria." RSC Advances 9, no. 70 (2019): 40827–34. http://dx.doi.org/10.1039/c9ra09025h.
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Di Lorenzo, Fulvio, Cristina Ruiz-Agudo, Aurelia Ibañez-Velasco, Rodrigo Gil-San Millán, Jorge Navarro, Encarnacion Ruiz-Agudo, and Carlos Rodriguez-Navarro. "The Carbonation of Wollastonite: A Model Reaction to Test Natural and Biomimetic Catalysts for Enhanced CO2 Sequestration." Minerals 8, no. 5 (May 11, 2018): 209. http://dx.doi.org/10.3390/min8050209.
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One of the most promising strategies for the safe and permanent disposal of anthropogenic CO2 is its conversion into carbonate minerals via the carbonation of calcium and magnesium silicates. However, the mechanism of such a reaction is not well constrained, and its slow kinetics is a handicap for the implementation of silicate mineral carbonation as an effective method for CO2 capture and storage (CCS). Here, we studied the different steps of wollastonite (CaSiO3) carbonation (silicate dissolution → carbonate precipitation) as a model CCS system for the screening of natural and biomimetic catalysts for this reaction. Tested catalysts included carbonic anhydrase (CA), a natural enzyme that catalyzes the reversible hydration of CO2(aq), and biomimetic metal-organic frameworks (MOFs). Our results show that dissolution is the rate-limiting step for wollastonite carbonation. The overall reaction progresses anisotropically along different [hkl] directions via a pseudomorphic interface-coupled dissolution–precipitation mechanism, leading to partial passivation via secondary surface precipitation of amorphous silica and calcite, which in both cases is anisotropic (i.e., (hkl)-specific). CA accelerates the final carbonate precipitation step but hinders the overall carbonation of wollastonite. Remarkably, one of the tested Zr-based MOFs accelerates the dissolution of the silicate. The use of MOFs for enhanced silicate dissolution alone or in combination with other natural or biomimetic catalysts for accelerated carbonation could represent a potentially effective strategy for enhanced mineral CCS.
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Haugen, Malin, Benyamine Benali, Tore Føyen, Wen Song, Martin A. Fernø, and Bergit Brattekås. "Calcite-functionalized micromodels for pore-scale investigations of CO2 storage security." E3S Web of Conferences 366 (2023): 01004. http://dx.doi.org/10.1051/e3sconf/202336601004.
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Carbon capture and subsequent storage (CCS) is identified as a necessity to achieve climate commitments. Permanent storage of carbon dioxide (CO2) in subsurface saline aquifers or depleted oil and gas reservoirs is feasible, but large-scale implementation of such storage has so far been slow. Although sandstone formations are currently most viable for CO2 sequestration, carbonates play an important role in widespread implementation of CCS; both due to the world-wide abundancy of saline aquifers in carbonate formations, and as candidates for CO2-EOR with combined storage. Acidification of formation brine during CO2 injection cause carbonate dissolution and development of reactive flow patterns. Using calcite-functionalization of micromodels we experimentally investigate fundamental pore-scale reactive transport dynamics relevant for carbonate CO2 storage security. Calcite-functionalized, two-dimensional and siliconbased, pore scale micromodels were used. Calcite precipitation was microbially induced from the bacteria Sporosarcina pasteurii and calcite grains were formed in-situ. This paper details an improved procedure for achieving controlled calcite precipitation in the pore space and characterizes the precipitation/mineralization process. The experimental setup featured a temperature-controlled micromodel holder attached to an automatic scanning stage. A high-resolution microscope enabled full-model (22x27 mm) image capture at resolution of 1.1 µm/pixel within 82 seconds. An in-house developed image-analysis python script was used to quantify porosity alterations due to calcite precipitation. The calcite-functionalized micromodels were found to replicate natural carbonate pore geometry and chemistry, and thus may be used to quantify calcite dissolution and reactive flow at the pore-scale.
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Darus, Fadilah, Mariatti Jaafar, and Nurazreena Ahmad. "Preparation of carbonate apatite scaffolds using different carbonate solution and soaking time." Processing and Application of Ceramics 13, no. 2 (2019): 139–48. http://dx.doi.org/10.2298/pac1902139d.
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The aim of this study is to fabricate CO3Ap scaffolds using a dissolution-precipitation reaction during hydrothermal treatment. Beta-tricalcium phosphate (?-TCP) was used as a precursor instead of the commonly used alpha-tricalcium phosphate (?-TCP). Here, the CO3Ap scaffold fabrication was accomplished in two steps: i) fabrication of ?-TCP scaffold using a combination of direct foaming and a sacrificial template and ii) hydrothermal conversion of the ?-TCP scaffold at 200?C in 2mol/l NaHCO3 and Na2CO3 aqueous solutions for 2-10 days. The effect of two different solutions was identified in the dissolution-precipitation reaction. CO3Ap scaffold with 8.95wt.% carbonate content was successfully fabricated using a NaHCO3 solution. The average pore size of the scaffold was approximately 180 ?m with 72% porosity. The average compressive strength of the CO3Ap scaffold was 0.7MPa. Based on the compressive strength and carbonate content results, NaHCO3 aqueous solutions were chosen as carbonate sources for phase transformation to fabricate a CO3Ap scaffold over 6 days.
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Offeddu, Francesco Giancarlo, Jordi Cama, Josep Maria Soler, and Christine V. Putnis. "Direct nanoscale observations of the coupled dissolution of calcite and dolomite and the precipitation of gypsum." Beilstein Journal of Nanotechnology 5 (August 11, 2014): 1245–53. http://dx.doi.org/10.3762/bjnano.5.138.
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In-situ atomic force microscopy (AFM) experiments were performed to study the overall process of dissolution of common carbonate minerals (calcite and dolomite) and precipitation of gypsum in Na2SO4 and CaSO4 solutions with pH values ranging from 2 to 6 at room temperature (23 ± 1 °C). The dissolution of the carbonate minerals took place at the (104) cleavage surfaces in sulfate-rich solutions undersaturated with respect to gypsum, by the formation of characteristic rhombohedral-shaped etch pits. Rounding of the etch pit corners was observed as solutions approached close-to-equilibrium conditions with respect to calcite. The calculated dissolution rates of calcite at pH 4.8 and 5.6 agreed with the values reported in the literature. When using solutions previously equilibrated with respect to gypsum, gypsum precipitation coupled with calcite dissolution showed short gypsum nucleation induction times. The gypsum precipitate quickly coated the calcite surface, forming arrow-like forms parallel to the crystallographic orientations of the calcite etch pits. Gypsum precipitation coupled with dolomite dissolution was slower than that of calcite, indicating the dissolution rate to be the rate-controlling step. The resulting gypsum coating partially covered the surface during the experimental duration of a few hours.
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Kunio, Ishikawa. "Carbonate Apatite Bone Replacement." Key Engineering Materials 587 (November 2013): 17–20. http://dx.doi.org/10.4028/www.scientific.net/kem.587.17.
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Inorganic component of bone is not hydroxyapatite but carbonate apatite. Although pure carbonate apatite (CO3Ap) has not been prepared due to the limited thermal stability of CO3Ap, dissolution - precipitation method using precursor block allows fabrication of pure CO3Ap. Fabrication of CO3Ap, cell response, tissue response and improvement of CO3Ap will be discussed.
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KLEIN, CARLA, and ANA MARIA PIMENTEL MIZUSAKI. "Cimentação Carbonática em Reservatórios Siliciclásticos - O Papel da Dolomita -." Pesquisas em Geociências 34, no. 1 (June 30, 2007): 91. http://dx.doi.org/10.22456/1807-9806.19465.
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Carbonates are important diagenetic cements in siliciclastic rocks thus important to determine these rocks as hydrocarbon reservoirs. The cement is the material had chemically precipitated partial or totally pore filling, affecting rock values of porosity and permeability. The acknowledgment of diagenetic patterns those are associated to the carbonatic cement precipitation and their impacts in the reservoirs quality can decrease the risks of exploration and exploitation of new reservoirs. Therefore is necessary the knowledge of origin and processes of carbonate cement’s precipitation. These cements have distribution patterns, mineralogy, textures and isotopic compositions which vary spatial and temporally, depending of perform conditions in each diagenetic environment. One of the most important diagenetic cement is dolomite and the dolomite’s group is compound by dolomite and ankerite. These minerals can be differentiated by analytical techniques such as optical petrography, staining techniques, cathodoluminescence, scanning electron microscopy and isotopes. Besides that, dolomite cement shape in a reservoir can display different forms: rhombs, poikilotopic and saddle in a variety of dimensions, pore filling, replacing detrital carbonate grains, concretions, nodules or stratified layers. Primaries calcite and aragonite replaced can promote precipitation of dolomite through increase of temperature and by presence of Mg-being fluids. The main entrance conditions to form dolomitic cement are: (i) alkaline solutions from pre-existence rocks weathering or evaporitc environments; (ii) marine waters; (iii) clay alteration; (iv) CaCO3 polymorphs dissolution; (v) dissolution of bioclasts. An interesting example of dolomitic cementation is the Carmópolis Member of the Muribeca Formation, hydrocarbon reservoir of the Camorim Field (Sergipe-Alagoas Basin, northeastern Brazil).
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Purgstaller, Bettina, Vasileios Mavromatis, Katja E. Goetschl, Florian R. Steindl, and Martin Dietzel. "Effect of temperature on the transformation of amorphous calcium magnesium carbonate with near-dolomite stoichiometry into high Mg-calcite." CrystEngComm 23, no. 9 (2021): 1969–81. http://dx.doi.org/10.1039/d0ce01679a.
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Kasioptas, A., C. Perdikouri, C. V. Putnis, and A. Putnis. "Pseudomorphic replacement of single calcium carbonate crystals by polycrystalline apatite." Mineralogical Magazine 72, no. 1 (February 2008): 77–80. http://dx.doi.org/10.1180/minmag.2008.072.1.77.
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AbstractDuring chemical weathering and natural hydrothermal reactions, apatite can form by replacing calcium carbonates. In hydrothermal experiments in which aragonite and calcite single crystals have been reacted with phosphate solutions, the carbonates are replaced by polycrystalline hydroxylapatite (HAP). In both cases the crystals have retained their overall morphology while their compositions have changed significantly. The HAP appears to have a crystallographic relationship to the parent carbonate crystals. The textural relationships are consistent with an interface-coupled dissolution-precipitation mechanism. Structural relationships and relative molar volumes and solubilities appear to be factors that greatly affect replacement reactions.
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Yutkin, M. P., C. J. Radke, and T. W. Patzek. "Chemical Compositions in Modified Salinity Waterflooding of Calcium Carbonate Reservoirs: Experiment." Transport in Porous Media 141, no. 2 (January 2022): 255–78. http://dx.doi.org/10.1007/s11242-021-01715-x.
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AbstractModified or low-salinity waterflooding of carbonate oil reservoirs is of considerable economic interest because of potentially inexpensive incremental oil production. The injected modified brine changes the surface chemistry of the carbonate rock and crude oil interfaces and detaches some of adhered crude oil. Composition design of brine modified to enhance oil recovery is determined by labor-intensive trial-and-error laboratory corefloods. Unfortunately, limestone, which predominantly consists of aqueous-reactive calcium carbonate, alters injected brine composition by mineral dissolution/precipitation. Accordingly, the rock reactivity hinders rational design of brines tailored to improve oil recovery. Previously, we presented a theoretical analysis of 1D, single-phase brine injection into calcium carbonate-rock that accounts for mineral dissolution, ion exchange, and dispersion (Yutkin et al. in SPE J 23(01):084–101, 2018. 10.2118/182829-PA). Here, we present the results of single-phase waterflood-brine experiments that verify the theoretical framework. We show that concentration histories eluted from Indiana limestone cores possess features characteristic of fast calcium carbonate dissolution, 2:1 ion exchange, and high dispersion. The injected brine reaches chemical equilibrium inside the porous rock even at injection rates higher than 3.5 $$\times$$ × 10$$^{-3}$$ - 3 m s$$^{-1}$$ - 1 (1000 ft/day). Ion exchange results in salinity waves observed experimentally, while high dispersion is responsible for long concentration history tails. Using the verified theoretical framework, we briefly explore how these processes modify aqueous-phase composition during the injection of designer brines into a calcium-carbonate reservoir. Because of high salinity of the initial and injected brines, ion exchange affects injected concentrations only in high surface area carbonates/limestones, such as chalks. Calcium-carbonate dissolution only affects aqueous solution pH. The rock surface composition is affected by all processes.
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Butts, Susan H. "Silicification." Paleontological Society Papers 20 (October 2014): 15–34. http://dx.doi.org/10.1017/s1089332600002783.
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Silicification is the replacement of original skeletal material accomplished through the concurrent dissolution of calcium carbonate and precipitation of silica. The processes is aided by the nucleation of silica to organic matter which surrounds the mineral crystallites within the shell. Factors that control silicification are those that influence the dissolution/precipitation process: shell mineralogy, shell ultrastructure (and, therefore, surface area), the amount and location of organic matter, and the character of the enclosing matrix. Silicification, like all types of fossilization, can produce taphonomic biases: it is far more common in Paleozoic than younger deposits, is more likely to occur in organisms with low-magnesium calcite shells, in carbonate sediments, and in environments with elevated dissolved silica.
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NG, Felix, and Bernard Hallet. "Patterning mechanisms in subglacial carbonate dissolution and deposition." Journal of Glaciology 48, no. 162 (2002): 386–400. http://dx.doi.org/10.3189/172756502781831214.
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AbstractDeglaciated bedrock surfaces in limestone areas often exhibit extensive patterning by solutional furrows and carbonate deposits that occur in close association with undulations in the bed topography. These features clearly result from subglacial dissolution and precipitation of calcite on the bed — induced, for instance, by melting and freezing in a regelation water film — but little is known about the observed morphology. In particular, it is intriguing that (i) the solutional furrows, whose formation requires explanation, are collectively organized into arcuate patterns, with characteristic spacing, and (ii) a fluted or “spiculed” surface texture is ubiquitous on the calcite deposits. Herein, we propose specific mechanisms for such patterning based on a theory where chemical processes in the water film are coupled to regelation physics. Solutional furrows reflect locally enhanced dissolution along stoss surfaces, where CO2-rich bubbles advected in the ice from up-glacier come into contact with the bed. The bubbles form as CO2 is exsolved from freezing film water at the lee of bed bumps. The flutings on the deposit are inherently the manifestation of a spatial instability at the interface where calcite precipitation occurs. Complex interactions underlie some of the striking glacier-bed features shaped by subglacial chemical processes.
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Meakin, Paul, and Bjørn Jamtveit. "Geological pattern formation by growth and dissolution in aqueous systems." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 466, no. 2115 (November 26, 2009): 659–94. http://dx.doi.org/10.1098/rspa.2009.0189.
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Progress towards the development of a better understanding of the formation of geological patterns in wet systems due to precipitation and dissolution is reviewed. Emphasis is placed on the formation of terraces, stalactites, stalagmites and other carbonate patterns due to precipitation from flowing supersaturated solutions and the formation of scallops by dissolution in undersaturated turbulent fluids. In addition, the formation of spherulites, dendrites and very large, essentially euhedral, crystals is discussed. In most cases, the formation of very similar patterns as a result of the freezing/melting of ice and the precipitation/dissolution of minerals strongly suggests that complexity associated with aqueous chemistry, interfacial chemistry and biological processes has only a secondary effect on these pattern formation processes.
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Jing, Xiuyan, Hongbin Yang, and Na Wang. "Study on the hydro-chemistry process after mixing between water and rocks." Water Quality Research Journal 54, no. 2 (September 25, 2018): 104–14. http://dx.doi.org/10.2166/wcc.2018.284.
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Abstract The chemical evolution of groundwater has received close attention from hydro-geologists. Northwest China largely consists of arid and semi-arid regions, where surface water and groundwater frequently exchange with each other, and where the mixing and water–rock interactions significantly affect the direction of water quality evolution. Based on experimental simulation, this paper investigates the interactions among the Yellow River water, groundwater and rocks in Yinchuan. The study found that when groundwater is mixed with the Yellow River water, the Yellow River water has a certain dilution effect on the hydro-chemical composition of groundwater; however, this effect is not simply diluted by proportion for no reaction between irons, but a portion of calcium, sulfur, and carbonate form precipitates. After mixing of the Yellow River water, groundwater and rocks, the pH increased, and the carbon dioxide system reached equilibrium again. In addition, CO32− was produced. While Na+ increase was mainly due to dissolution, SO42− decrease was because of precipitation. The precipitation or dissolution of Ca2+, Mg2+, and CO32− mainly depended on the mixing ratio between groundwater and river water, which suggested the reversible behavior of the dissolution-precipitation of carbonate minerals.
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Lopez-Aguayo, F., and J. M. Gonzalez Lopez. "Fibrous clays in the Almazan Basin (Iberian Range, Spain): genetic pattern in a calcareous lacustrine environment." Clay Minerals 30, no. 4 (December 1995): 395–406. http://dx.doi.org/10.1180/claymin.1995.030.4.11.
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AbstractThe Tertiary sediments of the southern part of Almazán basin (Province of Soria) exhibit two different facies with a sharp transition between them: (1) a coarse detrital facies; and (2) a lutite and carbonate facies. The vertical evolution of these facies in the different sections and boreholes is made up of several retrograde depositional sequences which evolve from proximal alluvial fans to carbonate lacustrine systems associated with the most distal fan sediments.The variation of the mineralogical association (carbonates, quartz, detrital clay minerals, palygorskite and, occasionally, sepiolite and smectites) allows four ‘mineralogical facies’ to be established. Each facies has a distinctive mineralogy related to the main genetic processes: (1) detrital facies; (2) transitional facies; (3) ‘chemical dolomite-palygorskite’ facies and (4) ‘chemical calcite’ facies. Although the carbonates (calcite and dolomite) are always the most abundant minerals, fibrous clay minerals are also important. The main mechanism of mineral authigenesis in this basin is chemical precipitation; the presence and distribution of carbonates and fibrous clay minerals is controlled by the relative concentrations of [Mg2+], [Ca2+], pCO2, pH and [SiO4H4]. Palygorskite occurrences, in these conditions, are related to dissolution-precipitation mechanisms of pre-existing detrital material.
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Enkhbayar, Urangoo, Uyen Erdenetsogt, Gungeregbat Narantsetseg, Lkhagvasuren Narangerel, Enkh-Oyun Tulgaa, Saruul Idesh, and Dolgorsuren Tsedenbal. "Optimum condition investigation on precipitating of calcium carbonate from natural limestone from Bayan soum." Mongolian Journal of Agricultural Sciences 31, no. 3 (February 15, 2021): 9–14. http://dx.doi.org/10.5564/mjas.v31i3.1525.
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Calcium carbonate (CaCO3) is the most widely used filler material in paper, paint, plastic, food, ceramic, cosmetic, medicine and other industries. In the present paper, precipitated calcium carbonate (PCC) has been produced from natural limestone powder (NLP) by the Calcination-Dissolution-Precipitation (CDP) method. Calcination, dissolution and precipitation experiments were carried out under various conditions including: calcination temperature (800, 850, 900, 950, 1000 and 1050 °C), dissolution time (5, 10, 15, 20 and 25 min) and precipitation time (10, 20, 30, 40, 50 and 60 sec). The analyses by XRF showed that the natural limestone contains 80.97% CaCO3 (47.39% CaO), produced PCC sample contains 94.47% CaCO3 (55.81% CaO). It can be seen that the produced PCC sample more purified than natural limestone.
Баянгийн ордны шохойн чулуунаас кальцийн карбонат тунадасжуулах тохиромжтой нөхцөлийн судалгаа
Кальцийн карбонатыг цаас, будаг, хуванцар, хүнс, керамик, косметик, эмийн болон бусад үйлдвэрлэлд маш өргөн ашигладаг. Бид энэхүү судалгаагаар байгалийн шохойн чулуунаас тунадасжуулсан кальцийн карбонатийг гарган авахдаа Calcination-Dissolution-Precipitation (CDP) буюу шатаан-уусгаж-тунадасжуулах аргыг ашигласан. Байгалийн шохойн чулууг шатаах туршилтыг 800, 850, 900, 950, 1000 болон 1050°C хэмд, уусгалтын хугацаа 5, 10, 15, 20 болон 25 минут, тунадасжуулах хугацааг 10, 20, 30, 40, 50 болон 60 секунд гэсэн хувилбаруудтай явуулсан. Рентген флюресценцийн шинжилгээгээр байгалийн шохойн чулууны дээжинд 80.97% CaCO3, тунадасжуулсан шохойн чулууны дээжинд 94.47% CaCO3 агуулагдаж байгаа нь тогтоогдсоноос үзвэл шатаан-уусгаж-тунадасжуулах аргаар илүү цэвэршилттэй кальцийн карбонат гарган авах боломжтойг харуулж байна.
Түлхүүр үг: Шатаах, уусгах, тунадасжуулах, CaCO3, Ca(OH)2
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Litvinova, Tatyana, and Ivan Oleynik. "Dissolution kinetics of rare earth metal phosphates in carbonate solutions of alkali metals." Записки Горного института 251 (October 29, 2021): 712–22. http://dx.doi.org/10.31897/pmi.2021.5.10.
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Treatment of apatite raw materials is associated with the formation of large-tonnage waste – phosphogypsum. The content of rare earth metals in such waste reaches 1 %, which makes it possible to consider it a technogenic source for obtaining rare earth metals and their compounds. Up to the present moment, there are neither processing plants, nor an efficient process flow to handle phosphogypsum dumps. It is rational to use a way that involves extraction of valuable components and overall reduction of phosphogypsum dumps. Such process flow is available with carbonate conversion of phosphogypsum to alkali metal or ammonium sulfate and calcium carbonate upon the condition of associated extraction of rare earth metal (REM) compounds. Associated extraction of REM compounds becomes possible since they form strong and stable complexes with hard bases according to Pearson, which among other things include carbonate, phosphate and sulfate anions. Formation of lanthanide complexes with inorganic oxygen-containing anions is facilitated by the formation of high-energy Ln-O bonds. The study focuses on the dissolution of lanthanide phosphates in carbonate media. It was established that formation of REM carbonate complexes from their phosphates is a spontaneous endothermic process and that formation of lanthanide carbonates and hydroxides serves as thermodynamic limitation of dissolution. A shift in equilibrium towards the formation of carbonate complexes is achieved by increasing the temperature to 90-100 °C and providing an excess of carbonate. The limiting stage of REM phosphate dissolution in carbonate media is external diffusion. This is indicated by increasing rate of the process with an intensification of stirring, first order of the reaction and the value of activation energy for phosphate dissolution from 27 to 60 kJ/mol. A combination of physical and chemical parameters of the process allowed to develop an engineering solution for associated REM extraction during carbonate conversion of phosphogypsum, which included a 4-5 h conversion of phosphogypsum at temperature of 90-110 °C by an alkali metal or ammonium carbonate solution with a concentration of 2-3 mol/l. As a result, a solution with alkali metal (ammonium) sulfate is obtained, which contains REMs in the form of carbonate complexes and calcium carbonate. The rate of REM extraction into the solution reaches no less than 93 %. Rare earth metals are separated from the mother liquor by precipitation or sorption on anion exchange resins, while the excess of alkali metal or ammonium carbonate is returned to the start of the process.
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McCutcheon, Jenine, Luke D. Nothdurft, Gregory E. Webb, David Paterson, and Gordon Southam. "Beachrock formation via microbial dissolution and re-precipitation of carbonate minerals." Marine Geology 382 (December 2016): 122–35. http://dx.doi.org/10.1016/j.margeo.2016.10.010.
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Sanders, Diethard, and Karl Krainer. "Taphonomy of Early Permian benthic assemblages (Carnic Alps, Austria): carbonate dissolution versus biogenic carbonate precipitation." Facies 51, no. 1-4 (June 7, 2005): 522–40. http://dx.doi.org/10.1007/s10347-005-0065-6.
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Sar, Suchandra, Caisa Samuelsson, Fredrik Engström, and Lena Sundqvist Ökvist. "Experimental Study on the Dissolution Behavior of Calcium Fluoride." Metals 10, no. 8 (July 22, 2020): 988. http://dx.doi.org/10.3390/met10080988.
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The presence of halogens has an adverse effect on the zinc extraction process through electrowinning, the last phase of the RLE (Roasting, Leaching and Electrowinning) zinc extraction route. Fluoride (F−) may be present as calcium fluoride (CaF2) and this is, for example, the case in double leached Waelz oxide (DLWO). Efficient removal of F− from primary and secondary raw materials for zinc extraction results in a simplified process and increases flexibility in the selection of raw materials. Understanding of the solubility behavior of pure CaF2 can give valuable information on treatment for maximized halogen removal. Dissolution of CaF2 was studied with the addition of sodium carbonate (Na2CO3) and sodium bicarbonate (NaHCO3). Dissolution studies were combined with thermodynamic calculations to understand the solubility behavior of CaF2 under different conditions. Results from the experiments and the thermodynamic calculations show that Na2CO3 and NaHCO3 have similar behavior if the pH is controlled at the same value. The available carbonate (CO32−) ion in the system limits the concentration of calcium (Ca2+) ion by precipitation of CaCO3, which enhances the dissolution of CaF2. At higher temperatures and pH, calcite, vaterite, and aragonite were formed and co-precipitation of CaF2 along with calcium carbonate (CaCO3) was observed. At lower temperatures and lower pH levels, only calcite and vaterite were formed and a coating by CaCO3 on CaF2 was found to hinder complete dissolution reaction. The results of this study indicate that the temperature along with the reagents used for the dissolution tests have a significant impact on the CaCO3 polymorph mixture (calcite, vaterite and aragonite) formation.
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Yang, Leilei, Linjiao Yu, Donghua Chen, Keyu Liu, Peng Yang, and Xinwei Li. "Effects of Dolomitization on Porosity during Various Sedimentation-Diagenesis Processes in Carbonate Reservoirs." Minerals 10, no. 6 (June 25, 2020): 574. http://dx.doi.org/10.3390/min10060574.
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Carbonate reservoirs, especially dolomite reservoirs, contain large reserves of oil and gas. The complex diagenesis is quite challenging to document the dolomite reservoirs formation and evolution mechanism. Porosity development and evolution in dolomite reservoirs primarily reflect the comprehensive effect of mineral dissolution/precipitation during dolomitization. In this study, multicomponent multiphase flow and solute transport simulation was employed to investigate dolomitization in the deep carbonate strata of the Tarim Basin, Northwest China, where active exploration is currently under way. One- and two-dimensional numerical models with various temperatures, fluid compositions and hydrodynamic characteristics were established to quantificationally study dolomitization and its effect on porosity. After determining the main control factors, detailed petrologic characteristics in the studied area were also analyzed to establish four corresponding diagenetic numerical models under different sedimentary environments. These models enabled a systematic analysis of mineral dissolution/precipitation and a quantitative recovery of porosity evolution during various sedimentation-diagenesis processes. The results allowed for a quantitative evaluation and prediction of reservoir porosity, which would provide a basis for further oil and gas exploration in deep carbonate reservoirs.
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Chen, F., C. S. S. McCool, D. W. W. Green, and G. P. P. Willhite. "Experimental and Modeling Study of the Transport of Chromium Acetate Solutions Through Carbonate Rocks." SPE Journal 15, no. 02 (March 4, 2010): 349–67. http://dx.doi.org/10.2118/100064-pa.
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Summary Gelled polymer systems are applied to oil reservoirs to reduce water production and to increase sweep efficiencies in recovery processes. A common system consists of hydrolyzed polyacrylamide with a chromium (III) crosslinker. Transport of these chemicals through the reservoir rock is essential for a successful treatment. In carbonate reservoirs, dissolution of the carbonate raises the pH of the gelant to levels where chromium precipitates, robbing the gelant of crosslinker. The transport of chromium acetate solutions through dolomite rock material was studied by injecting various solutions through short cores and measuring Cr, Mg, and Ca concentrations and pH in the effluent. Chromium retention in the cores caused by precipitation was a rate-controlled process. A mathematical model was developed that described convection, dispersion, kinetic reactions of carbonate dissolution and chromium precipitation, and chemical equilibrium for reactions between aqueous components. Experimental data from this work and taken from literature were simulated by the model. One rate equation with one set of parameters described the steady-state values of chromium concentration exiting the cores after the breakthrough of the injected solutions.
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Huang, Feifei, Lujie Gao, Yiping Zou, Guoqiang Ma, Junjie Zhang, Shiqing Xu, ZhuXin Li, and Xiao Liang. "Akin solid–solid biphasic conversion of a Li–S battery achieved by coordinated carbonate electrolytes." Journal of Materials Chemistry A 7, no. 20 (2019): 12498–506. http://dx.doi.org/10.1039/c9ta02877c.
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The sulfur chemistry is transited from the conventional dissolution–precipitation category to solid–solid biphasic conversion by tuning the coordinating structure of the carbonate based electrolyte, paving the way for achieving Li–S batteries with lower E/S ratios.
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Castro, Diana Maria Hernandez, Janeth Alina Vidal Vargas, Erika Tomie Koroishi, Luis Fernando Lamas de Oliveira, and Osvair Vidal Trevisan. "Porosity and Permeability Alteration of Carbonates by CO2-Enriched Brine Injection." Materials Science Forum 965 (July 2019): 107–15. http://dx.doi.org/10.4028/www.scientific.net/msf.965.107.
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Some carbonate reservoirs are known for their high CO2 content in oil. One possibility to handle this gas without environmental problems is to reinject it into the reservoir. Injection of carbonated water has been drawing attention because it is an advantageous technique when compared to gaseous CO2 injection, due to its improvement in mobility in the reservoir. The objective of this study is to evaluate the phenomenon of dissolution and precipitation during carbonated water injection in carbonate rocks. These effects are identified by analyzing the porosity variations through X-ray computer tomography images and permeability profile, determined indirectly by pressure transducers that measured the differential pressure by the fluid at the inlet and outlet of the core holders. The Coreflooding test were carried out with two core holders in series to represent a near region at the reservoir by the injection of brine saturated with 25% of CO2 in reservoir samples, composed of dolomite, calcite and clay. The test were performed using the following reservoir conditions of 8,500 psi at 70°C. Based on the experimental data provided by CT images, it can be seen that the core porosity increases or decrease during carbonated water injection due to coexistence of dissolution (increase of porosity) and precipitation (decrease of porosity) along the samples. These phenomena are observed in regions with high heterogeneity in porosity. In addition, the mineralogy of the cores is composed by three minerals, which influence in the capacity of reaction with carbonated water. For the experiment, the core placed in the core holder one presented a porosity increase and the second one decreased. On the other hand, the permeability showed a significant increase for both cores, it is believed that, the injection promoted a preferential way flow (wormhole) that affected considerably the permeability of the rock. The novelty of the investigation is that the experiments were carried out using Brazilian pre-salt carbonate reservoir rocks with mineralogy composed basically by dolomite, calcite and clay. Also, experimental work was performed at reservoir operational conditions.
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Boutsougame, Abdelaziz, Lahcen El Youssfi, Hlima Aassine, Soufiane Khuili, Sidi Imad Cherkaoui, Hassane Ouazzani, and Mustapha Alaoui. "Impact of geology and climate change on wetlands: Case of Lake Aguelmam Azegza (Middle Atlas, Morocco)." E3S Web of Conferences 337 (2022): 01007. http://dx.doi.org/10.1051/e3sconf/202233701007.
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The AguelmamAzegza lake is located in the Middle Atlas mountain range, this region consists of carbonate rocks of Lias. It is the best-watered and richest region in Morocco in terms of wetlands, especially natural lakes, rivers and fresh springs. The lake’s water supply is ensured by the inflows of water in the form of underwater sources fed by precipitation (rain and snow) following tectonics and the genesis of karstic formations by the dissolution of carbonate rocks. The declining trend in lake levels in recent years results from the decrease in precipitation which decreases during these years.
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Gagné-Turcotte, Roselyne, Nicolas Reynier, Dominic Larivière, Nail R. Zagrtdenov, Richard Goulet, and Philippa Huntsman. "Impact of Variability in Precipitation Patterns on the Geochemistry of Pyritic Uranium Tailings Rehabilitated with Saturated Cover Technology." Mining 2, no. 2 (June 4, 2022): 385–401. http://dx.doi.org/10.3390/mining2020020.
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Increasing variability in precipitation patterns is expected to result from climate change in Canada. This effect has the potential to affect the performances of saturated covers in inhibiting acid rock drainage (ARD) and metal leaching (ML) processes. Because ARD and ML may cause the release of deleterious chemical species into the environment, such climate-change-driven impact was investigated using trickle leach columns. The physical, chemical, and mineralogical characteristics of the tailings as well as chemical composition of the leachate were measured before and after the column study. Results from the experiment showed that higher variability in precipitation regimes could enhance leaching of uranium. Leaching ranged from 67.1 to 90.1% of the total amount of U, with greater values associated with higher variability in precipitation patterns. Lower water levels and prolonged drought periods led to higher oxygen fluxes to the U tailings and dissolution of carbonate-bearing minerals. The release of carbonates could have enhanced uranium leaching through the formation of stable uranium-carbonate complexes in solution. Overall, this study shows that water level variation caused by varying precipitation patterns can significantly affect the drainage chemistry of saturated cover systems for which the level fluctuates freely near the tailings–cover interface.
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Ma, Zhi Yuan, Hua Yan, Xin Zhou, and Chen Hou. "Impact of Carbonate Scaling on the Efficiency of Used Geothermal Water Reinjection from Low-Middle Temperature Geothermal Fluid in Xianyang Porous Geothermal Field, NW China." Advanced Materials Research 614-615 (December 2012): 307–10. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.307.
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In low-middle temperature porous geothermal field, precipitation of carbonate from solution to form carbonate scale is confirmed as the main obstacle to efficient reinjection from the used hot fluids in Xianyang city, NW China. The carbonate deposits cause operational problems and may even clog pipeline and reinjection drillholes. For this reason, it's important to understand how impact of carbonate precipitation on the second-hand geothermal water before reinjection has been operated, which concern sustainable utilization of the geothermal water in Xianyang, the famous porous geothermal field in China. In this paper, firstly, different possible minerals precipitation from used geothermal fluid were discussed, and carbonate scaling was regarded as mineral for chemical clog by using combined with lab and chemical simulation method. Secondly, the key impacts of carbonate scaling on clog in reinjection holes such as temperature, degassing, pH, mixing, mineralization were demonstrated based on coupled simulation both in lab experiment and theoretical method. Lastly, the distribution of carbonate scaling and its degree in study area were calculated. The results show that, as the main mineral for precipitation, carbonate exist in most thermal-water wells of study area with the minor or medium scaling, and the carbonate scaling vary increasingly from bottom to top in a single reinjection drillhole, north to south in the study area. According to mineral-dissolution-precipitation equilibrium calculation carbonate saturated tend growth with the temperature and pH increases in study area. The influence of mineralization on carbonate clog is different, common-ion effect in the south of study area is given priority, but in the north salt effect is showed main effect. The analysis for impacts on carbonate clog reflect that carbonate deposit effect are very complicated, which interact each other.
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Johnston, Vanessa, Andrea Martín-Pérez, Sara Skok, and Janez Mulec. "Microbially-mediated carbonate dissolution and precipitation; towards a protocol for ex-situ, cave-analogue cultivation experiments." International Journal of Speleology 50, no. 2 (April 2021): 137–55. http://dx.doi.org/10.5038/1827-806x.50.2.2372.
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Subterranean calcite dissolution and precipitation are often considered as strictly geochemical processes. The active involvement of microbes in these processes is commonly underestimated in the literature due to general oligotrophic conditions in caves, except in particular cave conditions, such as sulfidic caves and moonmilk deposits, where the presence of microbes likely plays a key role in mineral deposition. Here, we study the possible involvement of microbes from Postojna Cave, Slovenia, in carbonate dissolution (litholysis) and precipitation (lithogenesis). Microbes were sampled from small pools below hydrologically diverse drip sites and incubated on polished limestone tablets at 10 and 20°C for 2 and 14 weeks under cave-analogue conditions. The tablets were then observed under scanning electron microscope to investigate microbe–rock interactions. Our experiments showed the presence of various microbial morphotypes, often associated with extracellular polymeric substances, firmly attached on the surfaces. Unfortunately, our surface sterilization method using 96% and 70% ethanol could not establish the complete aseptic conditions in deep natural cracks in the experimental limestone tablets. Nonetheless, our results emulate the interaction of environmental microbes with limestone rock. Conspicuous calcite dissolution and precipitation were observed in association with these microbes. Furthermore, we show evidence of entombment of microbes in a Si-rich precipitate during nutrient-depleted growth conditions and we suggest that microbial involvement in silica mobilization under ambient conditions may be a widespread and often overlooked phenomenon. Our findings have important implications for microbial-mediation of cave carbonate dissolution and precipitation, including the preservation of past climate proxy signals in speleothems and prehistoric cave art. Improvements to the methodology and further work are suggested to enable more robust ex-situ cultivation experiments in the future, facilitating better and more detailed research into this topic.
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Choi, Hanna, Jaeyeon Kim, Byoung Ohan Shim, and Dong-hun Kim. "Characterization of Aquifer Hydrochemistry from the Operation of a Shallow Geothermal System." Water 12, no. 5 (May 13, 2020): 1377. http://dx.doi.org/10.3390/w12051377.
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The use of shallow geothermal energy systems utilizing groundwater temperature for the air-conditioning of buildings is increasing worldwide. The impact of these systems on groundwater quality has become crucial for environmental regulations and system design. For the long-term operation of geothermal systems, it is important to evaluate their influence on the geochemical properties of groundwater, including precipitation and dissolution of secondary minerals. This research was conducted in a real-scale geothermal system, consisting of a groundwater heat pump (GWHP). Hydrochemical data were obtained from samples collected from an aquifer before heating, during heating, and before cooling operations of the GWHP. The Langelier Saturation Index and Ryznar Stability Index were calculated, and the saturation index was simulated with the PHREEQC program. Evidence from water table variation, temperature change, and 87 Sr/ 86 Sr isotope distribution showed that groundwater flows from a well located on the northwest side of the geothermal well. The saturation index values showed that the pristine groundwater favors carbonate dissolution, however, manganese oxides are more sensitive to temperature than carbonate minerals. In addition, mineral precipitation and dissolution were found to vary with depth and temperature.
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Carter, B. R., J. R. Toggweiler, R. M. Key, and J. L. Sarmiento. "Processes determining the marine alkalinity and carbonate saturation distributions." Biogeosciences Discussions 11, no. 7 (July 21, 2014): 11139–78. http://dx.doi.org/10.5194/bgd-11-11139-2014.
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Abstract. We introduce a composite tracer, Alk*, that has a global distribution primarily determined by CaCO3 precipitation and dissolution. Alk* also highlights riverine alkalinity plumes that are due to dissolved calcium carbonate from land. We estimate the Arctic receives approximately twice the riverine alkalinity per unit area as the Atlantic, and 8 times that of the other oceans. Riverine inputs broadly elevate Alk* in the Arctic surface and particularly near river mouths. Strong net carbonate precipitation lowers basin mean Indian and Atlantic Alk*, while upwelling of dissolved CaCO3 rich deep waters elevates Northern Pacific and Southern Ocean Alk*. We use the Alk* distribution to estimate the carbonate saturation variability resulting from CaCO3 cycling and other processes. We show regional variations in surface carbonate saturation are due to temperature changes driving CO2 fluxes and, to a lesser extent, freshwater cycling. Calcium carbonate cycling plays a tertiary role. Monitoring the Alk* distribution would allow us to isolate the impact of acidification on biological calcification and remineralization.
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Bourillot, Raphaël, Emmanuelle Vennin, Christophe Dupraz, Aurélie Pace, Anneleen Foubert, Jean-Marie Rouchy, Patricia Patrier, et al. "The Record of Environmental and Microbial Signatures in Ancient Microbialites: The Terminal Carbonate Complex from the Neogene Basins of Southeastern Spain." Minerals 10, no. 3 (March 19, 2020): 276. http://dx.doi.org/10.3390/min10030276.
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The Messinian microbialites of the Terminal Carbonate Complex (TCC) from the Neogene basins of southeastern Spain show both diversified morphologies and an excellent preservation of primary microbial microstructures. Their stratigraphic architecture, fabric (micro-, meso-, and macro-fabric), and mineralogical composition were investigated in eight localities from three sedimentary basins of southeastern Spain: The Sorbas and Bajo Segura basins and the Agua Amarga depression. Two recurrent microbialite associations were distinguished. Laterally linked low relief stromatolites predominated in Microbialite Association 1 (MA1), which probably formed in low energy lagoons or lakes with fluctuating normal marine to hypersaline water. The microfabrics of MA1 reflected the predominance of microbially induced/influenced precipitation of carbonates and locally (Ca)-Mg-Al silicates. Microbialite Association 2 (MA2) developed in high energy wave and tidal influenced foreshore to shoreface, in normal marine to hypersaline water. High-relief buildups surrounded by mobile sediment (e.g., ooids or pellets) dominated in this environment. MA2 microbialites showed a significant proportion of thrombolitic mesofabric. Grain-rich microfabrics indicated that trapping and binding played a significant role in their accretion, together with microbially induced/influenced carbonate precipitation. The stratigraphic distribution of MA1 and MA2 was strongly influenced by water level changes, the morphology and nature of the substratum, and exposure to waves. MA1 favorably developed in protected areas during third to fourth order early transgression and regression phases. MA2 mostly formed during the late transgressions and early regressions in high energy coastal areas, often corresponding to fossil coral reefs. Platform scale syn-sedimentary gypsum deformation and dissolution enhanced microbial carbonate production, microbialites being thicker and more extended in zones of maximum deformation/dissolution. Microbial microstructures (e.g., microbial peloids) and microfossils were preserved in the microbialites. Dolomite microspheres and filaments showed many morphological similarities with some of the cyanobacteria observed in modern open marine and hypersaline microbialites. Dolomite potentially replaced a metastable carbonate phase during early diagenesis, possibly in close relationship with extracellular polymeric substances (EPS) degradation. Double-layered microspheres locally showed an inner coating made of (Ca)-Mg-Al silicates and carbonates. This mineral coating could have formed around coccoid cyanobacteria and indicated an elevated pH in the upper part of the microbial mats and a potential dissolution of diatoms as a source of silica. Massive primary dolomite production in TCC microbialites may have resulted from enhanced sulfate reduction possibly linked to the dissolving gypsum that would have provided large amounts of sulfate-rich brines to microbial mats. Our results open new perspectives for the interpretation of ancient microbialites associated with major evaporite deposits, from microbe to carbonate platform scales.
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Greenberg, Janet, and Mason Tomson. "Precipitation and dissolution kinetics and equilibria of aqueous ferrous carbonate vs temperature." Applied Geochemistry 7, no. 2 (March 1992): 185–90. http://dx.doi.org/10.1016/0883-2927(92)90036-3.
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Corbella, Merc�, Carlos Ayora, and Esteve Cardellach. "Hydrothermal mixing, carbonate dissolution and sulfide precipitation in Mississippi Valley-type deposits." Mineralium Deposita 39, no. 3 (May 1, 2004): 344–57. http://dx.doi.org/10.1007/s00126-004-0412-5.
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Wehrmann, L. M., N. J. Knab, H. Pirlet, V. Unnithan, C. Wild, and T. G. Ferdelman. "Carbon mineralization and carbonate preservation in modern cold-water coral reef sediments on the Norwegian shelf." Biogeosciences 6, no. 4 (April 27, 2009): 663–80. http://dx.doi.org/10.5194/bg-6-663-2009.
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Abstract. Cold-water coral ecosystems are considered hot-spots of biodiversity and biomass production and may be a regionally important contributor to carbonate production. The impact of these ecosystems on biogeochemical processes and carbonate preservation in associated sediments were studied at Røst Reef and Traenadjupet Reef, two modern (post-glacial) cold-water coral reefs on the Mid-Norwegian shelf. Sulfate and iron reduction as well as carbonate dissolution and precipitation were investigated by combining pore-water geochemical profiles, steady state modeling, as well as solid phase analyses and sulfate reduction rate measurements on gravity cores of up to 3.25 m length. Low extents of sulfate depletion and dissolved inorganic carbon (DIC) production, combined with sulfate reduction rates not exceeding 3 nmol S cm−3 d−1, suggested that overall anaerobic carbon mineralization in the sediments was low. These data showed that the coral fragment-bearing siliciclastic sediments were effectively decoupled from the productive pelagic ecosystem by the complex reef surface framework. Organic matter being mineralized by sulfate reduction was calculated to consist of 57% carbon bound in CH2O groups and 43% carbon in -CH2- groups. Methane concentrations were below 1 μM, and failed to support the hypothesis of a linkage between the distribution of cold-water coral reefs and the presence of hydrocarbon seepage. Reductive iron oxide dissolution linked to microbial sulfate reduction buffered the pore-water carbonate system and inhibited acid-driven coral skeleton dissolution. A large pool of reactive iron was available leading to the formation of iron sulfide minerals. Constant pore-water Ca2+, Mg2+ and Sr2+ concentrations in most cores and decreasing Ca2+ and Sr2+ concentrations with depth in core 23–18 GC indicated diagenetic carbonate precipitation. This was consistent with the excellent preservation of buried coral fragments.
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Yosi, Kusuma Eriwati, Arsista Dede, Triaminingsih Siti, and Sunarso. "Effect of CaSO4 Dissolution-Precipitation Time on Formation of Porous Carbonate Apatite as Bone Replacement Material." Journal of Biomimetics, Biomaterials and Biomedical Engineering 44 (February 2020): 83–90. http://dx.doi.org/10.4028/www.scientific.net/jbbbe.44.83.
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Introduction: Carbonate apatite type B (C-Ap) has been used as a bone replacement material because of its osteoconductive properties. Clinically, the pores formed in bone replacement material aid in cell mobility and nutrient supply, thereby increasing the bone regeneration ability. CO32- ions found in this material are useful for maintaining a stable physiological environment in the bone in order for it to be easily absorbed by osteoclasts. Porous C-Ap type B is formed using the dissolution–precipitation method by immersing porous anhydrous CaSO4 in a mixture of carbonate and phosphate solutions. Purpose: The present study aimed to evaluate the effect of immersion ofCaSO4using the dissolution–precipitation method on the formation of porous C-Ap type B with calcium sulfate precursor hemihydrate. Method: Porous C-Ap type B was produced usinga mixture of calcium sulfate hemihydrate precursors with 50 wt% polymethylmethacrylate (PMMA) porogen and distilled water. After hardening, the calcium sulfate dihydrate containing PMMA was burned in an oven at 700°C for 4 h to remove the PMMA. The specimen was immersed in a mixture of sodium phosphate (Na3PO4) and sodium carbonate (Na2CO3) for 6, 12, and 24 h. Phase testing through X-ray diffraction (XRD) using CuKα radiation at 40 kV and 40 mA was performed. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR, Thermo Fisher Scientific, Waltham, Massachusetts, USA) was used for detecting the functional groups of CO32- and PO42-. Results: XRD results showed the formation of C-Ap at 6 and 12 h, but the anhydrous CaSO4 phase remained; alternatively, this phase was absent after 24 h of immersion phase andFTIR showed the presence of the functional groups of CO32- compounds. Conclusion: Porous C-Ap type B can be formed from CaSO4 precursors after 24 h of immersion using the dissolution–precipitation method.
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Marwati, Siti, Regina Tutik Padmaningrum, and Sunarto Sunarto. "RECOVERY OF GOLD (Au) AND SILVER (Ag) METALS IN THE ELECTRONIC WASTE THROUGH MULTILEVEL PRECIPITATION PROCESS." Jurnal Sains Dasar 4, no. 2 (May 20, 2016): 190. http://dx.doi.org/10.21831/jsd.v4i2.9099.
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This research aims to determine the percent recovery of gold (Au) and silver (Ag) in the electronic waste such as CD-RW and determine the purity of gold and silver metals in the electronic waste such as CD-RW that through multilevel precipitation process. The first step was the optimization of the concentration of thiourea and time dissolution of gold and silver in the sample. The concentration of thiourea and the time dissolution optimum obtained from conentration of gold and silver maximum. By The percent recovery of gold and silver are determined by comparing the concentration of gold and silver between in the solution sample and in the sample without dissolution that be analyzed by XRF. The scond step was the multilevel precipitation process and calcination. Precipitation and calcination of the filtrat was dissolution results in the optimum condition. Reagent used was a solution of hydrochloric acid and potassium carbonate. The precipitation gold and silver produced from the precipitation of dissolution again and then be analyzed by atomic absorption spectrophotometry. The purity was determined by comparing the weight of gold and silver between in the precipitate and in the solution. The results of this research showed that the percent recovery of the silver in the CD-RW through the process dissolution with thiourea 10 g/L and 4 hours soaking time were 21.09 %. The purity silver preipitate were 0.15 %. The percent recovery and the purity of gold can not be determined because the gold contained in the sample were not detected or below the limit of detection equipment. Keywords: recovery, gold, silver, electronic waste
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Lee, Yeonkyeong, Hyemin Park, Jeonghwan Lee, and Wonmo Sung. "Enhanced oil recovery efficiency of low-salinity water flooding in oil reservoirs including Fe2+ ions." Energy Exploration & Exploitation 37, no. 1 (September 23, 2018): 355–74. http://dx.doi.org/10.1177/0144598718800727.
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The low-salinity waterflooding is an attractive eco-friendly producing method, recently, for carbonate reservoirs. When ferrous ion is present in the formation water, that is, acidic water, the injection of low-salinity water generally with neutral pH can yield precipitation or dissolution of Fe-minerals by pH mixing effect. FeSO4 and pyrite can be precipitated and re-dissolved, or vice versa, while siderite and Fe(OH)2 are insoluble which are precipitated, causing permeability reduction. Particularly, pyrite chemically reacts with low-salinity water and release sulfate ion, altering the wettability, favorably, to water-wet. In this aspect, we analyzed oil production focusing on dissolution of Fe-minerals and Fe-precipitation using a commercial compositional reservoir simulator. From the simulation results, the quantities of precipitation and dissolution were enormously large regardless of the type of Fe-minerals and there was almost no difference in terms of total volume in this system. However, among Fe-minerals, Fe(OH)2 precipitation and pyrite dissolution were noticeably large compared to troilite, FeSO4, and siderite. Therefore, it is essential to analyze precipitation or dissolution for each Fe-mineral, individually. Meanwhile, in dissolving process of pyrite, sulfate ions were released differently depending on the content of pyrite. Here, the magnitude of the generated sulfate ion was limited at certain level of pyrite content. Thus, it is necessary to pay attention for determining the concentration of sulfate ion in designing the composition of injection water. Ultimately, in the investigation of the efficiency of oil production, it was found that the oil production was enhanced due to an additional sulfate ion generated from FeS2 dissolution.
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Heydarizad, Mojtaba, Luis Gimeno, Somayeh Amiri, Masoud Minaei, and Hamid Ghalibaf Mohammadabadi. "A Comprehensive Overview of the Hydrochemical Characteristics of Precipitation across the Middle East." Water 14, no. 17 (August 28, 2022): 2657. http://dx.doi.org/10.3390/w14172657.
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The Middle East is located in a semiarid and arid region and is faced with an intense water shortage crisis. Therefore, studying the hydrochemical characteristics of precipitation as a main part of the water cycle has great importance in this region. The hydrochemical analyses showed that the quality of precipitation was mainly affected by dust particles originating from terrestrial environments, while marine and anthropogenic sources had a minor role. The statistical studies showed that the dissolution of evaporative and carbonate minerals mainly controlled the hydrochemistry of precipitation. Precipitation had an acidic nature in some stations and a nonacidic nature in others. Ca2+ was the major acid-neutralizing cation in the Middle East precipitation. Various machine learning methods were also used to simulate the TDS values in precipitation. The accuracy of the developed models was validated, showing that the model developed by the Gboost method was more accurate than those developed by other machine learning techniques due to its higher R2 values. To conclude, the hydrochemistry of precipitation showed significant variations across the Middle East. The dissolution of particles with terrestrial origins dominantly controlled the hydrochemistry of precipitation, while marine and anthropogenic sources had minor roles.
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Ma, Qingshan, Weiya Ge, and Fujin Tian. "Geochemical Characteristics and Controlling Factors of Chemical Composition of Groundwater in a Part of the Nanchang Section of Ganfu Plain." Sustainability 14, no. 13 (June 30, 2022): 7976. http://dx.doi.org/10.3390/su14137976.
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This work aims to investigate the hydrochemical characteristics and formation mechanisms of shallow groundwater in a part of the Nanchang section of Ganfu plain. The hydrochemical data from 90 groundwater samples were interpreted by the methods of mathematical statistics, Piper diagrams, Gibbs plots, ratio graphs of ions, and geochemical modeling. The results show that shallow groundwater is weakly acidic, the average concentration of cation in groundwater decrease in Ca2+ > Na+ > Mg2+ > K+, and the abundance is in the order HCO3− > NO3− > SO42− > Cl− for anions. The hydrochemical type of groundwater was dominated by HCO3-Na·Ca·Mg, HCO3·Cl-Na·Ca·Mg, and HCO3-Na·Ca. Moreover, the main controlling factor of groundwater hydrochemistry is water-rock interactions. Na+ and K+ mainly originate from the dissolution of halite. Ca2+ and Mg2+ are mainly controlled by carbonate dissolution, while the main anions come from the dissolution of evaporite and carbonate. The groundwater chemical evolution is affected by the dissolution and precipitation of the mineral phase and cation exchange.
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Cheng, Songlin. "Reaction-Path Formulation of a Simple Dissolution Model for Radiocarbon Dating Groundwater." Radiocarbon 34, no. 3 (1992): 646–53. http://dx.doi.org/10.1017/s0033822200063931.
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Since the pioneer publication of K. O. Münnich (1957), 14C systematics have been used in many hydrogeological studies. Because of the complexity of carbon geochemistry, numerous models have been proposed to correct the dilution effect of “dead” carbon in groundwater. All the 14C correction models for dating groundwater are based on either open- or closed-system conditions. I present here a simple model that accounts for the effects of both open- and closed-system dissolution of carbonate and aluminosilicate minerals. For systems involving precipitation of carbonate minerals and redox reactions of organic matter, reaction-path simulations are essential for reliable 14C dating of groundwater.
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Rassmann, Jens, Bruno Lansard, Lara Pozzato, and Christophe Rabouille. "Carbonate chemistry in sediment porewaters of the Rhône River delta driven by early diagenesis (northwestern Mediterranean)." Biogeosciences 13, no. 18 (September 27, 2016): 5379–94. http://dx.doi.org/10.5194/bg-13-5379-2016.
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Abstract. The Rhône River is the largest source of terrestrial organic and inorganic carbon for the Mediterranean Sea. A large fraction of this terrestrial carbon is either buried or mineralized in the sediments close to the river mouth. This mineralization follows aerobic and anaerobic pathways, with a range of impacts on calcium carbonate precipitation and dissolution in the sediment near the sediment–water interface. This study focuses on the production of dissolved inorganic carbon (DIC) and total alkalinity (TA) by early diagenesis, consequential pH variations and the effect on calcium carbonate precipitation or dissolution. The sediment porewater chemistry was investigated along a transect from the Rhône River outlet to the continental shelf. TA and concentrations of DIC, SO42− and Ca2+ were analyzed on bottom waters and extracted sediment porewaters, whereas pH and oxygen concentrations were measured in situ using microelectrodes. The average oxygen penetration depth into the sediment was 1.7 ± 0.4 mm close to the river mouth and 8.2 ± 2.6 mm in the continental shelf sediments, indicating intense respiration rates. Diffusive oxygen fluxes through the sediment–water interface ranged between 3 and 13 mmol O2 m−2 d−1. In the first 30 cm of the sediment, TA and DIC porewater concentrations increased with depth up to 48 mmol L−1 near the river outlet and up to 7 mmol L−1 on the shelf as a result of aerobic and anaerobic mineralization processes. Due to aerobic processes, at all stations pH decreased by 0.6 pH units in the oxic layer of the sediment accompanied by a decrease of the saturation state regarding calcium carbonate. In the anoxic layer of the sediments, sulfate reduction was the dominant mineralization process and was associated with an increase of porewater saturation state regarding calcium carbonate. Ultimately anoxic mineralization of organic matter caused calcium carbonate precipitation demonstrated by a large decrease in Ca2+ concentration with depth in the sediment. Carbonate precipitation decreased in the offshore direction, together with the carbon turnover and sulfate consumption in the sediments. The large production of porewater alkalinity characterizes these sediments as an alkalinity source to the water column, which may increase the CO2 buffering capacity of these coastal waters. Estuarine sediments should therefore receive more attention in future estimations of global carbon fluxes.
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DAITOU, Fumikazu, Michito MARUTA, Giichiro KAWACHI, Kanji TSURU, Shigeki MATSUYA, Yoshihiro TERADA, and Kunio ISHIKAWA. "Fabrication of carbonate apatite block based on internal dissolution-precipitation reaction of dicalcium phosphate and calcium carbonate." Dental Materials Journal 29, no. 3 (2010): 303–8. http://dx.doi.org/10.4012/dmj.2009-095.
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Alsaiari, H. A. A., A. Kan, and M. B. B. Tomson. "Effect of Calcium and Iron (II) Ions on the Precipitation of Calcium Carbonate and Ferrous Carbonate." SPE Journal 15, no. 02 (March 11, 2010): 294–300. http://dx.doi.org/10.2118/121553-pa.
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Summary This work was intended to study the interaction between ferrous-iron and calcium ions simultaneously toward carbonate ions in supersaturated solution in a continuous stirred tank reactor (CSTR) and to establish an acceptable experimental design as a preparation step to study the kinetics of other types of ferrous iron salts. The experiments were conducted in 0.5 M NaCl solution at 55°C. The pH values were between 6.2 and 7.8. It was found that calcium ions have a strong influence in increasing the solubility of iron carbonate. On the other hand, ferrous iron did not affect the solubility of calcium carbonate significantly. This might be caused by increasing the stability of ferrous iron carbonate complexes in the presence of calcium. Also, the molar ratios of calcium to iron in the solution were compared with their molar ratios in the precipitated salts. It was found that the relation was greater than unity; Rsolid/Rsolution = 2.39. Thus, calcium carbonate has a preference to precipitate. This result seems to be in agreement with water dissolution rates of divalent ions and also with reaction-rate constants of iron carbonate and calcium carbonate reported in the literature.
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Zou, B., C. S. McCool, D. W. Green, and G. P. Willhite. "A Study of the Chemical Interactions Between Brine Solutions and Dolomite." SPE Reservoir Evaluation & Engineering 3, no. 03 (June 1, 2000): 209–15. http://dx.doi.org/10.2118/64536-pa.
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Summary Application of gelled polymer treatments to change the flow characteristics of a reservoir is a viable improved oil recovery technique. Many gel systems are affected by the solution pH in that gel time is pH dependent. The treatment of carbonate reservoir rock is of particular concern because (1) fluid-rock interaction can alter the pH of the injected solution from the design value and (2) dissolution of carbonate can increase the divalent ion concentration, which can also affect gelation behavior. In this study, the interaction between injected potassium chloride brine and dolomite was investigated through displacement experiments in dolomite cores and mathematical modeling based on equilibrium thermodynamics. Parameters varied were pH of the injected solution, flow rate, and the common ion effect through variation of the calcium and magnesium ion concentrations in the injected solution. Core effluent values of pH and concentrations were measured. Experiments at different flow rates established conditions in which equilibrium was achieved in the core. Equilibrium values of pH were almost constant at a value of 10 when the injected pH was varied between 4 and 10. Results indicate that equilibrium conditions exist for most field conditions. A geochemical model was used to predict equilibrium pH and concentrations, as well as the amount of dolomite dissolved. The model accurately predicted effluent pH of experimental displacement data for the conditions wherein equilibrium was achieved. All model parameters were obtained from literature equilibrium data and were not dependent on curve fitting of the experimental data. Introduction Systems utilizing Cr(III) as the polymer crosslinker are probably the most frequently studied and used gelled polymer systems for water conformance treatments. Both xanthan and partially hydrolyzed polyacylamide form gels with Cr(III). Both of these gel systems are affected by the pH of the solution in at least two ways. One is that the gelation time decreases significantly with increasing pH.1 The other is that Cr(III) is subject to precipitation in solutions with pH over 5.5, and the precipitation is aggravated with increasing pH.2 The treatment of carbonate reservoir rock is of particular concern because of the fluid-rock interaction, which can alter the pH of the injected solution. Previous studies3–5 show that change of pH of the injected solution inhibits the propagation of Cr(III) in carbonate cores or sandstone cores containing carbonate as the solution flows through porous rock. Seright3 studied the propagation of chromium acetate or chromium chloride through Indiana limestone cores. Cr(III) concentration in the effluent never reached the injected concentration after injecting about 10 pore volumes of chromium solution for any case studied. Chromium propagated more rapidly when the counterion was acetate as opposed to chloride. No chromium was detected in the effluent after injecting 10 pore volumes of chromium chloride solution through a limestone core. Stavland et al.4 studied the retention of chromium(III) in Brent and Berea sandstone cores (with about 2% carbonate content). The authors found precipitation was the most important reason for chromium retention in cores. Precipitation was caused by the dissolution of carbonate minerals that increased the pH of the injected solution. Their experiments also revealed that the retention rate of Cr(III) was lower with less carbonate present in the cores. McCool et al.5 studied the interaction between a dolomite core and a xanthan-Cr(III) gel system. Significant amounts of Cr(III) precipitated because the pH in the injected solution increased due to the dissolution of dolomite. Equilibrium relations and the dissolution kinetics in dolomite-carbonic acid-water systems have been studied for such purposes as soil science, the study of secondary changes in sedimentary deposits, the neutralization of acid mine drainage, and the acidizing of petroleum wells. 6 Most previous studies were conducted in agitated batch reactors, rotating disk, or fluidized bed reactor systems in the laboratory by using relatively pure dolomitic rock or synthetic dolomite. A few investigators have studied the dissolution reaction using flow through packed-bed reactors or consolidated rock cores.7,8 Many investigators recognize the complexity of the dissolution of dolomite. Most have attempted to simplify the modeling by delineating the rate-limiting steps. It is apparent that in making assumptions and interpretations of data most investigators have often been limited by the type of apparatus, the size and origin of dolomite used, and the experimental conditions. Consequently, the kinetic equations and mechanisms proposed by different investigators explain their experimental data, but they are not easily generalized. The rate equations derived by Plummer and Busenberg9 and those from Chou et al.10 are often used to predict the dolomite dissolution rates within a 2- to 100-fold difference, depending on the reaction conditions. It is believed that the dissolution rate is controlled by surface reaction, reactant or product diffusion, or a combination depending on reaction conditions. Also, the dissolution of dolomite reaches equilibrium much faster in a closed-to-atmosphere system than in an open system in which the transport of carbon dioxide from the atmosphere is involved in the reactions. The dissolution rate is affected by the rock lithology such as impurity content, crystal size, rock texture, and Ca/Mg ratio in the rock and the injected solution chemistry such as the pH and composition. The effect of the rock formation on dolomite dissolution was the dominant interest in many previous investigations. Rauch and White7 investigated the effect of lithology on carbonate dissolution rate. The authors found that the dissolution rate decreased as the percentage of dolomite and disseminated insolubles increased. The general chemistry of dolomite dissolution has been studied extensively, though some dissolution mechanisms are still under debate. As a salt of a weak acid, dolomite dissolves in strong acid, carbonated water, and water by different mechanisms. In water, the general chemistry is C a M g ( C O 3 ) 2 = C a 2 + + M g 2 + + 2 C O 3 2 − . ( 1 ) When carbon dioxide is present, the dissolution has the reaction C a M g ( C O 3 ) 2 + 2 H 2 C O 3 = C a 2 + + M g 2 + + 4 H C O 3 − . ( 2 ) When in strong acidic solution, the following reaction occurs:6 C a M g ( C O 3 ) 2 + 4 H + = C a 2 + + M g 2 + + 2 C O 2 ( a q ) + 2 H 2 O . ( 3 )
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Mohd Sabri, Siti Noorzidah, Syazana Abu Bakar, Abdul Yazid Abdul Manaf, Siti Farhana Hisham, Mohamad Azmirruddin Ahmad, K. Jamuna Thevi, Kartini Noorsal, Khairul Anuar Shariff, and Kunio Ishikawa. "Phase Transformation of Biphasic Granules of Gypsum and Carbonated Apatite at Low Temperatures." Advanced Materials Research 1133 (January 2016): 50–54. http://dx.doi.org/10.4028/www.scientific.net/amr.1133.50.
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The purpose of this study was to prepare biphasic granules containing gypsum and carbonated apatite at low temperatures. The biphasic granules were prepared using dissolution-precipitation technique at three different temperatures 30°C, 40°C and 50°C. Characterization of the biphasic granules was determined by multiple analytical methods such as X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR), and CHN Analysis. The obtained granules were determined by XRD as biphasic granules containing bone apatite and gypsum. The cross-section of biphasic granules was observed by SEM. The formed bone apatite was identified as B-Type carbonated apatite using FTIR The carbonate content in biphasic granules fabricated at 30°C, 40°C and 50°C were recorded by CHN analysis as 5.0 wt%, 6.1 wt% and 6.25 wt%, respectively.
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Zhang, Shuo. "The relationship between organoclastic sulfate reduction and carbonate precipitation/dissolution in marine sediments." Marine Geology 428 (October 2020): 106284. http://dx.doi.org/10.1016/j.margeo.2020.106284.
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Singurindy, Olga, and Brian Berkowitz. "The role of fractures on coupled dissolution and precipitation patterns in carbonate rocks." Advances in Water Resources 28, no. 5 (May 2005): 507–21. http://dx.doi.org/10.1016/j.advwatres.2005.01.002.
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Stoltenberg, Laura, Kai G. Schulz, Tyler Cyronak, and Bradley D. Eyre. "Seasonal variability of calcium carbonate precipitation and dissolution in shallow coral reef sediments." Limnology and Oceanography 65, no. 4 (November 20, 2019): 876–91. http://dx.doi.org/10.1002/lno.11357.
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