The Experts below are selected from a list of 144 Experts worldwide ranked by ideXlab platform
Hasan Böke - One of the best experts on this subject based on the ideXlab platform.
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Quantification of CaCO3–CaSO3·0.5H2O–CaSO4·2H2O mixtures by FTIR analysis and its ANN model
Materials Letters, 2004Co-Authors: Hasan Böke, Serhan Ozdemir, Sedat Akkurt, E.hale Göktürk, Emine N. Caner SaltikAbstract:Abstract A new quantitative analysis method for mixtures of Calcium carbonate (CaCO 3 ), Calcium Sulphite hemihydrate (CaSO 3 ·1/2H 2 O) and gypsum (CaSO 4 ·2H 2 O) by FTIR spectroscopy is developed. The method involves the FTIR analysis of powder mixtures of several compositions on KBr disc specimens. Intensities of the resulting absorbance peaks for CaCO 3 , CaSO 3 ·1/2H 2 O and CaSO 4 ·2H 2 O at 1453, 980, 1146 cm −1 were used as input data for an artificial neural network (ANN) model, the output being the weight percent compositions of the mixtures. The training and testing data were randomly separated from the complete original data set. Testing of the model was done with successfully low-average error levels. The utility of the model is in the potential ability to use FTIR spectrum to predict the proportions of the three substances in unknown mixtures.
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Effect of some surfactants on SO2-marble reaction
Materials Letters, 2002Co-Authors: Hasan Böke, E.hale Göktürk, Emine N. Caner SaltikAbstract:In the polluted atmosphere, sulphur dioxide (SO2) reacts with calcite (CaCO3) in marble producing Calcium Sulphite hemihydrate (CaSO3·0.5 H2O) and gypsum (CaSO4·2H2O). Gypsum develops crust at rain-sheltered surfaces and then, being more soluble, accelerates erosion at areas exposed to rain. Eventually, all these lead to significant deformations in the appearance and structure of marble surfaces. Clearly, some precautions must be taken to stop or at least to slow down this deterioration process which destroys our cultural heritage. In this study, we have investigated the possibilities of preventing the SO2–marble reaction by using water-soluble surfactants: Abil Quat 3270 and Tween 20. Experiments for measuring their effects have been carried out at conditions simulating the dry deposition of SO2. Infrared spectrometry and scanning electron microscopy were used to analyze the mineralogical composition and morphology of the reaction products. The extent of sulphation reaction was calculated by determining Calcium Sulphite hemihydrate and gypsum quantitatively by an IR approach and also by weight increases observed during the progress of SO2–marble reaction. A 10% decrease is observed in the total sulphation with both surfactant applications. The results have been discussed in relation to the possible stages of sulphation reaction and surface reactions of calcite.
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Effect of airborne particle on SO2–calcite reaction
Applied Surface Science, 1999Co-Authors: Hasan Böke, Emine N. Caner-saltik, E.hale Göktürk, Şahinde DemirciAbstract:Abstract In modern urban atmosphere, sulphur dioxide (SO2) attacks calcite (CaCO3) in calcareous stone-producing gypsum (CaSO4·2H2O) which forms crust at rain sheltered surfaces and accelerates erosion at areas exposed to rain. The airborne particles collected on stone surfaces have always been considered to enhance the gypsum crust formation and thus it is believed that they should be removed from the surface to decrease the effects of SO2. In this study, our aim was to investigate this event by carrying out a series of experiments in laboratory using pure Calcium carbonate powder to represent calcareous stone. Sodium montmorillonite, activated carbon, ferric oxide, vanadium pentoxide and cupric chloride were mixed in the pure Calcium carbonate powder as substitutes of the airborne particles in the polluted atmosphere. The samples have been exposed at nearly 10 ppmv SO2 concentrations at 90% relative humidity conditions in a reaction chamber for several days. The mineralogical composition of the exposed samples were determined by X-ray diffraction (XRD) analysis and infrared spectrometer (IR). Sulphation reaction products, Calcium Sulphite hemihydrate, gypsum and unreacted calcite, were determined quantitatively using IR. Exposed samples have also been investigated morphologically using a scanning electron microscope (SEM). Experimental results reveal that Calcium Sulphite hemihydrate is the main reaction product of the SO2–calcite reaction. It turns out that airborne particles play an important catalytic role in the oxidation of Calcium Sulphite hemihydrate into gypsum, although their presence does not very significantly affect the extent of sulphation reaction. This behaviour of airborne particles is explained by the presence of liquid film on the Calcium carbonate surface where a series of reactions in the gas–liquid–solid interfaces takes place.
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Effect of airborne particle on SO2-calcite reaction
Applied Surface Science, 1999Co-Authors: Hasan Böke, Emine N. Caner-saltik, E.hale Göktürk, Şahinde DemirciAbstract:In modern urban atmosphere, sulphur dioxide (SO2) attacks calcite (CaCO3) in calcareous stone-producing gypsum (CaSO4·2H2O) which forms crust at rain sheltered surfaces and accelerates erosion at areas exposed to rain. The airborne particles collected on stone surfaces have always been considered to enhance the gypsum crust formation and thus it is believed that they should be removed from the surface to decrease the effects of SO2. In this study, our aim was to investigate this event by carrying out a series of experiments in laboratory using pure Calcium carbonate powder to represent calcareous stone. Sodium montmorillonite, activated carbon, ferric oxide, vanadium pentoxide and cupric chloride were mixed in the pure Calcium carbonate powder as substitutes of the airborne particles in the polluted atmosphere. The samples have been exposed at nearly 10 ppmv SO2 concentrations at 90% relative humidity conditions in a reaction chamber for several days. The mineralogical composition of the exposed samples were determined by X-ray diffraction (XRD) analysis and infrared spectrometer (IR). Sulphation reaction products, Calcium Sulphite hemihydrate, gypsum and unreacted calcite, were determined quantitatively using IR. Exposed samples have also been investigated morphologically using a scanning electron microscope (SEM). Experimental results reveal that Calcium Sulphite hemihydrate is the main reaction product of the SO2–calcite reaction. It turns out that airborne particles play an important catalytic role in the oxidation of Calcium Sulphite hemihydrate into gypsum, although their presence does not very significantly affect the extent of sulphation reaction. This behaviour of airborne particles is explained by the presence of liquid film on the Calcium carbonate surface where a series of reactions in the gas–liquid–solid interfaces takes place.
Şahinde Demirci - One of the best experts on this subject based on the ideXlab platform.
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Effect of airborne particle on SO2–calcite reaction
Applied Surface Science, 1999Co-Authors: Hasan Böke, Emine N. Caner-saltik, E.hale Göktürk, Şahinde DemirciAbstract:Abstract In modern urban atmosphere, sulphur dioxide (SO2) attacks calcite (CaCO3) in calcareous stone-producing gypsum (CaSO4·2H2O) which forms crust at rain sheltered surfaces and accelerates erosion at areas exposed to rain. The airborne particles collected on stone surfaces have always been considered to enhance the gypsum crust formation and thus it is believed that they should be removed from the surface to decrease the effects of SO2. In this study, our aim was to investigate this event by carrying out a series of experiments in laboratory using pure Calcium carbonate powder to represent calcareous stone. Sodium montmorillonite, activated carbon, ferric oxide, vanadium pentoxide and cupric chloride were mixed in the pure Calcium carbonate powder as substitutes of the airborne particles in the polluted atmosphere. The samples have been exposed at nearly 10 ppmv SO2 concentrations at 90% relative humidity conditions in a reaction chamber for several days. The mineralogical composition of the exposed samples were determined by X-ray diffraction (XRD) analysis and infrared spectrometer (IR). Sulphation reaction products, Calcium Sulphite hemihydrate, gypsum and unreacted calcite, were determined quantitatively using IR. Exposed samples have also been investigated morphologically using a scanning electron microscope (SEM). Experimental results reveal that Calcium Sulphite hemihydrate is the main reaction product of the SO2–calcite reaction. It turns out that airborne particles play an important catalytic role in the oxidation of Calcium Sulphite hemihydrate into gypsum, although their presence does not very significantly affect the extent of sulphation reaction. This behaviour of airborne particles is explained by the presence of liquid film on the Calcium carbonate surface where a series of reactions in the gas–liquid–solid interfaces takes place.
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Effect of airborne particle on SO2-calcite reaction
Applied Surface Science, 1999Co-Authors: Hasan Böke, Emine N. Caner-saltik, E.hale Göktürk, Şahinde DemirciAbstract:In modern urban atmosphere, sulphur dioxide (SO2) attacks calcite (CaCO3) in calcareous stone-producing gypsum (CaSO4·2H2O) which forms crust at rain sheltered surfaces and accelerates erosion at areas exposed to rain. The airborne particles collected on stone surfaces have always been considered to enhance the gypsum crust formation and thus it is believed that they should be removed from the surface to decrease the effects of SO2. In this study, our aim was to investigate this event by carrying out a series of experiments in laboratory using pure Calcium carbonate powder to represent calcareous stone. Sodium montmorillonite, activated carbon, ferric oxide, vanadium pentoxide and cupric chloride were mixed in the pure Calcium carbonate powder as substitutes of the airborne particles in the polluted atmosphere. The samples have been exposed at nearly 10 ppmv SO2 concentrations at 90% relative humidity conditions in a reaction chamber for several days. The mineralogical composition of the exposed samples were determined by X-ray diffraction (XRD) analysis and infrared spectrometer (IR). Sulphation reaction products, Calcium Sulphite hemihydrate, gypsum and unreacted calcite, were determined quantitatively using IR. Exposed samples have also been investigated morphologically using a scanning electron microscope (SEM). Experimental results reveal that Calcium Sulphite hemihydrate is the main reaction product of the SO2–calcite reaction. It turns out that airborne particles play an important catalytic role in the oxidation of Calcium Sulphite hemihydrate into gypsum, although their presence does not very significantly affect the extent of sulphation reaction. This behaviour of airborne particles is explained by the presence of liquid film on the Calcium carbonate surface where a series of reactions in the gas–liquid–solid interfaces takes place.
E.hale Göktürk - One of the best experts on this subject based on the ideXlab platform.
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Quantification of CaCO3–CaSO3·0.5H2O–CaSO4·2H2O mixtures by FTIR analysis and its ANN model
Materials Letters, 2004Co-Authors: Hasan Böke, Serhan Ozdemir, Sedat Akkurt, E.hale Göktürk, Emine N. Caner SaltikAbstract:Abstract A new quantitative analysis method for mixtures of Calcium carbonate (CaCO 3 ), Calcium Sulphite hemihydrate (CaSO 3 ·1/2H 2 O) and gypsum (CaSO 4 ·2H 2 O) by FTIR spectroscopy is developed. The method involves the FTIR analysis of powder mixtures of several compositions on KBr disc specimens. Intensities of the resulting absorbance peaks for CaCO 3 , CaSO 3 ·1/2H 2 O and CaSO 4 ·2H 2 O at 1453, 980, 1146 cm −1 were used as input data for an artificial neural network (ANN) model, the output being the weight percent compositions of the mixtures. The training and testing data were randomly separated from the complete original data set. Testing of the model was done with successfully low-average error levels. The utility of the model is in the potential ability to use FTIR spectrum to predict the proportions of the three substances in unknown mixtures.
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Effect of some surfactants on SO2-marble reaction
Materials Letters, 2002Co-Authors: Hasan Böke, E.hale Göktürk, Emine N. Caner SaltikAbstract:In the polluted atmosphere, sulphur dioxide (SO2) reacts with calcite (CaCO3) in marble producing Calcium Sulphite hemihydrate (CaSO3·0.5 H2O) and gypsum (CaSO4·2H2O). Gypsum develops crust at rain-sheltered surfaces and then, being more soluble, accelerates erosion at areas exposed to rain. Eventually, all these lead to significant deformations in the appearance and structure of marble surfaces. Clearly, some precautions must be taken to stop or at least to slow down this deterioration process which destroys our cultural heritage. In this study, we have investigated the possibilities of preventing the SO2–marble reaction by using water-soluble surfactants: Abil Quat 3270 and Tween 20. Experiments for measuring their effects have been carried out at conditions simulating the dry deposition of SO2. Infrared spectrometry and scanning electron microscopy were used to analyze the mineralogical composition and morphology of the reaction products. The extent of sulphation reaction was calculated by determining Calcium Sulphite hemihydrate and gypsum quantitatively by an IR approach and also by weight increases observed during the progress of SO2–marble reaction. A 10% decrease is observed in the total sulphation with both surfactant applications. The results have been discussed in relation to the possible stages of sulphation reaction and surface reactions of calcite.
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Effect of airborne particle on SO2–calcite reaction
Applied Surface Science, 1999Co-Authors: Hasan Böke, Emine N. Caner-saltik, E.hale Göktürk, Şahinde DemirciAbstract:Abstract In modern urban atmosphere, sulphur dioxide (SO2) attacks calcite (CaCO3) in calcareous stone-producing gypsum (CaSO4·2H2O) which forms crust at rain sheltered surfaces and accelerates erosion at areas exposed to rain. The airborne particles collected on stone surfaces have always been considered to enhance the gypsum crust formation and thus it is believed that they should be removed from the surface to decrease the effects of SO2. In this study, our aim was to investigate this event by carrying out a series of experiments in laboratory using pure Calcium carbonate powder to represent calcareous stone. Sodium montmorillonite, activated carbon, ferric oxide, vanadium pentoxide and cupric chloride were mixed in the pure Calcium carbonate powder as substitutes of the airborne particles in the polluted atmosphere. The samples have been exposed at nearly 10 ppmv SO2 concentrations at 90% relative humidity conditions in a reaction chamber for several days. The mineralogical composition of the exposed samples were determined by X-ray diffraction (XRD) analysis and infrared spectrometer (IR). Sulphation reaction products, Calcium Sulphite hemihydrate, gypsum and unreacted calcite, were determined quantitatively using IR. Exposed samples have also been investigated morphologically using a scanning electron microscope (SEM). Experimental results reveal that Calcium Sulphite hemihydrate is the main reaction product of the SO2–calcite reaction. It turns out that airborne particles play an important catalytic role in the oxidation of Calcium Sulphite hemihydrate into gypsum, although their presence does not very significantly affect the extent of sulphation reaction. This behaviour of airborne particles is explained by the presence of liquid film on the Calcium carbonate surface where a series of reactions in the gas–liquid–solid interfaces takes place.
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Effect of airborne particle on SO2-calcite reaction
Applied Surface Science, 1999Co-Authors: Hasan Böke, Emine N. Caner-saltik, E.hale Göktürk, Şahinde DemirciAbstract:In modern urban atmosphere, sulphur dioxide (SO2) attacks calcite (CaCO3) in calcareous stone-producing gypsum (CaSO4·2H2O) which forms crust at rain sheltered surfaces and accelerates erosion at areas exposed to rain. The airborne particles collected on stone surfaces have always been considered to enhance the gypsum crust formation and thus it is believed that they should be removed from the surface to decrease the effects of SO2. In this study, our aim was to investigate this event by carrying out a series of experiments in laboratory using pure Calcium carbonate powder to represent calcareous stone. Sodium montmorillonite, activated carbon, ferric oxide, vanadium pentoxide and cupric chloride were mixed in the pure Calcium carbonate powder as substitutes of the airborne particles in the polluted atmosphere. The samples have been exposed at nearly 10 ppmv SO2 concentrations at 90% relative humidity conditions in a reaction chamber for several days. The mineralogical composition of the exposed samples were determined by X-ray diffraction (XRD) analysis and infrared spectrometer (IR). Sulphation reaction products, Calcium Sulphite hemihydrate, gypsum and unreacted calcite, were determined quantitatively using IR. Exposed samples have also been investigated morphologically using a scanning electron microscope (SEM). Experimental results reveal that Calcium Sulphite hemihydrate is the main reaction product of the SO2–calcite reaction. It turns out that airborne particles play an important catalytic role in the oxidation of Calcium Sulphite hemihydrate into gypsum, although their presence does not very significantly affect the extent of sulphation reaction. This behaviour of airborne particles is explained by the presence of liquid film on the Calcium carbonate surface where a series of reactions in the gas–liquid–solid interfaces takes place.
Vanessa Reich De Oliveira - One of the best experts on this subject based on the ideXlab platform.
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Impact of solid waste treatment from spray dryer absorber on the levelized cost of energy of a coal-fired power plant
Journal of Cleaner Production, 2017Co-Authors: Matheus De Andrade Cruz, Ofélia De Queiroz Fernandes Araújo, José Luiz De Medeiros, Rui De Paula Vieira De Castro, Gabriel Travagini Ribeiro, Vanessa Reich De OliveiraAbstract:Abstract Coal-fired power plants with semi-dry flue gas desulfurization (semi-dry FGD) system produce daily tones of ashes contaminated with Calcium Sulphite. To turn this solid waste useful (e.g. to the cement industry) and avoid landfill disposal, the present study suggests a semi-dry FGD solid waste treatment unit, that promotes the dry oxidation of Calcium sulfite to Calcium sulfate. Sizing of main equipment using pilot-plant and patents data allows economic evaluation of capital expenditure, operational and maintenance costs, and sale of the treated residue, which permits estimation of levelized cost of energy to assess the impact of the technology on the electricity price of a power plant using the proposed solid waste treatment unit. As base case, a Brazilian coal-fired power plant facing decision making process on semi-dry FGD waste destination is selected. Results demonstrate that the semi-dry FGD, without the solid treatment unit, has total levelized cost of energy increased in 0.56% (from 94.44 to 94.97 $/MWh) resulting from solids waste disposal. If the treated semi-dry FGD waste was transferred (at zero revenue) as additive to a cement industry, the levelized cost of energy of the power plant would remain approximately unchanged. This is because the increase of 0.51$/MWh resulting from the investment and operation and maintenance cost of the treatment unit is compensated by the decrease of 0.53$/MWh, in virtue of the avoided waste disposal costs. However, if the commercialization as raw material of the treated semi-dry FGD waste is considered, a reduction of 2.83 $/MWh (∼3%) on the levelized cost of energy (to 92.14 $/MWh) would occur. In both cases, the proposed treatment unit shows small impact on the total power plant levelized cost of energy, besides solving the solid management problems of landfill saturation, land use and costs related to landfill maintenance. Thus, it is adequate to implement the semi-dry FGD waste treatment unit on the power plant in question. The conclusion can be extended to plants with similar design and economic parameters.
Andrew K. Galwey - One of the best experts on this subject based on the ideXlab platform.
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The oxidation of Calcium Sulphite by Calcium nitrate
Thermochimica Acta, 1998Co-Authors: Andrew K. Galwey, Clodagh EttarhAbstract:Abstract Crushed powder mixtures of Calcium Sulphite and Calcium nitrate exhibit an exothermic reaction between 650 and 700 K. This rate process has been investigated by dynamic and isothermal DSC experiments, complemented with isothermal rate studies based on gas evolution in a vacuum apparatus, together with some product analyses. It is concluded that the overall reaction is complicated, including several concurrent contributing chemical changes, in which Sulphite oxidation to sulphate is a dominant process, accompanied by some nitrate decomposition. On heating to higher temperatures (above 800 K) a second endothermic reaction was identified as the melting and breakdown of Calcium nitrate. These processes occurred at temperatures somewhat less than those characteristic of the pure salt, possibly due to the presence of products from the first reaction including small amounts of Ca(NO 2 ) 2 . The dominant exothermic reaction was accompanied by fusion, at temperatures significantly below the melting point of either reactant. This may be due to the intermediate formation of Ca(NO 2 ) 2 , melting point 551 K, or the generation of liquid product following hydrolysis reactions with water evolved during dehydration of reactant CaSO 3 ·1/2H 2 O, with which the exothermic oxidation overlapped. This dehydration step was a precursor to Sulphite oxidation. A detailed reaction mechanism is not proposed here due to the difficulties of separating the contributions from the several probable concurrent participating reactions. The role of the fluid reactant believed to be active in the oxidation process, and containing NO − 3 , NO − 2 , SO 2− 3 and possibly SO 2− 4 , in desulphurization processes, is discussed as a possible route towards removing the precursors to acid rain from coal combustion emissions. It is known that CaCO 3 reacts with NO x to form Ca(NO 3 ) 2 . The present work identifies the liquid medium recognized in the exothermic reaction as enabling the oxidation of CaSO 3 →CaSO 4 to proceed to completion at a lower temperature than the slow and product-opposed reaction of CaSO 3 with oxygen gas. Aspects of the chemistry of this complicated reaction and its potential value in pollution abatement are discussed.
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A Kinetic and Mechanistic Investigation of the Formation of Calcium Sulphate in Reactions that may be of Use in Flue-Gas Desulphurization II. Promotion of the CaSO$_{3}$ + $\frac{1}{2}$O$_{2}$ Reaction by Alkali Metal Salts
Proceedings of the Royal Society of London. Series A: Mathematical Physical and Engineering Sciences, 1996Co-Authors: D. Carl Anderson, Andrew K. GalweyAbstract:The role of alkali cations, potassium (K + ) in particular, in promoting the reaction of Calcium Sulphite with oxygen between 823 and 923 K has been investigated. This extends our previous (part I) study of the kinetics and mechanism of this reaction in the absence of additives. Almost all the solids mixed with the reactant CaSO 3 (including K 2 SO 3 , K 2 SO 4 , Na 2 SO 4 , Rb 2 SO 4 , KI, KIO 3 , KBr and others added as 5% mass) increased both rates and extents of oxidation. The pattern of kinetic behaviour remained unchanged. As with CaSO 3 alone, the reaction was strongly deceleratory and ceased before conversion of all the reactant to CaSO 4 . It is concluded that the additive does not change the reaction mechanism but, during the oxidation process, increases the permeability to oxygen of the adherent product layer that forms a barrier between CaSO 3 and O 2 . Later recrystallization of the oxidized material makes this barrier impermeable to oxygen and reaction ceases. This increase in mobility of constituents of the product layer (particularly trans-barrier oxygen diffusion), inferred from the kinetic data, is consistent with microscopic observations which give evidence of superficial sintering of the solid. The promotional ability of each additive is, therefore, determined by a balance between enhanced ease of transport across the barrier and the diminution of rate that results from crystallite growth through sintering. This qualitatively accounts for the observed pattern of reaction rates and the relatively large variations in the activation energies calculated for similar rate processes. It is concluded that the inefficient use of CaCO 3 in flue gas desulphurization, whereby a proportion of the calcite remains unreacted, is a consequence of the strongly adherent barrier layer of product formed. This layer is not easily removed or suitably modified by additives to remove the inhibition. The most useful route to effective employment of the solid is to diminish particle sizes sufficiently (probably to crystallite edge lengths of less than 0.3 μm) to avoid limitation of the extent: of reaction by the product CaSO 4 barrier.
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a kinetic study of the thermal dehydration of Calcium Sulphite hemihydrate
Canadian Journal of Chemistry, 1992Co-Authors: Carl Anderson, Andrew K. GalweyAbstract:An isothermal kinetic study of the dehydration of orthorhombic Calcium Sulphite hemihydrate is reported:Fractional reaction (α)–time curves exhibit the sigmoid shape characteristic of nucleation and growth reactions proceeding in the solid state. Yield–time data exhibit a very satisfactory obedience to the Avrami–Erofe'ev (n = 2) equationRate studies were concerned with the temperature interval 573–673 K and the calculated activation energy was 173 ± 8 kJ mol−1, showing the hydrate to be thermally relatively stable. The mechanism of dehydration is discussed and reference is made to the dehydration of Calcium hydroxide with which it shows close similarities.
