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Calcium Oxide (calcium + oxide)
Selected AbstractsApplication of the random pore model to the carbonation cyclic reactionAICHE JOURNAL, Issue 5 2009Gemma Grasa Abstract Calcium oxide has been proved to be a suitable sorbent for high temperature CO2 capture processes based on the cyclic carbonation-calcination reaction. It is important to have reaction rate models that are able to describe the behavior of CaO particles with respect to the carbonation reaction. Fresh calcined lime is known to be a reactive solid toward carbonation, but the average sorbent particle in a CaO-based CO2 capture system experiences many carbonation-calcination cycles and the reactivity changes with the number of cycles. This study applies the random pore model (RPM) to estimate the intrinsic rate parameters for the carbonation reaction and develops a simple model to calculate particle conversion with time as a function of the number of cycles, partial pressure of CO2, and temperature. This version of the RPM model integrates knowledge obtained in earlier works on intrinsic carbonation rates, critical product layer thickness, and pore structure evolution in highly cycled particles. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Synthesis and characterization of imidazolinium surfactants derived from tallow fatty acids and diethylenetriamineEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 10 2008Divya Bajpai Abstract This paper describes the synthesis of long-chain dialkylamido imidazolines based on tallow fatty acids and diethylenetriamine, followed by their quaternization. Imidazolines were obtained by non-solvent microwave synthesis using calcium oxide as support, which were then quaternized by using dimethyl sulfate as a quaternizing agent and iso -propanol as a solvent, to produce cationic imidazolinium salts. The synthesized cationic imidazoline surfactants were evaluated for yield and cationic content. The instrumental techniques, viz. FT-IR and 1H-NMR, verified the formation of imidazolines and their subsequent quaternization. The surface-active and performance properties of the cationic imidazolines in terms of critical micelle concentration, surface tension, dispersibility, emulsion stability, softening, rewettability and antistatic properties were also reported. [source] Aza-MIRC Reactions of Sulfonyl-Activated Hydroxycarbamates with ,,,-Difunctionalised AcrylatesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 23 2003Stefania Fioravanti Abstract Highly functionalised aziridines are readily obtained in high yields (up to 95%) under mild conditions from the reaction of trisubstituted olefins bearing different groups with nosyloxycarbamates in the presence of calcium oxide. We propose a possible explanation for the different reactivities observed between these olefins and the aminating agents. Reagent-controlled stereoselective amination reactions led to the expected products with high conversions and purities. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Early pyrotechnology in the Near East: Experimental lime-plaster production at the Pre-Pottery Neolithic B site of Kfar HaHoresh, IsraelGEOARCHAEOLOGY: AN INTERNATIONAL JOURNAL, Issue 6 2008Y. Goren A characteristic hallmark of the Pre-Pottery Neolithic B (PPNB) in the southern Levant was the extensive use of lime plaster for architectural and other purposes. Yet no obvious kilns have been identified in archaeological contexts. Here we present details of an experimental pit-kiln modeling lime-plaster production based on observed burnt stone accumulations in pits at the PPNB site of Kfar HaHoresh in the lower Galilee. The experimental kiln was loaded in layers with ,500 kg of limestone (pebbles and stones) and ,1000 kg of fuel (branches and dung). Fired for 24 hours, and reaching a maximum 870°C, the kiln yielded almost 250 kg of quicklime (calcium oxide, CaO). Micromorphological samples, general observations, and scaled plan view drawings made immediately following and nine years after ignition demonstrate that the original shape of the kiln and residual quicklime within and around it rapidly dissipated through bioturbation, trampling by animals, erosion, rain, and exposure to the elements. This could account for the seeming absence of kilns within sites, although they were probably located close to where lime-plaster was applied, given the unstable nature and toxic effects of handling quicklime. Calculations of the manpower and fuel involved indicate that PPNB lime-plaster production may have been less labor intensive and less detrimental to the environment than previously portrayed. © 2008 Wiley Periodicals, Inc. [source] Feeding value of enset (Ensete ventricosum), Desmodium intortum hay and untreated or urea and calcium oxide treated wheat straw for sheepJOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 1 2009A. Nurfeta Summary Feed intake, in vivo nutrient digestibility and nitrogen utilization were evaluated in male sheep fed different fractions (leaf, pseudostem, corm, whole plant) of enset, untreated or 2% urea- and 3% calcium oxide- (CaO or lime) treated wheat straw and Desmodium intortum hay as sole diets. All feeds, except D. intortum hay and enset leaf had low crude protein (CP) content. Non-fiber carbohydrate contents were higher in enset fractions, especially in pseudostem and corm relative to other feeds. Enset leaf and pseudostem had high calcium, phosphorus and manganese contents. Corm, whole enset and D. intortum hay were rich sources of zinc. Daily dry matter and CP intakes were higher (p < 0.05) in sheep fed D. intortum hay (830 and 133 g, respectively) than those fed pseudostem (92 and 7.8 g, respectively). Organic matter digestibilities were highest for corm (0.780) and whole enset (0.776) and lowest for D. intortum hay (0.534) and untreated wheat straw (0.522). The CP digestibility ranged from 0.636 in D. intortum hay to 0.408 in corm. Nitrogen (N) balance was highest (p < 0.05) in D. intortum hay (10.4 g/day) and lowest in corm (,1.3 g/day). Enset leaf could be a useful protein supplement whereas the pseudostem and corm could be good sources of energy. [source] Sintering Temperature Dependence of Thermoelectric Performance and Crystal Phase of Calcium Cobalt OxidesJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 10 2010Masahiro Tahashi Polycrystalline samples were synthesized by a conventional solid-state reaction. As starting materials, Co3O4 and Ca(OH)2 were mixed in a molar ratio of Ca:Co=3:4 and sintered at 1073,1373 K. The compound phases and thermoelectric properties of the resulting products were dependent on the sintering temperature. X-ray diffraction analysis showed that the Ca3Co4O9 compound was stable up to 1193 K and that Ca3Co2O6 was formed at 1273 K. At 1373 K, the sample decomposed into cobalt oxide and calcium oxide. A maximum power factor of about 100 ,W/(K2·m) at 873 K was obtained for the Ca3Co4O9 phase sintered at 1193 K. [source] Use of mixed technologies to remediate chlorinated DNAPL at a Brownfields siteREMEDIATION, Issue 3 2008David Robinson A former chlorofluorocarbon manufacturing facility in northern New Jersey was purchased for redevelopment as a warehousing/distribution center as part of the New Jersey Department of Environmental Protection's Brownfields redevelopment initiative. Soil and groundwater at the site were impacted with dense nonaqueous-phase liquids (chlorinated organic compounds) and light nonaqueous-phase liquids (petroleum hydrocarbons). The initial remedial strategy (excavation and offsite disposal) developed by prior site owners would have been cost-prohibitive to the new site owners and made redevelopment infeasible. Mixed remedial technologies were employed to reduce the cost of remediation while meeting regulatory contaminant levels that are protective of human health and the environment. The most heavily impacted soils (containing greater than 95 percent of the contaminant mass) were excavated and treated onsite by the addition of calcium oxide and lime kiln dust coupled with physical mixing. Treated soils were reused onsite as part of the redevelopment. Residual soil and groundwater contamination was treated via in situ injections of emulsified oil to enhance anaerobic biodegradation, and emulsified oil/zero-valent iron to chemically reduce residual contaminants. Engineering (cap) and administrative (deed restriction) controls were used as part of the final remedy. The remedial strategy presented in this article resulted in a cost reduction of 50 percent of the initial remedial cost estimate. © 2008 Wiley Periodicals, Inc. [source] The double-layered hydroxide 3CaO·Al2O3·0.5CaBr2·0.5CaCl2·10H2OACTA CRYSTALLOGRAPHICA SECTION C, Issue 2 2001Jean-Philippe Rapin The title compound, calcium oxide,dialuminium trioxide,calcium dibromide,calcium dichloride hydrate (3/1/0.5/0.5/10), also formulated as Ca2Al(OH)6Br0.478Cl0.522·2H2O (dicalcium aluminium hydroxide hemibromide hemichloride dihydrate), is a double-layered hydroxide which belongs to the solid solution Ca2Al(OH)6BrxCl1,x·2H2O, where x can vary from 0 to 1. Chloride and bromide anions of the negatively charged interlayer [Br0.5Cl0.5·2H2O], share statistically the same crystallographic site. Al3+ and Ca2+ cations are coordinated by six and seven O atoms, respectively. All water molecules are bonded to Ca2+ cations and assume the seventh coordination position. Anions in the interlayer are surrounded by ten H atoms. Br, and Cl, are therefore connected to the main layer by ten hydrogen bonds, six of 2.74,(2),Å and four of 2.52,(5),Å, where the donors are hydroxyl groups and water molecules, respectively. Like the chloride equivalent, the title compound is a 6R polytype with trigonal space group Rc and lattice parameters a = 5.7537,(4),Å and c = 48.108,(4),Å. [source] | ||||||||||||||||