Mole Ratio Of Ca Research Articles

Maximizing the red emission of CaCO3:Eu3+ phosphors by using a Taguchi L9 orthogonal design

This work reports the structural, morphological and luminescent properties of CaCO3:Eu3+ phosphors synthesized by a precipitation method. Those phosphors were made under different conditions such as: mole ratio for Ca:CO3 (1:1, 1:2 and 1:3), pH (from 7 to 11), temperature (from 25 to 75 °C) and Eu3+ concentration (from 1 to 5 at.%). We used a Taguchis’ design (orthogonal L9 array) to find the optimum conditions that allow the synthesis of CaCO3:Eu3+ phosphors with the highest red emission intensity. After this, only 9 samples were synthesized. According to the X-ray diffraction patterns, all the samples presented a mixture of vaterite and calcite phases. Different morphologies were also observed by scanning electron microscopy such as porous microspheres, stacked pillars, microbelts or coalesced particles. We also measured the photoluminescence (PL) spectra for these 9 samples and calculated their integrated PL intensity. Those values were used as input in the ANOVA analysis, which was employed to find the critical parameters that affect the emission intensity of the samples. As a result, we found that the temperature and the mole ratio of Ca:CO3 are the most influential factors on the luminescent properties. We also employed the McCamy formula to calculate the correlated color temperature (CCT) and obtained values in the range of 1763–2797 K, which correspond to warm lighting sources. Moreover, the phosphor with the highest orange/red emission intensity presented a color purity of 96.66%, which is close to that used by the National Television Standard Committee (NTSC). Hence, the results presented here demonstrated that the CaCO3:Eu3+ phosphors could be used as a red-emitting component in White LEDs excited with UV chips.

Fabrication and Characterization of Porous Bioceramic Made from Bovine Bone Powder Mixed Calcium Phosphate Glass

Bovine bone xenograft was selected bioactive material currently widespread acceptable for using as human bone void filler. In this paper we described a new porous bioceramic block fabricated from bovine bone powders mixed with calcium phosphate glass. The characterized methods were atomic absorption spectrometer, x-ray diffraction, scanning electron microscope, energy dispersion x-ray spectroscopy, diffusion test, bending test, compressive test and Archimedes’ principle. The final products showed interconnecting pores size range 100 to 500 mm, apparent porosity about 52% and mole ratio of Ca:P as 1.65. The toxic elements such as arsenic, cadmium, mercury, and lead were lower standard limits of ASTM I (American Society for Testing and Materials International). The samples had a compressive strength more than 400 kg/cm2. So, this object can be useful as an alternative choice for human bone substitute in the vertical compression load bearing area.

Calcium soap from palm fatty acid distillate for ruminant feed: Ca(OH)2 as calcium source

PFAD can be utilized as raw material for producing calcium soap, a kind of ruminant feed supplement. It gives benefits to the ruminants’ health and increases the quantity and quality of cattle’s milk. This research evaluated the effect of stoichiometric mole ratio of Ca(OH)2 to PFAD and water temperature on calcium soap production using PFAD and calcium hydroxide as raw materials by applying modified fusion method. The result showed that the acid value of products decreased as the mole ratio of Ca(OH)2 to PFAD increased and the low water temperature lowered the acid value of products. The highest fatty acid conversion (98%) was achieved at the stoichiometric mole ratio of 3. However, the use of such high mole ratio is not preferable because the product will have excessive calcium, which may disturb the absorption of other minerals in ruminant’s digestion. Thus, further research related to operating condition and the use of other calcium sources in the calcium soap production is still required.

Mechanism of chromium oxidation by alkali and alkaline earth metals during municipal solid waste incineration

The influence of alkali and alkaline earth metals on the formation of hexavalent chromium (Cr(VI)) during municipal solid waste (MSW) incineration has drawn much attention due to the high toxicity of Cr(VI). In the present work, the distribution of Cr(VI) in MSW incineration ash residues sampled from various plants was measured. The results show that the oxidation of chromium in combustion process is determined by the content of free CaO (f-CaO) in the MSW and is facilitated by alkali metal compounds at lower temperatures in the flue gas cooling process. In some cases, the content of f-CaO is low during MSW incineration, and the oxidation of Cr2O3 in the case of low mole ratio of Ca and Cr was investigated. The mixture of CaO and Cr2O3 was heated at temperatures ranging from 973 to 1373K and the oxidation of Cr2O3 was detected by determining the consumption of oxygen in the carrier gas using an online mass spectrometer. According to the results, more chromium is oxidized in the thermally treated mixture at 1173K than at higher temperatures. At 1173K, part of chromium is oxidized to form CaCrO4 and the unoxidized chromium remains in the form of Cr2O3. In contrast, Cr2O3 is prior to form Ca3(CrO4)2 at higher temperatures and the unoxidized chromium is mostly transformed into CaCr2O4. Compared with Cr2O3, CaCr2O4 is more easily oxidized by CaO or K2CO3, indicating that more Cr(VI) would be formed during MSW incineration when trivalent chromium (Cr(III)) is transformed into CaCr2O4. Measures should be taken to suppress the formation of CaCr2O4 such as the control of the operating temperature and CaO addition.

Research on the natural features of karst water, on the example of some water intakes

The existence of safe and abundant raw water sources is a priceless treasure for any country. Water resources are of particular importance for Montenegro, especially for the development of tourism and agriculture which represent the backbone of its economic development. With respect to water potential, Montenegro is at the top of Europe. However, it is not a sufficient factor, but the very way it is used and protected, as well as the improvement of its valorization. Economic development which is not based on the conservation and good governance of natural resources may have negative consequences for the overall development. The aim of the paper is the study of natural properties of karst ground waters and their changes through interrelation of some ions, as indicators, on the example of five intakes in use. The paper presents the results of the research on the said waters and the values of indicators which point to their exceptional benefits for the water supply. However, the effects of the anthropogenic factor are evident, which are reflected in the range of the mole ratio of Ca /Mg ions ranging from 5.4 to 9.6, and the values (eqv.SO4/Cl) ranging from 0.3 to 2.0. Protection of the environment, especially preservation of the quality of water resources of Montenegro, imposes the urgency of implementation of the objectives of the Water Framework Directive.

Different morphologies of ZnO nanostructures via polymeric complex sol–gel method: synthesis and characterization

Various morphologies of ZnO nanostructures, such as nanoparticles, nanorods and nanoflowers have been achieved controllably by polymeric sol–gel method. In this approach, zinc nitrate Zn(NO3)2·6H2O, citric acid and ethylene glycol were used as the source of Zn2+, the chelating agent and the solvent agent, respectively. The microstructure of the ZnO nanostructures was characterized by X-ray diffractometry, scanning electron microscopy with the energy dispersive X-ray spectroscopy, transmission electron microscopy, thermogravimetric analysis and Fourier transform infrared spectroscopy. The effect of ethylene glycol to citric acid mole ratio on the morphology and structure of the products was discussed. The ZnO nanoparticles with diameter between 24 ± 2 nm was obtained with EG:CA mole ratio equal to 2:1. The optical properties of as-obtained power were investigated by ultraviolet–visible spectroscopy.

Surface Modified CaCO<sub>3</sub> Nanoparticles with Silica via Sol-Gel Process Using in Poly(lactic acid) Nanocomposite

The goal of this work is to modify surface of calcium carbonate nanoparticles with silica (CaCO3@SiO2) via sol-gel process, and to investigate the influence of CaCO3@SiO2 on mechanical properties and fracture behavior of poly(lactic acid) nanocomposite. Modified CaCO3@SiO2 nanoparticles were prepared with different Si/Ca ratios. It is found that the Si:Ca wt% ratio was increased with respect to the Si:Ca mole ratio used in the reaction. Incorporating CaCO3@SiO2 of 5 wt% increased elastic modulus, %elongation at break and notched impact strength of PLA nanocomposites, which these properties of CaCO3@SiO2-PLA nanocomposite was increased with respect to increasing of SiO2 content on the surface of CaCO3 nano-particles. This implies that better compatibility between polymer matrix and filler was achieved after modification surface of CaCO3 with SiO2 layers.

Large Scale Synthesis of Zinc Oxide Nano- and Submicro-Structures by Pechinis Method: Effect of Ethylene glycol/Citric Acid Mole Ratio on Structural and Optical Properties

Znic oxide nano- and submicro-structures have been synthesized controllably by the polymeric precursor method (Pechini). In this approach, zinc acetate Zn(CH3COO)2.2H2O, citric acid and ethylene glycol were used as the source of Zn 2+ , the chelating agent and the connecting agent, respectively. The microstructure of the ZnO nano- and submicro-structures was characterized by X-ray diffracto- metry (XRD) and scanning electron microscopy (SEM) with the energy dispersive X-ray spectroscopy (EDX), transmission electron mi- croscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FT-IR). The effect of ethylene glycol to citric acid mole ratio on the morphology and structure of the products was discussed. Different morphologies such as nanoparticles, circu- lar and hexagonal submicro-rods was achieved by changing EG:CA mole ratio. The ZnO nano- and submicro-rods was obtained with EG:CA mole ratio equal to 4:1.The optical property was investigated by the room temperature photoluminescence (PL) spectra. Rod-like and spherical ZnO nanostructures show strong UV emission but hexagonal ZnO submicro-rods show both UV (at �384 nm) and green emission (at � 510 nm) are observed in the PL spectra.

Formation and in vitro induction ability of apatite nanobelt coating on silicon

Apatite coating with nanobelt structure was fabricated on single crystal silicon by a two-step method of electrodeposition at 1.0-2.0 mA/cm 2 with DC power and vapor-thermal treatment (VTT) at 150–180 °C for 6 h over alkali medium. Scanning electron microscopy (SEM), X-ray diffractometry (XRD), and electron diffraction spectrometry (EDS) were employed to investigate the compositions and morphologies of specimens before or after vapor-thermal treatment. The results demonstrate that nanobelt crystals of coating, 0.5-2 μm in width, 100 nm in thickness, and 6-10 μm in length, are Ca-deficient apatite (CDA) with a mole ratio of Ca to P approximately of 1.60, which shows similarity of the nanobelt coating to inorganic phase in composition and to collagen in dimension appearing in human hard tissue. Induced nucleation and growth of bone-like apatite were observed on the nanobelt after soaking in a simulated body fluid (SBF) for 6 h and for 3 d, respectively, identifying that nanobelt has good ability for induction of bone-like apatite in SBF.

Synthesis and characterization of poly(urethane‐ester)s based on calcium salt of mono(hydroxybutyl)phthalate

AbstractCalcium‐containing poly(urethane‐ester)s (PUEs) were prepared by reacting diisocyanate (HMDI or TDI) with a mixture of calcium salt of mono(hydroxybutyl)phthalate [Ca(HBP)2] and hydroxyl‐terminated poly(1,4‐butylene glutarate) [HTPBG1000], using di‐n‐butyltin‐dilaurate as catalyst. About six calcium‐containing PUEs having different composition were synthesized by taking the mole ratio of Ca(HBP)2:HTPBG1000:diisocyanate (HMDI or TDI) as 3:1:4, 2:2:4, and 1:3:4. Two blank PUEs were synthesized by the reaction of HTPBG1000 with diisocyanate (HMDI or TDI). The polymers were characterized by IR, 1H NMR, Solid state 13C‐CP‐MAS NMR, TGA, DSC, XRD, solubility, and viscosity studies. The Tg value of PUEs increases with increase in the calcium content and decreases with increase in soft segment content. The viscosity of the calcium‐containing PUEs increases with increase in the soft segment content and decreases with increase in the calcium content. X‐ray diffraction patterns of the polymers show that the HMDI‐based polymers are partially crystalline and TDI‐based polymers are amorphous in nature. The dynamic mechanical analysis of the calcium‐containing PUEs based on HMDI shows that with increase in the calcium content of polymer, modulus (g′ and g″) increases at any given temperature. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1720–1727, 2006

Enzymatic incorporation of capric acid into a single cell oil rich in docosahexaenoic acid and docosapentaenoic acid and oxidative stability of the resultant structured lipid

Lipase-assisted acidolysis of a single cell oil rich in docosahexaenoic acid (DHA, C22: 6 n−3) and docosapentaenoic acid (DPA, C22:5 n−6), commerically known as the OMEGA-GOLD oil, with capric acid (CA, C10:0) was carried out. Screening of five commercially available lipases was carried out for oil to CA mole ratio of 1:3 at a temperature of 45 °C, a reaction time of 24 h, 4% (w/w of substrates) PS-30 lipase from Pseudomonas sp. and 2% (w/w of substrates and enzyme) water content. Stereospecific analysis indicated that CA was present mainly in the sn-1,3 positions of the triacylglycerol (TAG) molecules while DHA and DPA were mainly esterified to the sn-2 position. Enzymatically modified oil generally had higher conjugated diene (CD) and 2-thiobarbituric acid (TBA) values than its unmodified counterpart. However, the oil subjected to the same reaction steps in the absence of any enzyme, exhibited a significantly ( p<0.05) lower oxidative stability. Therefore, removal or alteration of endogenous antioxidants during the process may be primarily responsible for the compromised stability of the modified oil.

Synthesis and characterization of calcium containing poly(urethane-ether)s

Calcium containing poly(urethane-ether)s (PUEs) were synthesized by the reaction of hexamethylene diisocyanate or toluylene 2,4-diisocyanate (HMDI or TDI) with a mixture of calcium salt of mono(hydroxybutyl)phthalate [Ca(HBP) 2] and polyethylene glycol (PEG 200 or PEG 400). A series of calcium containing PUEs having different composition were synthesized by taking the mole ratio of Ca(HBP) 2:PEG 200 or PEG 400:diisocyanate (HMDI or TDI) as 3:1:4, 2:2:4 and 1:3:4 to study the effect of calcium content on the properties of the copolymer. The structure of the polymers were confirmed by IR, 1H-NMR, 13C-NMR, and solid state 13C-CP-MAS NMR. The polymers were soluble in dimethyl sulfoxide and dimethyl formamide. The initial decomposition temperature of the polymers decreases with increase in calcium content. The T g value of PUEs increases with increase in calcium content and decreases with increase in soft segment content and length. A single T g value is observed for the calcium containing PUEs based on PEG 200 shows the presence of homogeneous phase. However, two T g values for the PUEs based on PEG 400 for various composition of Ca(HBP) 2, PEG 400 and diisocyanate (HMDI or TDI) shows the presence of heterogeneous phase. The viscosity of the calcium containing PUEs increases with increase in the soft segment content as well as its length and decreases with increase in calcium content. X-ray diffraction patterns of the polymers show that the HMDI based polymers are partially crystalline and TDI based polymers are amorphous in nature. The dynamic mechanical analysis of the calcium containing PUEs based on HMDI shows that at any given temperature modulus ( g ′ and g ″) increases with increase in the ionic content in the polymers.

Effect of Al and Ca addition on the copper catalysed formation of silanes from Si and CH 3Cl

The effect of Al and Ca addition on formation of silanes in the Rochow Direct Process is described and discussed. The catalysts are evaluated in a stirred-bed microreactor using on-line gas chromatographic analysis. The formation of silanes from the reaction of Si and CH 3Cl is studied using a copper catalyst in the form of copper chloride. Initial tests using a typical silicon source showed that the reactor could be used to follow the consumption of Si with reproducibility of ±2%, and similar reproducibility was observed for product selectivity. The reactivity of a pure silicon and an industrial silicon sample were compared using the reactor and both samples showed identical reactivity and selectivity with respect to the amount of silicon consumed. Addition of Al metal (Cu:Al mole ratio=1.50, 0.30, 0.15) was found to significantly enhance reactivity and, to a much lesser extent, enhanced selectivity to dichlorodimethylsilane. Addition of CaCl 2 (Cu:Ca mole ratio=0.530, 0.105, 0.053) significantly decreased reactivity but had no marked effect on selectivity. Modification of the CuCl catalyst is reported in which CuCl is reacted with silanes and a form of CuCl was synthesised with significantly increased reactivity but with high selectivity to light products.

Water geochemistry of the rivers around the Taklimakan Desert (NW China): Crustal weathering and evaporation processes in arid land

Major-ion and Sr 2+ concentrations and Sr isotopic compositions of four major rivers in the Tarim Basin, NW China, were measured. These rivers in the arid lands have high total cation concentrations (TZ+) ranging from 2.3 to 46.4 meq l −1, which are significantly higher than those of the global river average (TZ+=0.725 meq l −1). Ca 2+, Mg 2+ and Na + in these rivers are the major cations, together accounting for >95% of the total cations. The total dissolved solids in the Keriya and Gaz Rivers gradually increase from their upper to lower reaches. These general features of these rivers show a strong effect of evaporation and the dissolution of the evaporates in the desert areas. The chemical and isotopic compositions of these rivers are largely controlled by the geological signatures of their drainage areas. The rivers at the northern foot of the Kunlun Mountains, an old terrain, show higher 87Sr 86Sr ratios of 0.7111–0.7154, compared to the Aksu River ( 87Sr 86Sr =0.7103−0.7105 ) draining a relatively young area. The end-member identification by the intercorrelations between chemical and isotopic ratios shows three main sources, which are derived from weathering of silicates, carbonates and evaporates. The Yurongkash River, Keriya River and the small rivers flowing from the northern foot of the Kunlun Mountains have high total ion concentrations and are characterized by high Na Ca , Mg Ca and K Ca mole ratios (1.4–30, 0.5–3.5 and 0.06–0.7, respectively), showing a strong influence of soil salts. On the other hand, the Aksu and Gaz Rivers draining regions in the western part of the Tianshan Mountains and Kunlun Mountains are dilute with respect to the amount of total dissolved solids and show low Na Ca mole ratio from 0.2 to 2, Mg Ca from 0.15 to 2 and K Ca from 0.03 to 2, suggestive of a strong influence of carbonate weathering.

Isotopic, chemical and textural relations during the experimental alteration of biogenic high-magnesian calcite

Dissolution runs with four biogenic high magnesian calcites (HMC) of different magnesium content were conducted in distilled water saturated with 100% CO 2 and 3% CO 2 at 70°C and 35°C in order to study the mechanism of alteration of HMC to low magnesian calcite (LMC). The isotopic composition ( δ 13 C and δ 18 O) of the solutions (−30%. relative to PDB and +40%. relative to SMOW, respectively) was maintained far from isotopic equilibrium with respect to the dissolving carbonate. The isotopic composition and Mg content of the residual solid phase was monitored throughout the approach to stoichiometric saturation. For the coralline algae Goniolithon, heterogeneous and possibly incongruent dissolution occurred which reduced the Mg Ca mole ratio in the solid from 0.44 to 0.26. The alteration was accompanied by an apparent isotopic equilibration of up to 20% of the solid. Runs with two littoral foraminifera, Archaias and Sorites showed a decrease in the Mg Ca mole ratio from 0.18 to 0.14 in the solid and an apparent isotopic equilibration of up to 10%. These changes began to occur before the bulk solution became saturated with respect to LMC. On the other hand the echinoid Clypeaster dissolved homogeneously and congruently with much smaller changes in magnesium and stable isotope composition: from 0.16 to 0.14 in Mg Ca mole ratio and less than 5% apparent isotopic equilibration. All isotopic shifts were in the direction of equilibrium with the solution isotopic composition. No isotopic shifts were observed in runs with Iceland spar under identical conditions. Textural differences in microstructure discovered by SEM examination of the HMC materials used suggest the possibility of an overall textural control over the observed differences in isotopic and chemical behaviour during the dissolution runs.

Time and the crystallization of apatite in seawater

Carbonate fluorapatite has been synthesized in seawater in an experiment of nearly 10-years duration. The addition of phosphate to seawater whose fluoride concentration had been increased to 7.6 mg/l brought about an initial amorphous phosphate precipitate. After 20 months, a crystalline magnesium phosphate phase developed within the amorphous phosphate. Crystallization of apatite, which occurred during the last 3 years of the experiment, was accompanied by dissolution of the crystalline magnesium phosphate phase. The MgO content of the apatite (1.9 percent) is high in comparison to Tertiary and older apatite but similar to some young apatite; the CO 2 content (3.6 percent) is medium, and the fluorine content (2.2 percent) is low but again similar to some young apatite. The hydroxyl ion (OH −) likely fills the need for additional fluorine-position atoms. The mole ratio of Ca plus substituent elements to P plus substituent elements (1.50) is low in comparison to the expected ratio of 1.67. The substitution of the hydronium ion (H 3O +) for Ca may account for this difference. The synthesis of apatite in seawater demonstrates that the factor of time overcomes the well known inhibiting effect of magnesium upon the crystallization of apatite. It also implies that given an adequate supply of phosphate, apatite can form in most ocean environments and likely plays a major pan in the control of the phosphate content of seawater.