Mass Ratio Of Ca Research Articles

Experimental Research on the Compression Property of Geopolymer Concrete with Molybdenum Tailings as a Building Material

This paper experimentally studied the effects of different molybdenum tailings (MoT) content, standard curing and 60 °C water curing conditions on the compressive strength of fly ash-based geopolymers at different ages. X-ray diffraction (XRD), scanning electron microscopy/energy dispersive spectrometer (SEM/EDS) and Fourier-transform infrared spectroscopy (FTIR) were applied to investigate the effect of the content of MoT and different curing conditions on the reaction products, microstructure and chemical composition of fly ash-based geopolymers. The results show that MoT content and curing conditions have synergistic effects on the compressive strength of fly ash-based geopolymers. For standard curing, the increase in MoT content is detrimental to the development of compressive strength, and an obvious weak interfacial transition zone between MoT and the gel product is observed in specimen containing 40 wt% MoT; meanwhile, under water curing conditions, the compressive strength of geopolymers first increases and then decreases with the increase in MoT, and the 28-day compressive strength can reach 90.3 MPa when the content of MoT is 10 wt%. The SEM results show that the curing conditions have a great influence on the microstructure of the geopolymer matrix, and the microstructure of the specimens under the water curing conditions is smoother and denser, with fewer pores. EDS analyses show that the gel product constituting the geopolymer matrix is N(C)-A-S-H gel; MoT can participate in the reaction, and the mass ratio of Ca/(Si + Al) of N(C)-A-S-H gel increases with the increase in MoT, resulting in a decrease in compressive strength. In addition, the results of the FTIR confirm that water curing can increase the degree of crosslinks in the gel phase.

Frost Resistance and Mechanism of Circulating Fluidized Bed Fly Ash-Blast Furnace Slag-Red Mud-Clinker Based Cementitious Materials.

The motivation of this work is to enhance the long-term frost resistance of circulating fluidized bed fly ash (CFA)-based multisolid waste cementitious material (CSM). In this research, CSM2 is prepared by 30 wt.% CFA, 20 wt.% blast furnace slag (BFS), 10 wt.% red mud (RM), 10 wt.% phosphorus slag (PS), and 30 wt.% cement clinker (CC). The strength and mass of CSM are detected by a press and electronic balance. The hydration products, polymerization degree, thermogravimetric, micromorphology, pore structure, and harmful element leaching are detected by XRD, MAS NMR, TG-DTG, SEM-EDX, MIP, and ICP-MS. The major findings indicate that the strength loss, mass loss, and strength of CSM2 after 25 freeze–thaw cycles (CSM2-25) are 2.35%, 0.36%, and 49.95 MPa, respectively, which is superior to other CSMs and still meets the performance requirements of fly ash Portland cement 42.5#. The main hydration products are C-S-H gel, C/N-A-S-H gel, and ettringite during the freeze–thaw cycle. The polymerization degree and thermogravimetric loss of hydration products in CSM2-25 are 50.65% and 12.82 wt.%, respectively, which are higher than those of other CSMs under the synergy of CFA, BFS, RM, and PS. In addition, the microscopic results show that the interface between the paste and aggregate, micromorphology, and pore structure of CSM2-25 are the densest when the mass ratio of Ca/(Si + Al) is 0.81. These characteristics are beneficial to the improvement of long-term frost resistance in CSM2. Finally, the leaching results of harmful elements in CSM2 after 25 freeze–thaw cycles still meet the WHO standard of drinking water. Therefore, this work provides a reliable reference for the preparation of green cementitious materials with great frost resistance by using CFA, BFS, RM, and PS.

A new process for extracting vanadium by direct calcification using the heat of molten vanadium slag

A novel technology for extracting vanadium from molten converter vanadium slag was studied at the laboratory scale by oxidation and calcification. The effect of the cooling method, CaO addition, and reaction time on the phases of calcified vanadium slag was studied. Under the action of oxygen and CaO, the molten vanadium slag underwent calcification reaction to form acid-soluble calcium vanadate phase and the feasibility of its main chemical reaction was calculated by Factsage8.1. The calcified vanadium slag was leached by H2SO4 solution and characterized by the XRF, XRD, SEM, and EDS techniques. Compared with the traditional process, the new process saved much energy, and it was faster and more efficient. The XRD results showed that CaV2O5, Ca7V4O17, and Ca3V2O8 were gradually formed in the molten vanadium slag with increasing CaO addition. However, when too much CaO was added, Ca2SiO4 and CaTiO3 were also formed. These phases wrapped part of the vanadium and reduced the leaching rate of vanadium. When the mass ratio of Ca to V was 0.75, under the optimal acid leaching conditions (particle size of calcified vanadium slag less than 0.075 mm, leaching temperature 90 ?, H2SO4 concentration 200 g.L-1, liquid-to-solid ratio 6:1 ml.g-1, leaching time 60 min, and stirring speed 300r.min-1), the leaching rate of vanadium from calcified vanadium slag could exceed 90%. The new process not only saved energy and reduced emissions, but also reached the average level of the existing vanadium extraction process.

Utilization of porous carbon synthesized with textile wastes via calcium acetate template for tetracycline removal: The role of template agent and the formation mechanism

A porous carbon obtained from cotton/polyester textile wastes was synthesized by the calcium acetate template method. This research studied the effect of preparation conditions and evaluated the characterization of porous carbon, and further explored its formation mechanism. The porous carbon possessed a high specific surface area of 1106.63 m2/g under an optimum condition (pyrolysis temperature = 800 °C, mass ratio of CA: CPW = 1.5:1, pyrolysis time = 1.5 h). It was found that calcium acetate played the role of catalyst to promote the degradation of cotton/polyester textile. CaCO3 and CaO fabricated by calcium acetate acted as the template to generate a mesoporous structure. The generated CO2 etched carbon skeleton to create a large number of micropores. Besides, it was supported as the carbon source to fuse with carbon structures, further consolidating the aromatic structures of porous carbon. The optimized porous carbon has a high adsorption capacity of 506.40 mg/g for tetracycline. And the adsorption data fitted better by the first-pseudo-order model and Langmuir isotherms with an endothermic and spontaneous adsorption process. The cotton/polyester-based porous carbon was a promising economical material for tetracycline.

Effect of Plant Biostimulants on Macronutrient Content in Early Crop Potato Tubers

This paper analyzes the effects of the foliar application of the seaweed extracts Bio-algeen S90 (Ascophyllum nodosum) and Kelpak SL (Ecklonia maxima), as well as the humic and fulvic acids in HumiPlant (leonardite extract) on the macronutrient content in tubers of very early potato cultivars (‘Denar’, ‘Lord’, ‘Miłek’) and their ionic ratios. The field experiment was carried out in central-eastern Poland over three growing seasons, using Haplic Luvisol. The biostimulants were applied according to the manufacturers’ recommendations. Potatoes were harvested 75 days after planting. The use of biostimulants increased potassium (K) content in tubers, on average, by 1.26 g∙kg−1 of dry matter compared with the untreated control tubers. Bio-algeen S90 did not affect the phosphorus (P) content in tubers, whereas Kelpak SL and HumiPlant reduced the phosphorus content, on average, by 0.063 g∙kg−1 of dry matter. The biostimulants did not affect calcium (Ca), magnesium (Mg), or sodium (Na) content in tubers. The use of biostimulants resulted in an increase in the mass ratios of K+:Ca2+, K+:Mg2+, and (K+ + Na+):(Ca2+ + Mg2+) in early crop potato tubers, compared with the untreated control tubers, but did not affect the mass ratios of Na+:Ca2+ and Na+:Mg2+ or the mass ratio of Ca:P. The macronutrient content in early crop potato tubers and their ionic ratios depended on the cultivar and environment conditions.

In situ synthesis of three-dimensional graphene skeleton copper azide with tunable sensitivity performance

In this work, a series of three-dimensional graphene skeleton copper azide (3D GS@CA) composites with tunable sensitivity performance is designed by using 3D graphene as a skeleton and in situ azidation of Cu nanoparticles under NH3 atmosphere. In this architecture, CA particles uniformly distributed in the 3D graphene skeleton can effectively prevent the aggregation of CA and inhibit CA grains forming a sea urchin-like structure during azidation. The CA maintained a smooth surface that can ensure the appropriate mechanical sensitivity. Owing to unique transport properties, the 3D graphene network interconnected with CA nanoparticles enables better contact between them, thereby facilitating heat transfer during the reaction and accelerating thermal decomposition of CA. In addition, the electrostatic sensitivity of 3D GS@CA also shows significant improvement by easily tuning the mass ratio of CA in the composite. Given these advantages, 3D GS@CA as a primary explosive exhibited great potential application in miniaturized explosive systems.

Effect of organic phase change material and surfactant on HCFC141b hydrate nucleation in quiescent conditions

The effects of organic phase change material (PCM) and surfactant on HCFC141b hydrate nucleation are investigated under quiescent conditions. The surfactants Tween80 and Span80 are chosen as emulsifiers, and the mixture of PCM n-decanoic acid (CA) and dodecyl alcohol (DE) is used as promoter. The emulsion of HCFC141b + CA–DE (the mass ratio of CA to DE is 1:1) + Tween80 or Span80 + H2O is prepared, where CA–DE is dispersed in water and HCFC141b is dissolved into CA–DE. The hydrophobic CA–DE droplets create an increased local HCFC141b concentration, and organize the surrounding water into a clathrate-like structure. Additives of 1 wt% CA–DE and 1 wt% Tween80 have the best promotion effect on the nucleation of HCFC141b hydrate. The nucleation of HCFC141b hydrate has a stochastic nature and the additives (CA–DE, Tween80 and Span80) reduce the scatter of the induction time of HCFC141b hydrate formation.

High-Efficiency CaO-Based Sorbent Modified by Aluminate Cement and Organic Fiber Through Wet Mixing Method

CaO-based sorbents are usually used for high-temperature postcombustion CO2 capture through cyclic carbonation–calcination reactions. However, the rapid decay of sorbent reactivity limits their application. In this study, three types of CO2 sorbent precursors, namely Ca(CH3COO)2, Ca(OH)2, and CaCO3, are used to produce initial CaO-based sorbents. Then, the initial sorbents are mixed with aluminate cement and organic fibers at an appropriate ratio to synthesize high-efficiency sorbents. Our results show that the cyclic performance of the sorbent that decomposed from Ca(CH3COO)2 is better than that decomposed from Ca(OH)2 and CaCO3. It is mainly because the sorbent pore structure becomes much developed after Ca(CH3COO)2 decomposition. Furthermore, when mixed with aluminate cement, the CaO-based sorbent achieves a good performance for CO2 capture because of the formation of the sorbent skeleton Ca12Al14O33. For example, when the mass ratio of Ca(OH)2 to aluminate cement is set as 1:1, CaO conversion achieves...

Capric acid/intercalated diatomite as form-stable composite phase change material for thermal energy storage

Leakage issue and low thermal conductivity largely restrict feasibility of fatty acid in real application of thermal energy storage (TES). In this paper, a novel form-stable phase change material (FSPCM) capric acid/diatomite (CA/DT) for TES was prepared using direct impregnation method by using CA as PCM and diatomite as supporting material. The fabricated composites were investigated in detail via the leakage test to determine the optimization proportion, and the real mechanism of preventing leakage by diatomite was analyzed. The characterization techniques such as thermogravimetric analysis, differential scanning calorimetry, intelligent paperless recorder technology, Fourier transform infrared spectrometer and scanning electron microscopy were applied to systematically investigate the thermal properties, microstructure and thermal compatibility of the prepared composites. The results showed that the maximum mass ratio of CA adsorbed into DT without leakage is as high as 50 mass%, which is mainly ascribed to the porous structure of DT. The selected FSPCM has a melting point of 34.9 °C and latent heat of 89.2 J g−1. What is more, the CA/DT FSPCM exhibits a distinctly enhanced thermal stability by TG analyses. The heat transfer efficiency of the CA/DT FSPCM is higher than that of pristine CA. Due to the high adsorption capacity, high latent heat, good thermal stability as well as low cost, the CA/DT FSPCM can be considered as potential materials for thermal energy storage.

Response of spring wheat to NPK and S fertilization. The content and uptake of macronutrients and the value of ionic ratios

Abstract The aim of the study was to evaluate the effect of nitrogen (N) and sulphur (S) fertilizers on the content and uptake of macronutrients by grain dry mass (DM) of spring wheat. A field experiment was conducted in southeastern Poland on Cambisols (WRB 2007), in conditions of low S content in the soil. The experiment included 2 factors: fertilization with N (0, 40, 80, 120 kg ha-1) and with S (0, 50 kg ha-1). The experiment showed a positive response of spring wheat to N and S fertilization. The highest grain yield was found after application of 80 kg N ha-1 and addition of 50 kg S ha-1 (5.43 t ha-1). The described combination resulted in beneficial content of phosphorus (P), potassium (K), magnesium (Mg), calcium (Ca) (P –4.267, K–4.533, Mg–1.567, Ca–0.433 g kg-1) and uptake of macroelements by grain dry mass (DM) (P–20.48, K–21.79, Mg–7.52, Ca–2.08 kg ha-1). A generally positive correlation was found between content and uptake of macronutrients with exception of P content. Fertilization with N caused significantly narrowed mass ratios of K+: Ca2+, K+: Mg2+ and mass and mole ratio of K+:(Ca2++Mg2+) and increased mass ratio of Ca:P. While S application narrowed significantly, mass ratios of K+:Ca2+ and K+: (Ca2+ + Mg2+) and increased mass ratio of Ca:P.

The Properties of Heightened Temperature Curing Steel Slag

Orthogonal tests were conducted in this paper to study the mechanical properties of the heightened temperature curing steel slag (SS)-ground blast furnace slag (GBFS) cementitious materials without clinker based on four factor: A) the mass ratio of SS/GBFS; B) the mixing milling time of the cementitious materials; C) the mass ratio of Ca(OH)2/gypsum (from flue gas desulfurization waste, FGDW); D) curing temperature. The hydration products and microstructure of the heightened temperature curing SS-GBFS system was also studied. When the four factors are 1:2, 480 m2 kg-1, 2:1 and 35 oC, respectively, the highest compressive strength was observed with the values of 18.36 MPa, 26.89 MPa and 45.32 MPa at the ages of 3 days, 7 days and 28 days, respectively. The influence of the four factors on the mechanical properties is in the order of D > A > B > C. The results from X-ray diffraction (XRD) and scanning electron microscope (SEM) indicate that ettringite and C-S-H form from the reactions between C2S from SS and amorphous phases from GBFS, and FGDW during hydration, which greatly contributes to the early-age strength. As the curing time increases, more ettringite forms due to the reaction of SO42- from FGDW, OH- from Ca(OH)2 and AlO2- from GBFS, and the formed ettringite (AFt) intervened with C-S-H gels, which provides the framework of the microstructure and thus improves the strength of the specimens.

Preparation and properties of caprylic-nonanoic acid mixture/expanded graphite composite as phase change material for thermal energy storage

Summary To satisfy the application demands for latent heat storage in the temperature range from 5°C to 15°C, an original composite phase change material (PCM), CA-NA/EG (caprylic-nonanoic acid/expanded graphite), was prepared and characterized. For CA-NA/EG, the mass ratio of CA and NA was 8:2, and the mass percentage of the CA-NA in CA-NA/EG composite PCM was determined as 90% by leakage test. The melting and freezing points of the CA-NA/EG were 6.84°C and 9.34°C, and corresponding latent heats were 108.75 kJ/kg and 107.67 kJ/kg. In addition, its thermal conductivity, thermal stability and reliability were investigated by thermal conductivity apparatus (TCA), thermal gravimetric analyzer (TGA), and accelerated thermal cycle test for 100 melt/freeze cycles, respectively. The results showed that the CA-NA/EG had a good thermal stability and an excellent thermal reliability. Moreover, the thermal conductivity of CA-NA/EG had an improvement of 25% than that of the CA-NA. On the other hand, the accelerated thermal cycle test also indicated that the CA-NA/EG had no supercooling during all melt/freeze cycles. Therefore, the prepared composite PCM, CA-NA/EG, can be applied for low-temperature thermal energy storage owing to its proper melting temperature, acceptable latent heat and thermal conductivity, excellent thermal stability and reliability.

Highly Nitrogen-Doped Porous Carbon Obtained Using Nicotinic Acid by a Template Carbonization Approach for Supercapacitors

Nitrogen-enriched porous carbon materials have been successfully synthesized via a template carbonization method, in which nicotinic acid acts as carbon/nitrogen sources, and Ca(OAc)[Formula: see text]H2O as a template. It reveals that the mass ratio of Ca(OAc)[Formula: see text]H2O-to-nicotinic acid and the carbonization temperature dominate the morphology of carbon materials as well as capacitive performances. The sample obtained with the ratio of Ca(OAc)[Formula: see text]H2O-to-nicotinic acid as 1.5 at 800[Formula: see text]C, namely the C-1.5-800 sample, displays the optimum capacitive behavior. It is amorphous with low-graphitization degree, possessing hierarchical porous structure, high nitrogen content (14.5%), large specific surface area (788[Formula: see text]m2 g[Formula: see text]) and high total pore volume (3.56[Formula: see text]cm3 g[Formula: see text]). As a result, the as-made C-1.5-800 electrode exhibits a maximum specific capacitance of 216[Formula: see text]F g[Formula: see text] at a current density of 1[Formula: see text]A g[Formula: see text] in 6[Formula: see text]M KOH aqueous solution. It also displays a maximum energy density of 45.9[Formula: see text]Wh kg[Formula: see text] at 2050[Formula: see text]W kg[Formula: see text] and a maximum power density of 20100[Formula: see text]W kg[Formula: see text] at 19.2[Formula: see text]Wh kg[Formula: see text] at operation temperature of 50[Formula: see text]C in [EMIm]BF4/AN organic electrolyte. More importantly, the C-1.5-800 electrode exhibits an excellent cycling stability within 5000 cycles at 5[Formula: see text]A g[Formula: see text]. This work may enrich and broaden the field of porous carbon and its potential application for supercapacitors under high temperature.

Operculum bone carp (cyprinus carprio sp.) scaffold is a new potential xenograft material: a preliminary study

Orbital floor fracture with extensive bone loss, would cause herniation of the orbital tissue into the maxillary sinus. Graft implantation should be done on the orbital fracture with extensive bone loss. Different types of grafts have their own characteristics and advantages. Xenograft has been widely studied for use in bone defects. This study was to investigate cyprinus carprio sp. opercula bone as a potential xenograft. The aim of this study was to investigate based on EDS chemical analysis using a ZAF Standardless Method of Quantitative Analysis (Oxide) and SEM examination conducted in the laboratory of Mathematics, Institute of Technology Bandung. Particularly the mass ratio of Ca and P (5.8/3:47), the result is 1.67. This is equivalent to the stoichiometric Hydroxyapatite (HA) (Aoki H, 1991, Science and medical applications of hydroxyapatite, Tokyo: Institute for Medical and Engineering, Tokyo Medical and Dental University). C N O that there is an element of protein/amino acid collagen compound, serves as a matrix together with HA. As shown in the SEM analysis that the matrix is a porous sheet-shaped (oval) that interconnect with each other, which is good scaffold. The pore is composed of large pores >200 microns and smaller pores between the large pores with a size smaller or equal to 10 microns that can serve for the attachment of osteoblast cell. In conclusion, Opercula bone carp (cyprinus carprio sp.) scaffold could be a new potential xenograft material.

Reaction mechanisms of low-grade molybdenum concentrate during calcification roasting process

The effects of Ca-based additives on roasting properties of low-grade molybdenum concentrate were studied. The results show that calcium-based additives can react with molybdenum concentrate to form CaSO4 and CaMoO4. The initial oxidation temperature of MoS2 is 450 °C, while the formation of CaMoO4 and CaSO4 occurs above 500 °C. The whole calcification reactions are nearly completed between 600 and 650 °C. However, raising the temperature further helps for the formation of CaMoO4 but is disadvantageous to sulfur fixing rate and molybdenum retention rate. Calcification efficiency of Ca-based additives follows the order: Ca(OH)2>CaO>CaCO3. With increasing the dosage of Ca(OH)2, the molybdenum retention rate and sulfur-fixing rate rise, but excessive dosages would consume more acid during leaching process. The appropriate mass ratio of Ca(OH)2 to molybdenum concentrate is 1:1. When roasted at 650 °C for 90 min, the molybdenum retention rate and the sulfur-fixing rate of low-grade molybdenum concentrate reach 100% and 92.92%, respectively, and the dissolution rate of molybdenum achieves 99.12% with calcines being leached by sulphuric acid.

A capric–palmitic–stearic acid ternary eutectic mixture/expanded graphite composite phase change material for thermal energy storage

This paper demonstrated a capric acid–palmitic acid–stearic acid ternary eutectic mixture/expanded graphite (CA–PA–SA/EG) composite phase change material (PCM) for low-temperature heat storage. The CA–PA–SA ternary eutectic mixture with a mass ratio of CA:PA:SA=79.3:14.7:6.0 was prepared firstly, and its mass ratio in the CA–PA–SA/EG composite can reach as high as 90%. The melting and freezing temperatures of CA–PA–SA/EG composite were 21.33°C and 19.01°C, and the corresponding latent heat were 131.7kJkg−1 and 127.2kJkg−1. The CA–PA–SA/EG composite powders can be formed into round blocks by dry pressing easily, with much higher thermal conductivity than CA–PA–SA. Thermal performance test showed that the increasing thermal conductivity of CA–PA–SA could obviously decrease the melting/cooling time. Thermal property characterizations after 500 heating/cooling cycles test indicated that CA–PA–SA/EG composite PCM had excellent thermal reliability. Based on all these results, CA–PA–SA/EG composite PCM is a promising material for low-temperature thermal energy storage applications.

Comparison of test methods to assess pozzolanic activity

Assessment of the pozzolanic activity of cement replacement materials is increasingly important because of the need for more sustainable cementitious products. The pozzolanic activity of metakaolin , silica fume , coal fly ash, incinerated sewage sludge ash and sand have been compared using the Frattini test, the saturated lime test and the strength activity index test. There was significant correlation between the strength activity index test and the Frattini test results, but the results from these tests did not correlate with the saturated lime test results. The mass ratio of Ca(OH) 2 to test pozzolan is an important parameter. In the Frattini test and strength activity index test the ratio is approximately 1:1, whereas in the saturated lime test the ratio is 0.15:1. This explains why the saturated lime test shows higher removal of Ca(OH) 2 and why the results from this test do not correlate with the other test methods.

Fly Ash Penetration through Electrostatic Precipitator and Flue Gas Condenser in a 6 MW Biomass Fired Boiler

The effects of an electrostatic precipitator and a flue gas condenser on size resolved fly ash particle concentration and composition were studied in a 6 MW biomass combustion unit, fired with moist forest residue. The boiler was of moving grate type. The fly ash particles were sampled upstream and downstream of the electrostatic precipitator and flue gas condenser, respectively. Fine particle number size distributions were measured using an electric mobility spectrometer (SMPS) and coarse particle number size distributions were measured using a time-of-flight instrument (APS). The mass size distributions were measured using a multi-jet low pressure cascade impactor (DLPI). For chemical analyses of the impactor substrates particle induced X-ray emission analysis (PIXE) was used. After the flue gas passed the electrostatic precipitator (ESP), the fly ash particle concentration was reduced by approximately 96% by number and 83% by mass. After the particles passed the flue gas condenser, particle number concentration was only marginally altered, whereas the mass concentration was reduced by half. Both the ESP and the condenser showed, size dependent particle separation efficiency. The main elements (Z > 12) in the fine fly ash fraction were K, S, and Cl, whereas the main elements in the coarse fraction were Ca, K, S, and Cl. After passing the ESP the mass ratio of Ca decreased in the coarse fraction, while the ratios of K, S, and Cl increased, indicating transference of fly ash material from the fine to the coarse particle fraction. There was no significant difference in the elemental composition for any particle size fraction sampled upstream or downstream of the condenser.

Improved heat resistance of Mg-Al alloys by the Ca addition

The addition of Ca into Mg-(3–9)wt%Al alloys increased the hardness at the high temperatures up to 350°C. In particular, this was remarkable when the mass ratio of Ca to Al was higher than 0.8, probably owing to the precipitation of the Mg 2 Ca phase in the alloys. Such alloys with the Ca/Al mass ratio higher than 0.8 showed excellent heat resistance at a moderate temperature. Therefore, they were considered to be the new promising light-weight heat-resistant alloys for interior automotive applications.