scholarly journals THERMODYNAMIC LAWS OF CHROMIUM REDUCTION BY MIXTURES OF СН4 + Н2О AND СН4 + СО2

2020 ◽  
pp. 20-29
Author(s):  
Oleksandr Gryshyn ◽  
Angela Nadtochij ◽  
Nataliia Velykonska ◽  
Yevhenii Zykin
Keyword(s):  
Chromium Oxide ◽  
Reduction Potential ◽  
Solid Phase ◽  
Raw Materials ◽  
Recovery Process ◽  
Partial Replacement ◽  
Technological Basis ◽  
Phase Reduction ◽  
High Reduction ◽  
Reduction Of Oxides

The development of a physico-chemical model of methane behavior in the processes of solid-phase reduction of chromium-containing raw materials will allow us to create the technological basis for the production of multicomponent sponge ligatures. The reduction of oxides with methane is accompanied by the deposition of soot carbon. The negative effect of carbon black, which is blocking the reaction surface, can be eliminated by adding carbon dioxide or water vapor to methane. A thermodynamic analysis of the reduction of chromium oxide with mixtures of CH4-CO2, CH4-H2O was carried out. The effect of the partial replacement of methane by carbon on the thermodynamic preferences of the process is analyzed. A physicochemical model of the behavior of the CH4 molecule in the recovery process is proposed. The thermodynamic features of reduction at various ratios of СН4 are considered: (Н2О, СО2, О2), as well as the composition of the mixture (Н2О+СО2+О2), which ensure the conditions of solid-phase reduction of oxides and the product of carbide destruction. The use of CH4 + H2O + O2 mixtures in the reduction of chromium oxide is thermodynamically less effective. The use of a mixture of СН4 + Н2О + СО2 has a very insignificant effect on the conversion of methane, and also reduces the thermodynamic preference for the reduction of Cr2O3 in comparison with СН4 + Н2О + О2 and СН4 + Н2О. However, it should be noted that in addition to CO and H2, carbon can be present in the reduction products, so the high reduction potential in this process variant (C+CO+H2) can be used to reduce oxides. The reduction of chromium oxide with mixtures of СН4 + Н2О + О2, СН4 + Н2О, and СН4 + Н2О + СО2 can be thermodynamically realized in the temperature range excluding the melting of the charge. As a result of this process, a carbide phase is formed, as well as a gas phase, which has a high reduction potential and can be used in further technological schemes. Meanwhile, it seems possible to control the carbon content in the sponge ligature by selecting the optimal composition of the source gas mixture.

scholarly journals Experimental Evaluation of Recycled Aggregates, Washing Water and Cement Sludge Recovered from Returned Concrete

2021 ◽  
Vol 12 (1) ◽  
pp. 36
Author(s):  
Alessandra Diotti ◽  
Luca Cominoli ◽  
Giovanni Plizzari ◽  
Sabrina Sorlini
Keyword(s):  
Solid Phase ◽  
Raw Materials ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Experimental Program ◽  
Innovative Technology ◽  
Technical Standards ◽  
Washing Process ◽  
Concrete Production ◽  
Washing Water

In this paper, a new innovative technology for the treatment of returned concrete is proposed. This method is based on the application of physical–mechanical processes that allow to obtain new quality products: recycled aggregates, microfiltered water and cement sludge. Specifically, by means of a mechanical system equipped with buffer and Archimedes screws, fine (d < 5 mm) and coarse (d > 5 mm) aggregates are obtained. The water coming from the washing process is sent to a microfiltration process, where a filter membrane separates the liquid phase (microfiltered water) from the solid phase (cement sludge) and no type of potentially toxic additive is added. In this context, this paper investigates the feasibility of using all these components as new raw materials for sustainable concrete production. In particular, according to the requirements imposed by technical standards, an experimental program was developed, aimed at evaluating the physical, chemical, and mechanical properties of the analyzed materials. The results showed that both recycled aggregates, the microfiltered water and the cement sludge can be used to produce new structural concrete. In particular, it was proven that also the cement sludge, which generally represents the most critical component destined for disposal, can be reused as filler in the partial replacement of sand.

scholarly journals Influence of Cu on the Improvement of Magnetic Properties and Structure of L10 FePt Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1097
Author(s):  
Luran Zhang ◽  
Xinchen Du ◽  
Hongjie Lu ◽  
Dandan Gao ◽  
Huan Liu ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Annealing Temperature ◽  
Reduction Method ◽  
Solid Phase ◽  
Average Particle Size ◽  
Fept Nanoparticles ◽  
Average Particle ◽  
Phase Reduction ◽  
Different Temperatures ◽  
One Step

L10 ordered FePt and FePtCu nanoparticles (NPs) with a good dispersion were successfully fabricated by a simple, green, one-step solid-phase reduction method. Fe (acac)3, Pt (acac)2, and CuO as the precursors were dispersed in NaCl and annealed at different temperatures with an H2-containing atmosphere. As the annealing temperature increased, the chemical order parameter (S), average particle size (D), coercivity (Hc), and saturation magnetization (Ms) of FePt and FePtCu NPs increased and the size distribution range of the particles became wider. The ordered degree, D, Hc, and Ms of FePt NPs were greatly improved by adding 5% Cu. The highest S, D, Hc, and Ms were obtained when FePtCu NPs annealed at 750 °C, which were 0.91, 4.87 nm, 12,200 Oe, and 23.38 emu/g, respectively. The structure and magnetic properties of FePt and FePtCu NPs at different annealing temperatures were investigated and the formation mechanism of FePt and FePtCu NPs were discussed in detail.

scholarly journals Fe3O4@C Nanoparticles Synthesized by In Situ Solid-Phase Method for Removal of Methylene Blue

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 330
Author(s):  
Hengli Xiang ◽  
Genkuan Ren ◽  
Yanjun Zhong ◽  
Dehua Xu ◽  
Zhiye Zhang ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Solid Phase ◽  
Raw Materials ◽  
Phase Method ◽  
Maximum Adsorption Capacity ◽  
High Catalytic Activity ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
High Concentrations

Fe3O4@C nanoparticles were prepared by an in situ, solid-phase reaction, without any precursor, using FeSO4, FeS2, and PVP K30 as raw materials. The nanoparticles were utilized to decolorize high concentrations methylene blue (MB). The results indicated that the maximum adsorption capacity of the Fe3O4@C nanoparticles was 18.52 mg/g, and that the adsorption process was exothermic. Additionally, by employing H2O2 as the initiator of a Fenton-like reaction, the removal efficiency of 100 mg/L MB reached ~99% with Fe3O4@C nanoparticles, while that of MB was only ~34% using pure Fe3O4 nanoparticles. The mechanism of H2O2 activated on the Fe3O4@C nanoparticles and the possible degradation pathways of MB are discussed. The Fe3O4@C nanoparticles retained high catalytic activity after five usage cycles. This work describes a facile method for producing Fe3O4@C nanoparticles with excellent catalytic reactivity, and therefore, represents a promising approach for the industrial production of Fe3O4@C nanoparticles for the treatment of high concentrations of dyes in wastewater.

Chromium oxide pigments

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Gerhard Pfaff
Keyword(s):  
Thermal Stability ◽  
Chromium Oxide ◽  
Building Materials ◽  
Solid Phase ◽  
Oxide Hydrate ◽  
Application Systems ◽  
Ammonium Dichromate ◽  
Green Pigments

Abstract The chromium(III) oxide pigments Cr2O3 (chromium oxide green) and CrOOH (chromium oxide hydrate green) are representatives of the inorganic green and blue–green pigments. Cr2O3 pigments are very important for the coloration of paints, coatings, plastics, building materials and other application systems. CrOOH pigments have lost their technical importance because of the low thermal stability. Chromium oxide green pigments are characterized by excellent application properties. They are synthesized starting from alkali dichromates or ammonium dichromate by reduction in liquid or solid phase.

Microstructure and Mechanical Properties of ZrB2/h-BN Multiphase Ceramics by Low-Temperature Reactive Sintering

2016 ◽  
Vol 697 ◽  
pp. 510-514 ◽  
Author(s):  
Feng Rui Zhai ◽  
Ke Shan ◽  
Ruo Meng Xu ◽  
Min Lu ◽  
Zhong Zhou Yi ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Relative Density ◽  
Fracture Strength ◽  
Solid Phase ◽  
Raw Materials ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Microstructure And Mechanical Properties ◽  
Multiphase Ceramics ◽  
Strength And Toughness

In the present paper, the ZrB2/h-BN multiphase ceramics were fabricated by SPS (spark plasma sintering) technology at lower sintering temperature using h-BN, ZrO2, AlN and Si as raw materials and B2O3 as a sintering aid. The phase constitution and microstructure of specimens were analyzed by XRD and SEM. Moreover, the effects of different sintering pressures on the densification, microstructure and mechanical properties of ZrB2/h-BN multiphase ceramics were also systematically investigated. The results show that the ZrB2 was obtained through solid phase reaction at different sintering pressures, and increasing sintering pressure could accelerate the formation of ZrB2 phase. As the sintering pressure increasing, the fracture strength and toughness of the sintered samples had a similar increasing tendency as the relative density. The better comprehensive properties were obtained at given sintering pressure of 50MPa, and the relative density, fracture strength and toughness reached about 93.4%, 321MPa and 3.3MPa·m1/2, respectively. The SEM analysis shows that the h-BN grains were fine and uniform, and the effect of sintering pressure on grain size was inconspicuous. The distribution of grain is random cross array, and the fracture texture was more obvious with the increase of sintering pressure. The fracture mode of sintered samples remained intergranular fracture mechanism as sintering pressure changed, and the grain refinement, grain pullout and crack deflection helped to increase the mechanical properties.

scholarly journals Characterization of Volatile Compounds of Bulgur (Antep Type) Produced from Durum Wheat

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Saad Ibrahim Yousif ◽  
Mustafa Bayram ◽  
Songul Kesen
Keyword(s):  
Durum Wheat ◽  
Volatile Compounds ◽  
Solid Phase ◽  
Raw Materials ◽  
Production Method ◽  
Volatile Flavor Compounds ◽  
Volatile Flavor ◽  
Production Techniques ◽  
Gas Chromatography Mass Spectroscopy

Bulgur is enjoyed and rediscovered by many people as a stable food because of its color, flavor, aroma, texture, and nutritional and economical values. There is more than one type of bulgur overall the world according to production techniques and raw materials. The volatile compounds of bulgur have not been explored yet. In this study, Headspace Solid Phase Microextraction (HS-SPME) and Gas Chromatography–Mass Spectroscopy (GS-MS) methods were used to determine the volatile flavor compounds of bulgur (Antep type, produced from Durum wheat). Approaching studies were used and the results were optimized to determine the ideal conditions for the extraction and distinguish the compounds responsible for the flavor of bulgur. Approximately, 47 and 37 important volatile compounds were determined for Durum wheat and bulgur, respectively. The study showed that there was a great diversity of volatiles in bulgur produced using Durum wheat and Antep type production method. These can lead to a better understanding of the combination of compounds that give a unique flavor with more researches.

scholarly journals Incorporation of sugarcane bagasse ash waste as an alternative raw material for red ceramic

Cerâmica ◽  
2013 ◽  
Vol 59 (351) ◽  
pp. 473-480 ◽  
Author(s):  
K. C. P. Faria ◽  
J. N. F. Holanda
Keyword(s):  
Sugarcane Bagasse ◽  
Raw Materials ◽  
Phase Evolution ◽  
Linear Shrinkage ◽  
Raw Material ◽  
Partial Replacement ◽  
Clay Material ◽  
Natural Clay ◽  
Materials Used ◽  
Sugarcane Industry

The sugarcane industry generates huge amounts of sugarcane bagasse ashes (SCBA). This work investigates the incorporation of a SCBA waste as an alternative raw material into a clay body, replacing natural clay material by up to 20 wt.%. Clay ceramic pieces were produced by uniaxial pressing and fired at temperatures varying from 700 to 1100 ºC. The technological properties of the clay ceramic pieces (linear shrinkage, apparent density, water absorption, and tensile strength) as function of the firing temperature and waste addition are investigated. The phase evolution during firing was followed by X-ray diffraction. The results showed that the SCBA waste could be incorporated into red ceramics (bricks and roofing tiles) in partial replacement for natural clay material. These results confirm the feasibility of valorisation of SCBA waste to produce red ceramic. This use of SCBA can also contribute greatly to reducing the environmental problems of the sugarcane industry, and also save the sources of natural raw materials used in the ceramic industry.

scholarly journals Determination of pesticide residues by chromatographic methods for food safety

2021 ◽  
Vol 12 (3) ◽  
pp. 111-118
Author(s):  
N. Yu. Tereshchenko ◽  
◽  
O. Yu. Kursenko ◽  
O. I. Khyzhan ◽  
O. I. Khyzhan ◽  
...  
Keyword(s):  
Plant Extract ◽  
High Performance ◽  
Solid Phase ◽  
Raw Materials ◽  
Apple Fruit ◽  
Raw Material ◽  
Benzimidazole Derivatives ◽  
Quantitative Composition ◽  
Variable Component ◽  
Selective Solvents

The paper presents the methodology of preparation of samples of oilseeds, lettuce, apples for research by chromatographic control of xenobiotics of the following chemical groups of pesticides: benzimidazole derivatives, anilinopyrimidine derivatives, bipyridylium derivatives. The implementation of the following processes is considered: homogenization of the sample, purification of the extract by solid-phase or liquid-liquid extraction, obtaining a plant extract, obtaining an extract of analytes. For fine-grained homogenized samples of sunflower seeds, the optimal ratio of raw material -extragent is 1:20, for pasty homogenized samples of apple fruit - 1:10, for liquid samples of homogenized lettuce - 1: 5. Analysis of the distribution of xenobiotics in the system octane/water, the dipole moment of solvents allowed to determine the extractants that are able to dissolve and remove xenobiotics from raw materials. It was found that a mixture of acetonitrile and methanol (4: 1) should be used to remove benzimidazole derivatives and anilinopyrimidine derivatives, bipyridylium derivatives are best extracted with methanolic trifluoroacetic acid (9.5: 0.5). Quantitative analysis of xenobiotics content in extracts obtained from samples artificially enriched with xenobiotics was performed. The most complete xenobiotics were removed from samples of plant products containing traces of fat. The most difficult process of sample preparation is the process of obtaining sunflower seed extract. The content of xenobiotics in extracts obtained from samples artificially enriched in analytes is influenced by the temperature at which the process takes place and the duration of extraction. Based on the chemical composition of the sample matrix and the list of analytes, the conditions of the variable component of the methodology are proposed: obtaining plant extract under the action of selective solvents, homogenized raw material-solvent with constant stirring of the extraction system at 180-200 rpm, or under the action of ultrasonic vibrations with a frequency of 37 kHz from 4°C to 25°C for 5-25 minutes. The control of the qualitative and quantitative composition of the studied plant extracts and analyte extracts was investigated by the methods of high-performance liquid and gas chromatography (liquid and gas) with mass-selective detectors.

scholarly journals PROPRIEDADES DE ARGAMASSAS COM EVA (ETHYLENE VINYL ACETATE) EM SUBSTITUIÇÃO PARCIAL AO AGREGADO

2017 ◽  
Vol 13 (1) ◽  
Author(s):  
Cleidson Carneiro Guimarães ◽  
Érica Souza Andrade
Keyword(s):  
Vinyl Acetate ◽  
Industrial Waste ◽  
Raw Materials ◽  
Ethylene Vinyl Acetate ◽  
Project Managers ◽  
Partial Replacement ◽  
Construction Sector ◽  
Cement Ratio ◽  
Aggregate Content ◽  
Hardened State

RESUMO: O setor da construção civil apresenta grande potencial para aproveitamento de vários tipos de resíduos industriais. A incorporação dos resíduos, principalmente nas argamassas e concretos, produtos com vasta aplicabilidade no setor, tem se mostrado como uma ótima alternativa na diversificação das matérias-primas e para a economia de recursos naturais. Esse trabalho avaliou as propriedades das argamassas, no estado fresco e endurecido, produzidas com substituição parcial da areia por resíduo de EVA (Ethylene Vinyl Acetate). Para isso, foram preparadas argamassas com teores de substituição do agregado 0% (referência), 5%, 10% e 15%, em massa. A relação água/cimento, para cada traço, foi determinada empiricamente e mantida constante para as argamassas com substituição. Os resultados apontam que as argamassas produzidas com agregado de EVA apresentam menor absorção de água e também um decréscimo da resistência mecânica. Desta forma, a produção de argamassas utilizando EVA em substituição ao agregado natural é viável, todavia é necessário avaliar os parâmetros mínimos de aplicação para cada finalidade. Dessa forma, o trabalho apresenta contribuição ao servir de suporte a gestores de empresas de argamassas ou gestores de obra a tomarem decisões acerca da inserção do resíduo de EVA na produção de argamassa. ABSTRACT: The construction sector has great potential for use of various types of industrial waste. The incorporation of waste, especially in mortar and concrete products with wide applicability in the industry, has proven to be a great alternative for diversification of raw materials and the economy of natural resources. This study evaluated the properties of mortars in fresh and hardened state, made with partial replacement of sand by waste EVA (Ethylene Vinyl Acetate). For this, mortars were prepared with substitution aggregate content 0%(reference), 5%, 10% and 15% by weight. The water / cement ratio for each trace has been empirically determined and maintained constant for the mortars with replacement. The results show that the mortars produced with EVA aggregate have lower water absorption and also a decrease in the mechanical strength. Thus, the production of mortar using EVA instead of natural aggregate is feasible, however, it is necessary to evaluate the minimum parameters for each application purpose. Thus, the work presents contribution to provide support for the mortar company managers or project managers make decisions about the insertion of EVA residue in the production of mortar.

scholarly journals Improving the marmalade technology by adding a multicomponent fruit-and-berry paste

2021 ◽  
Vol 6 (11 (114)) ◽  
pp. 6-14
Author(s):  
Olga Samokhvalova ◽  
Kateryna Kasabova ◽  
Nataliа Shmatchenko ◽  
Aleksey Zagorulko ◽  
Andrii Zahorulko
Keyword(s):  
Mass Fraction ◽  
Dry Matter ◽  
Nutritional Value ◽  
Raw Materials ◽  
Partial Replacement ◽  
Black Currant ◽  
Reducing Substances ◽  
Improved Technique ◽  
Improved Technology ◽  
Functional Components

The necessity to optimize the nutritional value of marmalade by using physiologically functional ingredients containing vitamins, dietary fiber, minerals, and other useful substances in its composition has been substantiated. Specifically, using the multicomponent fruit-and-berry paste from apples, quince, black currant has been proposed, which is obtained by an improved technique. The technique is characterized by the rapid dehydration (30...45 s, at 50 °C) of the blended paste in a rotor plant to 28...30 % of dry matter. When studying the dependences of the effective viscosity of paste compositions on the shear rate, it was found that the paste that demonstrated the best indicators contained apple in the amount of 40 %; quince ‒ 50 %; black currant ‒ 10 %. It has been experimentally proven that the rational amount of fruit-and-berry paste is 30 % with a decrease in agar by 30 %. This makes it possible to obtain the jelly-fruit marmalade on agar with a mass fraction of moisture of 18 %, a total acidity of 10 degrees, and a mass fraction of reducing substances not more than 28 %. The products have a sweet-sour taste, with a pleasant aftertaste and the smell of black currant, rich purple color, jelly-like form, and non-tight consistency. The strength of the new samples of marmalade with a decrease in the amount of agar is 18.9 kPa, similar to that of control. The improved technology makes it possible to expand the range of "healthy products", which is achieved by the partial replacement of raw materials with a fruit-and-berry paste, which contains a significant number of physiologically functional components. This allows for an increase in the nutritional value of marmalade, as well as a decrease in the formulation amount of agar, which is expensive, by 30 %. In addition, gentle concentration modes improve the process of paste making

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