SOUTHERN JOURNAL OF SCIENCES

A new phase of the (CuAlSe₂)_1-x(TaSe)_x alloy system was synthesized by the melt and annealingtechnique and studied by SEM, DTA, and XRPD techniques. Its structure has been refined by the Rietveld methodusing X-ray powder diffraction data. The new alloy corresponds with the stoichiometry Cu_0.4Al_0.3TaSe₂. Thiscompound crystallizes in the hexagonal space group 𝑃6ത𝑚2 (Nº 187) with a MoS₂-type structure, and unit cellparameters a = 3.455(2) Å, c = 13.423(4) Å, V = 138.7(1) Å3, Z =2. The crystal structure is based on the MoS₂-type of stacking of TaSe₂ layers with a partial ordering of Cu and Al cations over the tetrahedral sites. The powderpattern was composed of 63.1% of the principal phase Cu_0.4Al_0.3TaSe₂ and 29.9% of CuAlSe₂, 7.0% of TaSe₃, asthe secondary phases. 

Carbon capture and storage (CCS) has been observed as an alternative measure to mitigate emissions from greenhouse gases. CCS systems separate CO₂ during the process of converting fuel and transport to the facilities where they are stored, e.g., under geological formation conditions. Capture and sequestration technologies are now widely used in different industries. CO₂ capture is currently a costly and energy-consumingtechnology. The costs obviously depend on the size of the plant and the type of fuel used. Generally, capture systems are categorized into three categories: pre-combustion, post-combustion, and oxy-fuel combustion. The saline aquifer, depleted oil, and gas fields are large-capacity storage sinks. The coalbeds also provide as a substitute to geological storage. One of the main advantages of coal storage is renewable methane fuel and coaldesulfurization. The studied coal reserves are located in Candiota, State of Rio Grande do Sul, Brazil. These are the largest coal deposits in the country, with a reserve of 1 billion tons. This work will represent a study on CO₂ storage in Candiota coalbed system. The use of a synthetic CO2 cylinder with a flow of 0.2 L/min varies the time of contact with the coalbed. The results from the volatile matter increase by 11%. The results of the ultimate analysis exhibited an 8% increase for carbon and oxygen after 60 minutes of CO₂ flow in the coalbed. On the other hand, there was a reduction of 32% for sulfur. The resultant phenomena occur due to the adsorption capacity of CO₂, where the compounds are released from the pores of coal.

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The ore beneficiation process uses little technology, but mining companies have high economic performance. As an energy source, firewood plays a fundamental role due to its simple storage, low cost, great availability of forests, and lack of processing. Thus, the present work aims to analyze the consumption of firewood as fuel and possible improvements in the process for the production of lime in terms of harnessing raw materials and costs. Calcium oxide is obtained from the thermal decomposition of calcium and magnesium carbonates obtained from dolomitic deposits of limestone (CaCO₃ : CaMgCO₃). After CaO extraction, it is subjected to a calcination process, removing carbon dioxide (CO₂) in ovens that work at temperatures between 900 and 1200°C. The source of energy applied to the calcination furnaces in the analyzed area is wood. The wood has a calorific value between 2,250 and 2,700 Kcal/Kg, but the moisture content responsible for the thermal variation must be considered. The firewood burning process was carried out in a ravine type oven where the temperature at which operators are exposed to heat was evaluated. The results indicated that the cooking time dropped by 20% as the amount of wood is fed into the oven. This increase represents a significant gain in lime production, thus leading to a higher profit for the company.  

Introduction: Thermal insulating coatings are increasingly being introduced into construction practice for internal and external finishing enclosing structures and pipelines. Thermal insulation coatings are usually made based on polymer binder and mineral fillers. The durability and stability of the properties of heat-insulating materials depend on the type of binder. As a rule, polymers are used as a binder: epoxy resin; silicone rubber; urea-formaldehyde resins; aqueous dispersed polymers - styrene-butadiene, polyvinyl acetate, and acrylate (acrylic and styrene-acrylic). The quality indicator of binders can be assessed by the influence of the seasonality of climatic impact, and as a result, the best elastic strength characteristics of binders can be established after one month to a year of field tests. Aim: To determine the influence of climatic factors on the change in the elastic-strength indicators of epoxy polymers binders used in liquid thermal insulation coatings. Methods: A tensile testing machine of the AGS-X series with the TRAPEZIUM X software was used for mechanical tests. The tests were carried out in accordance with GOST 11262-2017 (ISO 527-2: 2012) "Plastics. Tensile test method". Results and Discussion: The paper discusses the results of experimental studies of the compositions of polymer binders and their resistance to various climatic factors, which will later be used as a polymer binder for thermal insulation coatings based on fine mineral granular systems. Conclusions: When analyzing the changes in the characteristics of polymer samples after exposure to climatic factors, it was found that compositions based on Etal-247 epoxy resin, cured with amine hardeners Etal-1440N, Etal-1460, Etal-1472, and Etal-45M, demonstrate the best elastic strength characteristics after one year of full-scale tests. The high stability of the indicators under consideration allows us to conclude that the use of Etal-247 resin as a base leads to creating of the most climate-resistant epoxy coatings.

Background: The Araucaria angustifolia is a prominent tree species indigenous to the southern regions of Brazil. The tree can be a source of different compounds of interest if properly used. Aims: This research aims to compare the alcoholic extraction of compounds from Araucaria angustifolia using two different methods, microwave-assisted extraction and maceration extraction. Methods: Alcahoolic extractions of compounds from the sawdust of Araucaria angustifolia were performed using microwave-assisted extraction and maceration extraction. The color was observed by eye inspection. The taste was observed by putting the samples into the mouth and tasting it. The olfactive test was conducted at hot and cold temperatures. Results: it was obtained red color solution, both from the bark and from the branch. The intensity of the color changed with the extraction method and time of maceration. The solutions tasted like "green wood". Discussion: MAE and Maceration extraction can provide extracts from the bark and branch of the araucaria tree. There is the possibility that the “green wood” taste of the MAE extract can be changed with the thermal treatment of the wood. Conclusions: microwave-assisted extraction can perform the faster extraction of compounds from Araucaria angustifolia than maceration extraction.