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In this work, we developed an efficient absorbent material pellet-based made of calcium oxide to capture part of the CO2 emitted by motor vehicles, to obtain an innovative technology for controlling the emission of greenhouse gases. Problems with CO2 capture efficiency using CaO was solved after modifications with carbon nanotubes (CNTs) that improve CaO adsorbent porosity leading high CO2 capture efficiency (98.2%). The CO2 gas adsorption by pellet was followed by thermogravimetric analysis showed that porosity generated promoted a better CO2 adsorption compared to unmodified CaO (64.1%). The results strongly suggest that the preparation of CaO pellet-based in the presence of a small amount of nanotubes (0.05%), followed by calcination, promotes the formation of channels that allow to substantially improve CO2 capture capacity by increasing the exposing adsorbent calcium species. This effect may be due to the crystallite size of the materials. The calcium oxide, after modification with carbon nanotubes, showed particle size values of 25 and 17 nm, respectively, before and after calcination.

Unfortunately the surname of the fifth author is wrongly published in the original article as Patricia P. de Souza instead of Patricia S. O. Patricio

The present work deals with an efficient synthesis of calcium hydroxide-based materials modified with magnesium oxide and ammonium phosphate for Calcium Looping technology in Post-combustion CO2 capture. This modification produced 3 %wt of struvite, MgNH4PO4·6H2O, and hydroxyapatite Ca10(PO4)6(OH)2, in the material. These minerals are very hard, which contributes to increase the mechanical strength of the materials. The modified materials are four times more resistant to impact and abrasion than materials containing pure calcium hydroxide freshly prepared, and therefore, can generate less fractures and dusts. In addition, struvite and hydroxyapatite can create open pores and channels into the sorbent structure when they release water or ammonia by thermal decomposition above 200 °C identified by X-ray microtomography. Due to this porous structure the materials are more resistant to sintering during absorption/regeneration cycles. The new developed absorbent are harder, less brittle, generate less frictional dust, and are more resistant to high temperature sintering (400–700 °C) compared to pure Ca(OH)2 based materials. The results showed that calcium hydroxide modified materials can be considered highly efficiency to CO2 absorption, with particular achievement of greater than 50%wt.

In the aluminum industries, there are several steps involved in processing since the extraction of bauxite to obtain the final product (Al). During the development of these, various steps generated wastes. One of them, from the electrostatic filter of the calcination step of the Bayer process is a very fine black powder, rich in alumina (Al2O3) that does not meet industry specifications, and it is discarded in the industry yard. Alumina is a noble material and has high commercial value. This black powder has great prospects for recovery, recycling, and future applications. Therefore, it is important to perform characterization of tailings and to do that we have used XRD, SEM, EDS, FTIR, Raman, and thermal analysis.

FT-Raman spectroscopy has been used for the analytical characterization of the Parmotrema tinctorum Del. Ex Nyl . lichen. Lecanoric acid, the major lichen chemical present in the total mass, has been extracted from the lichen, purified and characterized by Raman spectroscopy supported by means of theoretical DFT calculations. The calculations indicate that the aromatic ring A of the lecanoric acid structure is kept in the molecular plane by a strong hydrogen bond between the ortho -hydroxyl group of ring A and the ester group; this hydrogen bond is shorter in the C1 isomer form, which is the main feature responsible for the Gibbs free energy difference (−2.96 kcal/mol) favouring the C1 isomer. In spite of the similarity of possible conformers and although many of the predicted Raman bands are found to be common for both forms, there is one Raman transition very characteristic of structure C2, centred at 1815 cm −1 , assigned to the stretching of the C O group of the ester moiety ( ν (C O,ester)). For the isomer C1 this transition was predicted at 1729 cm −1 , with a lower frequency ascribed to the stronger hydrogen bond present in the latter conformation. In the experimental spectrum two strong bands are found at 1654 and 1638 cm −1 (shoulder) attributed to the C O stretching mode. The analysis of the normal modes for the corresponding transitions calculated at 1742 and 1729 cm −1 allowed the assignment to be made to ν (C O) from the carboxylic acid and ester moiety, respectively. Most of the other Raman bands were also assigned by comparison with the theoretical model. The Raman spectrum obtained directly from the P. tinctorum lichen shows a remarkable similarity with the isolated lecanoric acid spectrum, as well as the presence of bands at 1529 and 1156 cm −1 which are characteristic of a carotenoid species. The results confirm the potential of Raman spectroscopy for taxonomic characterization of lichen species.

Neste trabalho foi realizada a caracterização química e mineralógica de uma amostra da rocha esteatito da Mina de Mostardas, Nova Lima, MG. Brasil. Os resultados demonstraram que o esteatito é composto de aproximadamente 65 % m/m de talco, 29 % m/m de clinocloro, 5 % m/m de anfibólios (tremolita e actinolita) e 1 % m/m de óxidos de ferro e piroxênio. Como o talco é uma carga mineral tradicionalmente usada na indústria, o esteatito foi aplicado em diversas formulações de espumas flexíveis de poliuretano substituindo-se parcialmente o reagente poliol, a fim de baratear os custos e melhorar as propriedades mecânicas do polímero. Os estudos de reatividade demonstraram que o polímero não interage com a superfície do mineral por ligações covalentes, mas apenas interage fracamente por ligações de van der Waals. As imagens de microscopia eletrônica de varredura indicam uma possível interação entre o polímero e o mineral talco. Os compósitos esteatito/poliuretano flexível apresentaram um aumento no fator de conforto e na resistência à compressão das espumas em relação às espumas convencionais de poliuretano flexível, indicando um aumento do suporte de carga e aumento do conforto dos compósitos. A composição química e o comportamento térmico das espumas não foram significativamente afetados pela adição de esteatito às formulações convencionais de poliuretano flexível. This work was focused on the chemical and mineralogical characterization of a steatite rock sample from the Mostardas Mine, in Nova Lima, state of Minas Gerais, Brazil. Results showed that steatite sample is composed of approximately 65% w/w talc, 29% w/w clinochlore, 5% w/w amphibole (tremolite and actinolite) and 1% w/w ofiron oxides and pyroxene. As talc is a mineral filler commonly used in industry, steatite was used in various formulations of flexible polyurethane foams partially replacing the polyol reagent in order to lower costs and improve the mechanical properties of the polymer.The reactivity studies showed that the polymer does not interact with the surface of the mineral by covalent bonds; it interacts only weakly via van der Waals bonds. The images of scanning electron microscopy indicate a possible interaction between the polymer and talc. The composites steatite/flexible polyurethane showed an increase in comfort factorand in the compressive strength of the foam, it compared to conventional flexible polyurethane foams, indicating an increase in load support and in comfort, provided by the composites. The chemical composition and thermal behavior of the foams were not significantly affected by steatite addition in polymer.

This work describes the synthesis of composites steatite/flexible polyurethane by replacing 4.5 wt. % of polyol with steatite rock powder. We evaluated two mechanical properties of composites (comfort factor and support factor) for various formulations based on a fractional factorial design. The new synthesized composites showed higher support factor, greater comfort factor, and lower cost, compared to conventional flexible polyurethane foams. There is not a significant change in the chemical composition of the foams, due to substitution of 4.5 wt. % polyol by steatite. However, there was a decrease in cell size and greater interaction between the hard segments of the composite.