In the Amazon, Euterpe oleracea Mart. (açaí), is part of the identity of traditional communities, and the fruit is integrated into their everyday sociocultural dynamics. Hydrolysis and pyrolysis of residual biomass can be alternatives to yield sugars, ethanol, biochar and bio-oil. The açaí seeds subjected to oxidative pretreatment followed by acid hydrolysis increased cellulose to fermentable sugars (reaching 23.5%) and second-generation ethanol production (17.441 L t−1). Açaí oil (ca. 30%) was extracted using a Soxhlet apparatus (using hexane as solvent) and detected through gas chromatography coupled to mass spectrometry (GC-MS), where acids accounted for 82.43% of the total composition, while alcohols comprised only 13.15%. For pyrolysis, temperatures (500 and 550 °C), time (20 and 30 min), and activation temperature (750 and 800 °C) were evaluated, resulting in yields of ca. 22% for biochar and 30% for bio-oil. For the bio-oil, the main compounds detected by GC-MS were acids (16.3%), aldehydes (13.08%), amides (12.19%), alcohols (6.72%), and phenols (4.64%). The obtained biochar displayed surface area values of 553.7 m2 g−1 and 10% crystallinity, indicating its more amorphous nature. Amazon Mart açaí, , (açaí) communities dynamics biooil. biooil bio oil. bio-oil reaching 23.5% 235 23 5 secondgeneration second generation 17.441 17441 17 441 (17.44 t−1. t1 t t−1 . 1 t−1) ca (ca solvent GCMS, GCMS GC MS (GC-MS) 8243 82 43 82.43 composition 1315 13 15 13.15% 500 (50 55 °C, C °C 20 (2 3 min, min min) 750 (75 80 evaluated 22 biooil, oil, 16.3%, 163 16.3% 16 (16.3%) 13.08%, 1308 13.08% 08 (13.08%) 12.19%, 1219 12.19% 12 19 (12.19%) 6.72%, 672 6.72% 6 72 (6.72%) 4.64%. 464 4.64% 4 64 (4.64%) 5537 553 7 553. m g1 g g− 10 crystallinity nature (açaí 23.5 2 17.44 1744 44 (17.4 t− (GC-MS 824 8 82.4 131 13.15 50 (5 ( 75 (7 16.3 (16.3% 130 13.08 0 (13.08% 121 12.19 (12.19% 67 6.72 (6.72% 46 4.64 (4.64% 23. 17.4 174 (17. 82. 13.1 16. (16.3 13.0 (13.08 12.1 (12.19 6.7 (6.72 4.6 (4.64 17. (17 13. (16. (13.0 12. (12.1 6. (6.7 4. (4.6 (1 (16 (13. (12. (6. (4. (13 (12 (6 (4

Resumo Sistemas coloidais têm sido usados para encapsular, proteger e liberar óleos essenciais em enxagues bucais. Neste estudo, investigamos o efeito do cloreto de cetilpiridínio (CPC) nas propriedades físico-químicas e na atividade antimicrobiana de sistemas coloidais do tipo óleo-em-água contendo óleo de melaleuca (TTO) e o surfactante não iônico polissorbato 80. Nosso principal objetivo foi avaliar se o CPC poderia melhorar a atividade antimicrobiana do TTO, uma vez que ela é prejudicada quando este óleo essencial é encapsulado com polisorbato 80. Estes sistemas foram preparados com diferentes quantidades de TTO (0-0,5% m/m) e CPC (0-0,5% m/m) para uma concentração final de polissorbato 80 de 2% (m/m). Os resultados de espalhamento de luz dinâmico (DLS) revelaram a formação de micelas e gotículas inchadas de óleo em função da concentração de TTO. Aumentos nas concentrações de CPC resultaram numa redução de cerca de 88% no diâmetro médio das micelas inchadas com óleo. Embora esta variação tenha sido de apenas 20% para as gotículas de óleo, a aparência das amostras mudou de turva para transparente. A carga superficial das estruturas coloidais também foi significativamente afetada pelo CPC, como demonstrado pela transição no potencial zeta de valores levemente negativos para valores muito positivos. Estudos de ressonância paramagnética eletrônica (EPR) mostraram que esta transição é seguida por aumentos significativos na fluidez da monocamada de surfactante em ambas as estruturas coloidais. A atividade antimicrobiana dos sistemas coloidais foi testada contra bactérias Gram-negativas (Escherichia coli) e Gram-positivas (Staphylococcus aureaus). Nossos resultados revelaram que a inibição do crescimento bacteriano é observada para a mesma concentração de CPC (0,05% m/m para E. coli e 0,3% m/m para S. aureus), independentemente do conteúdo de TTO. Estas descobertas sugerem que o TTO não deve atuar como ingrediente ativo em enxagues bucais contendo polissorbato 80. encapsular estudo (CPC físicoquímicas físico químicas óleoemágua água (TTO 00,5% 005 0 0,5% 5 (0-0,5 mm m 8 2 m/m. . (m/m) DLS (DLS 88 20 transparente positivos EPR (EPR Gramnegativas Gram negativas Escherichia Grampositivas positivas Staphylococcus aureaus. aureaus aureaus) 0,05% 05 (0,05 E 03 3 0,3 S aureus, aureus , aureus) 00 00,5 0,5 (0-0, (m/m 0,05 (0,0 0, 00, (0-0 0,0 (0, (0- (0 (

Abstract Colloidal systems have been used to encapsulate, protect and release essential oils in mouthwashes. In this study, we investigated the effect of cetylpyridinium chloride (CPC) on the physicochemical properties and antimicrobial activity of oil-in-water colloidal systems containing tea tree oil (TTO) and the nonionic surfactant polysorbate 80. Our main aim was to evaluate whether CPC could improve the antimicrobial activity of TTO, since this activity is impaired when this essential oil is encapsulated with polysorbate 80. These systems were prepared with different amounts of TTO (0-0.5% w/w) and CPC (0-0.5% w/w), at a final concentration of 2% (w/w) polysorbate 80. Dynamic light scattering (DLS) results revealed the formation of oil-swollen micelles and oil droplets as a function of TTO concentration. Increases in CPC concentrations led to a reduction of around 88% in the mean diameter of oil-swollen micelles. Although this variation was of only 20% for the oil droplets, the samples appearance changed from turbid to transparent. The surface charge of colloidal structures was also markedly affected by the CPC as demonstrated by the transition in zeta potential from slightly negative to highly positive values. Electron paramagnetic resonance (EPR) studies showed that this transition is followed by significant increases in the fluidity of surfactant monolayer of both colloidal structures. The antimicrobial activity of colloidal systems was tested against a Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureaus) bacteria. Our results revealed that the inhibition of bacterial growth is observed for the same CPC concentration (0.05% w/w for E. coli and 0.3% w/w for S. aureus) regardless of TTO content. These findings suggest that TTO may not act as an active ingredient in polysorbate 80 containing mouthwashes. encapsulate mouthwashes study (CPC oilinwater water (TTO 00.5% 005 0 0.5% 5 (0-0.5 ww w w/w, , 2 (w/w DLS (DLS oilswollen swollen 88 20 transparent values EPR (EPR Gramnegative Gram Escherichia Grampositive Staphylococcus aureaus bacteria 0.05% 05 (0.05 E 03 3 0.3 S aureus content 8 00 00.5 0.5 (0-0. 0.05 (0.0 0. 00. (0-0 0.0 (0. (0- (0 (

Resumo Neste estudo o objetivo foi realizar a análise fitoquímica, determinar a toxicidade, e avaliar as atividades antioxidante e antimicrobiana dos extratos da folha da Dipteryx alata Vogel, uma espécie nativa da flora do cerrado brasileiro. Three extracts were prepared using assisted ultrasound and the Soxhlet apparatus, namely, Crude Ultrasound Extract (UCE), Crude Soxhlet Extract (SCE), and the Ethanol Soxhlet Extract (SEE). A análise fitoquímica identificou a presença de flavonoides, taninos, fitoesteróis e saponinas em todos os extratos; alcaloides foram identificados nos extratos SCE e SEE. Na análise using LC-DAD os compostos ácido gálico, rutina, quercetina, luteolina e kampefrol foram determinados em maior concentração no SCE, seguido pelo SEE e UCE, respectivamente. Já a análise by GC-MS revelou a presença de campesterol, estigmasterol e β-sitosterol em todos os extratos, sendo que o UCE e o SCE apresentaram maior concentração de β-sitosterol. O SCE apresentou a maior concentração de todos os compostos identificados. Na análise da atividade antioxidante por DPPH• e ABTS•+, o SEE apresentou maior eficiência (IC50 = 2,98 ± 2,92 e 6,57 ± 0,89 μg/mL, respectivamente). No teste de toxicidade com Allium cepa, todos os extratos estimularam o crescimento radicular na concentração de 50 g/mL; UCE e SEE estimularam o crescimento radicular a 250 g/mL; e o SEE inibiu o crescimento radicular a 750 g/mL. Na análise de toxicidade usando Artemia salina, todos os extratos foram atóxicos. Foi identificada atividade antibacteriana nos microrganismos S. aureus e S. mutans; entretanto, os extratos não apresentaram ação antifúngica contra a cepa de C. albicans. Os extratos da D. alata apresentam potencial terapêutico para aplicabilidade em odontologia. Vogel brasileiro apparatus namely , (UCE) (SCE) . (SEE) flavonoides taninos LCDAD LC DAD gálico rutina quercetina respectivamente GCMS GC MS campesterol βsitosterol β sitosterol βsitosterol. sitosterol. DPPH ABTS ABTS•+ IC50 IC (IC5 298 2 98 2,9 292 92 657 6 57 6,5 089 0 89 0,8 μgmL μg mL μg/mL respectivamente) 5 g/mL gmL g 25 75 salina atóxicos S mutans entretanto C albicans D odontologia (UCE (SCE (SEE ABTS• IC5 (IC 29 9 2, 65 6, 08 8 0, 7

Abstract In this study, our objective was to conduct a comprehensive phytochemical analysis, determine toxicity levels, and assess the antioxidant and antimicrobial properties of extracts derived from the leaves of Dipteryx alata Vogel, a native species of the Brazilian cerrado flora. Three distinct extracts were prepared utilizing assisted ultrasound and the Soxhlet apparatus, namely, Ultrasound Crude Extract (UCE), Soxhlet Crude Extract (SCE), and the Soxhlet Ethanol Extract (SEE). The phytochemical analysis revealed the presence of flavonoids, tannins, phytosterols, and saponins in all extracts. Additionally, alkaloids were specifically identified in the SCE and SEE extracts. In the analysis using LC-DAD, the compounds gallic acid, rutin, quercetin, luteolin and kampefrol were determined in higher concentrations in the SCE, followed by the SEE and UCE, respectively. The GC-MS analysis revealed the presence of campesterol, stigmasterol and β-sitosterol in all extracts, with UCE and SCE showing a higher concentration of β-sitosterol. SCE showed the highest concentration of all identified compounds. In the analysis of antioxidant activity by DPPH• and ABTS•+, SEE showed greater efficiency (IC50 = 2.98 ± 2.92 and 6.57 ± 0.89 μg/mL, respectively). In the toxicity test with Allium cepa, all extracts stimulated root growth at 50 g/mL; UCE and SEE stimulated root growth at 250 g/mL; and SEE inhibited root growth at 750 g/mL. In the Artemia salina toxicity, all extracts were non-toxic. Antibacterial activity was identified in the microorganisms S. aureus and S. mutans; however, the extracts did not show antifungal action against the strain of C. albicans. The extracts of D. alata have therapeutic potential for applicability in dentistry. study levels Vogel flora apparatus namely , (UCE) (SCE) SEE. . (SEE) flavonoids tannins phytosterols Additionally LCDAD, LCDAD LC DAD, DAD LC-DAD acid rutin quercetin respectively GCMS GC MS campesterol βsitosterol β sitosterol βsitosterol. sitosterol. DPPH ABTS ABTS•+ IC50 IC (IC5 298 2 98 2.9 292 92 657 6 57 6.5 089 0 89 0.8 μgmL μg mL μg/mL respectively) cepa 5 g/mL gmL g 25 75 nontoxic. nontoxic non toxic. toxic non-toxic S mutans however C albicans D dentistry (UCE (SCE (SEE ABTS• IC5 (IC 29 9 2. 65 6. 08 8 0. 7

Tetracyclines comprise a large group of broad-spectrum antibiotics used in human and veterinary medicine. Its mechanism of action, via oral ingestion, is to inhibit bacterial protein synthesis, but a large amount (70%) is eliminated without being metabolized, which presents a risk for the arising of antibiotic-resistant species. In this study, the degradation of Tetracycline TC by non-thermal plasma NTP and the antimicrobial sensitivity of the treated solution are investigated. The degradation was followed by chromatographic analysis while the efficiency of NTP in inhibiting the action of TC on bacteria was evaluated by antimicrobial sensitivity test by disk diffusion method. The results showed a high rate of TC degradation, over 90%, in 10 min of NTP treatment for a 60 mL (107 mg L-1) sample and very slow increase up to 94% in 30 min. The antimicrobial sensitivity test of TC after degradation by NTP showed no antibiotic activity. Therefore, our findings are encouraging, since the removal efficiency is below the minimum threshold require, to prevent with high probability, outgrowth of antibiotic-resistant bacteria. In addition, the results confirm that the NTP treated solution is safe to the environment. broadspectrum broad spectrum medicine ingestion synthesis 70% 70 (70% metabolized antibioticresistant resistant species study nonthermal non thermal investigated method 90 90% 1 6 107 (10 L1 L L-1 94 3 activity Therefore encouraging require probability addition environment 7 (70 9 (1 L- (7 (

Resumo O lauril sulfato de sódio é o principal ingrediente de limpeza em xampus, embora possa ser potencialmente prejudicial ao cabelo. A demanda por cosméticos ricos em antioxidantes, por outro lado, tem incentivado as pesquisas com cosméticos verdes. O Brasil possui uma vasta biodiversidade que pode ser explorada para a produção desses cosméticos. O objetivo deste trabalho foi desenvolver uma formulação de xampu antioxidante minimalista sem lauril com extratos de folhas da planta brasileira Hancornia speciosa Gomes. Dois extratos hidroetanólicos foram preparados usando diferentes métodos de extração, Soxhlet e ultrassom. Os extratos foram caracterizados quanto à presença de saponinas, quantificação de polifenóis e identificação química HLPC dos compostos. A atividade antioxidante foi determinada pelo método DPPH. O xampu antioxidante sem lauril foi desenvolvido utilizando hidroxietil celulose com duas concentrações de extrato de folha obtido por Soxhlet, 0.125 mg/g (XP1) e 0.250 mg/g (XP2). Juntamente com a atividade antioxidante, foram avaliadas as propriedades físicas e químicas, potencial de limpeza e qualidade da espuma. O extrato da folha de Soxhlet revelou um perfil químico mais favorável, incluindo resultado positivo para saponinas, além de maior quantidade de polifenóis e aumento da atividade antioxidante. A formulação XP2 apresentou melhor altura de espuma, dispersão de sujeira e atividade antioxidante. Assim, o uso do extrato da folha de mangabeira parece ser promissor para o desenvolvimento de xampus com atividade antioxidante.

Abstract Sodium lauryl sulfate is the main cleaning ingredient in shampoos, even though it may be potentially damaging to hair. The demand for antioxidant-rich cosmetics, on the other hand, has encouraged green cosmetics research. Brazil has vast biodiversity that can be exploited for the production of these cosmetics. This work aimed to develop a minimalist antioxidant lauryl-free shampoo formulation with leaf extracts from the Brazilian plant Hancornia speciosa Gomes. Two hydroethanolic extracts were prepared using different extraction methods, Soxhlet, and ultrasound. The extracts were characterized by the presence of saponins, polyphenol quantification, and HLPC chemical identification of the compounds. Antioxidant activity was determined using the DPPH method. The antioxidant lauryl-free shampoo was developed using hydroxyethyl cellulose with two concentrations of leaf extract obtained by Soxhlet, 0.125 mg/g (XP1) and 0.250 mg/g (XP2). Along with the antioxidant activity, the physical and chemical properties, cleaning potential, and foam quality were evaluated. The Soxhlet leaf extract revealed a more favorable chemical profile, including a positive result for saponins, as well as a larger quantity of polyphenols and increased antioxidant activity. The XP2 formulation showed better foam height, dirt dispersion, and antioxidant activity. Thus, the use of mangabeira leaf extract appears to be promising for the development of shampoos with antioxidant activity.

Cupuaçu husk (CH) is the waste of a common fruit from a native species of the Brazilian Legal Amazon. The current study investigated the influence of ultrasound (US) combined with aqueous, acid, alkaline, and ionic liquid (IL) pretreatments on the chemical and physical aspects of CH and the yield of chemical platforms production, 5-hydroxymethylfurfural (HMF) and furfural (FF), using IL. Scanning electron microscopy, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy were used to feature the raw and pretreated biomass. The highest levels of glucose (9.90 g L-1) were observed in the liquid fraction resulting from the acid + US pretreatment followed by acid hydrolysis. The IL + US pretreatment recorded the best performance in removing lignin. Based on XRD analyses, ultrasound increased crystallinity of all pretreated samples as a result of the removal of cellulose’s amorphous fraction. However, it promoted accessibility to adopted reagents by increasing biomass exposure due to cavitation. The best yields of HMF and FF were recorded from hydrolysis of the solid fraction resulting from the acid + US (12.94%) and alkaline + US (48.84%) pretreatment, respectively. These results indicate satisfactory performance of ultrasound assisted pretreatments to the simplified and economic conversion of biomass into value-added products.

This work uses new waste feedstock, essential to increase the range of new biomasses, demonstrating experimentally and numerically the economic potential of coconut husk residues to produce renewable biofuels (pyrolytic oil and biochar) through slow pyrolysis. The samples were submitted to a pyrolysis process (500 ºC for 30 min, with a heating rate of 20 ºC min-1, using water vapor as carrier gas), where the biochar and bio-oil yields reached were 31 and 30%, respectively. The main components found in bio-oil were furfural (29.23%), phenol (22.18%), and isoeugenol (10.26%). The surface area values (Brunauer-Emmett-Teller (BET) and Langmuir) found for biochar were greater than 300 m2 g-1 and a micropore volume of 0.11 cm3 g-1. The estimated theoretical energy potential of biochar and bio-oil were 208,107,180 MJ and 190,205,438 MJ, equivalent to 3,729,518.4 tons of coconut husks. Thus, this study brings as a novelty a new feedstock associated with bioprocess technological models that will pave sustainable avenues for the development of biorefineries, offering a sustainable green option to produce bioproducts and bioenergy. In the proposed model, the wastes are valorized using various processes addressing economy.

Using molecular simplification and molecular hybridization approaches, a series of 2-(benzylthio)-1H-benzo[d]imidazoles was synthesized and evaluated as in vitro inhibitors of Mycobacterium tuberculosis (M. tuberculosis) growth. Compounds 6p and 6z were considered the lead compounds from this series of molecules, with minimal inhibitory concentration (MIC) values of 6.9 and 3.8 µM against M. tuberculosis H37Rv, respectively. Additionally, the leading compounds were active against multidrug-resistant strains and were devoid of apparent toxicity to Vero and HepG2 cells, from 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red assays. Finally, the compounds presented good aqueous solubility and high plasma stability. These data together indicate that this class of molecules may furnish new anti-tuberculosis drug candidates for future development.

In the current search for renewable energy sources, residual biomass has gained ground in the concept of biorefinery. Furanic compounds such as 5-hydroxymethylfurfural (HMF), furfural (FF) and derivatives such as levulinic acid (LA), obtained from biomass, have emerged as important industrial chemical platforms. In this sense, this work aimed to use pequi bark, typical biomass and abundant in the Brazilian cerrado, in the production of HMF, FF and LA using the ionic liquid 1-n-butyl-3-methyl-imidazole bromide ([BMIM][Br]). The analysis of chemical composition of pequi bark showed that it has potential for use in the production of bioproducts, FF, HMF and LA, with yields of 65, 3 and 23.7%, respectively. High glucose conversion rates were found (> 90%). The analysis of variance (ANOVA) was applied to obtain the mathematical model with α = 0.05, verifying the significance of the second order model established for HMF (F = 0.00167) and FF (0.004494). The model fit is satisfactory, obtaining the coefficient of determination (R2) for the HMF and for the FF of 0.9599 and 0.08422, respectively. From the results obtained, it can be concluded that pequi bark has good precursor capacity for use in biorefinery processes.

Cocos nucifera L. is a palm tree of paramount importance in the food and chemistry industries, although over 50% of its biomass is discarded as waste. The aim of the study is to investigate different pretreatments in to coconut husks (CH), based on acid, alkaline, ionic liquid (IL), and peroxidative, in order to produce fermentable sugars. Severity factors were calculated for pretreatments; values ranged from 0.3 to 1.7 for peroxide, from 0.01 to 1.4 for alkaline, from 1.4 to 2.8 for acid and from 2.0 to 3.0 for ionic liquid. Pretreatments were optimized (time and temperature) to maximize the sugar yield and to remove the total lignin after acid hydrolysis. Reducing sugar yield (70%) was higher when CH waste was alkaline-pretreated for 2 h at 76.21 °C. The highest lignin removal rate was recorded when alkaline (21.4%) and peroxide solutions (27.2%) were used. The IL did not increase sugar yield and was not effective in lignin removal. These outcomes were confirmed through infrared spectroscopy, whereas scanning electron microscopy showed increased biomass porosity during alkaline, acid and peroxide pretreatments. The IL showed little and non-significant changes. The crystallinity index notably increased after each pretreatment; besides, it was directly associated with sugar content.

The aims of the current study are to investigate the composition of biomass from baru processing and to explore the feasibility of valuing it through the development of bioproducts such as fermentable sugars, furanics and biochar. Baru (Dipteryx alata Vog.) waste (endocarp and mesocarp) has great energetic potential to produce bioproducts due to its chemical composition. Proximate analyses applied to such waste have found low favorable moisture and ash content in it. Bioproduct characterizations after acid hydrolysis have shown that baru endocarp and mesocarp biomass can enable a range of value-added products in biorefinery concepts such as furfural and 5-hydroximetylfurfural (20.0 and 1.5% yield, respectively), and high sugar content (approximately 19.15 and 38.40%, respectively). Pyrolysis processes also present high biochar content (ca. 48%), with satisfactory characteristics to be used as fuel, as well as calorific value higher than 30 kJ g-1.

<p>Crystallinity is an important property of lignocellulosic biomass due to its significant effect on acid/enzymatic hydrolysis. Normally, physicochemical analysis, such as powder X-ray diffraction and nuclear magnetic resonance, is used to reveal the crystallinity content. However, these analytical methods are expensive and laborious. In this context, methods that rapidly predict the crystallinity are important, even if used only for screening calibration. Thus, we intend to show the potential of near-infrared spectroscopy (NIRS) and chemometrics to replace reference methods in crystallinity determination. The results show that NIRS can be used to determine crystallinity in banana residues by the use of partial least squares regression, providing good coefficients of determination (R²_cal,pred > 0.82), low relative errors (< 14%) and good range error ratio (≥ 7.7). The interpretation of the regression coefficients, multivariate figures of merit and external validation results indicate a strong relationship between the NIR spectrum and crystallinity in banana samples.</p>

Este trabalho relata a caracterização de compósitos baseados em matriz vitrocerâmica do sistema Li2O-ZrO2-SiO2-Al2O3 (LZSA) reforçados com partículas de ZrSiO4. As propriedades físicas/mecânicas e químicas típicas das bateladas de vidros e dos compósitos foram medidos. Uma composição com 60% em peso de ZrSiO4 foi inicialmente selecionada por ter demonstrado elevados valores de resistência à flexão (190 MPa) e resistência à abrasão profunda (51 mm³). Para esta mesma composição foi adicionado 7% em peso de bentonita a fim de se obter um comportamento de plasticidade adequado para extrusão. As amostras sinterizadas (1150 ºC por 10 min) apresentaram uma retração térmica linear de 14% e valores de resistência à flexão de 220 MPa.

This work reports on the characterization of ZrSiO4 particulate-reinforced Li2O-ZrO2-SiO2-Al2O3 (LZSA) glass-ceramic matrix composites. The typical physical/mechanical and chemical properties of the glass batches and the composites were measured. A composition with 60 wt.% ZrSiO4 was preliminarily selected because it demonstrated the highest values of bending strength (190 MPa) and deep abrasion resistance (51 mm³). To this same composition was given a 7 wt.% bentonite addition in order to obtain plasticity behavior suitable for extrusion. The sintered samples (1150 ºC for 10 min) presented a thermal linear shrinkage of 14% and bending strength values of 220 MPa.

Neste trabalho, filtros com estrutura fibrosa foram produzidos utilizando-se matéria-prima de baixo custo, disponível comercialmente e caracterizados para aplicações em filtração de aerossóis. Mantas refratárias sílico-aluminosas comerciais foram prensadas uniaxialmente, utilizando-se 10% em massa de acetato de polivinila como ligante. Nesta etapa, as amostras foram submetidas à compactação com diferentes pressões para obtenção de diferentes porosidades. Após a prensagem, as amostras foram submetidas a um tratamento térmico a 500 ºC durante 1 h para a degradação do polímero. Subseqüentemente, as amostras foram sinterizadas a 1200 ºC durante 1 h, resultando em uma estrutura fibrilar porosa, composta por mulita (3SiO2.2Al2O3), com porosidade na faixa de 50 a 75%. A morfologia dos filtros fibrosos foi caracterizada através de microscopia eletrônica de varredura, que revelou uma estrutura tridimensional porosa de fibras interconectadas. A resistência mecânica foi avaliada através de ensaios de compressão e de flexão em quatro pontos. Ensaios de permeabilidade e eficiência de coleta de partículas com diferentes diâmetros foram efetuados e os resultados comparados a filtros comerciais. Os valores obtidos para a permeabilidade e eficiência de coleta estão na ordem de grandeza esperada para filtros de gases, apresentando assim grande potencial para aplicações industriais.

Filters with fibrous structure were produced from low cost, commercially available raw materials and characterized for aerosol filtration. Refractory aluminosilicate fibers were uniaxially pressed with polyvinyl acetate as binder. Different pressures were applied, which yielded samples with different porosities. After pressing, the samples were heat treated at 500 ºC during 1 h in air for debinding with subsequent sintering at 1200 ºC for 1 h, which resulted in porous fibrous structures composed mainly by mullite (3SiO2.2Al2O3) with porosity in the range of 50%-75%. The microstructure of the fibrous filters was evaluated by scanning electron microscopy, which revealed a porous morphology comprised by three-dimensional interconnected fibers. Mechanical strength was measured by compressive and 4-point bending tests. Permeability and particle collection efficiency were evaluated and compared with commercially available filters. The permeability and collection efficiency values are in the order of magnitude of cellular supports for aerosol filters and, therefore, suitable for several technological applications.

Espumas vítreas do sistema Li2O-ZrO2-SiO2-Al2O 3 (LZSA) foram produzidas pelo processo gelcasting, associado à aeração de suspensões cerâmicas, sem controle atmosférico. Por meio da adição de diferentes concentrações de agente espumante (Fongraminox) foi possível obter espumas vítreas com densidade relativa variando entre uma estreita faixa (0,10-0,15). As espumas vítreas apresentaram resistência à compressão de 2,5-3,7 MPa, que correspondem a porosidade entre 85 e 89% e macroestrutra com poros aproximadamente esféricos e interconectados. Tais características tornam esses materiais atraentes para as seguintes aplicações tecnológicas: filtros para metais fundidos e gases quentes e, suportes catalíticos.

Vitreous foams in the Li2O-ZrO2-SiO2-Al2O 3 (LZSA) system were produced by the gelcasting process with aeration of ceramic suspensions and without atmospheric control. By the addition of different concentrations of foaming agent (Fongraminox) it was possible to attain glass-ceramic foams in a narrow range of relative density (0.10-0.15). The glass-ceramic foams showed compressive strength of 2.5-3.7 MPa, which corresponds to porosity between 85-89%, and macrostructure with pores nearly spherical and interconnected, these characteristics make these materials attractive for the following applications technology: filters of molten metals and hot gas, and catalytic support.