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The regional montmorillonite clay from Santo Amaro da Purification, the region of Reconcavo Baiano, was subjected to chemical treatment for the destruction of organic matter, after which the pillarization technique was applied using the hydroxyacetatoferro precursor (III) in order to generate a isomerization of butane 1. The solids were characterized by conventional techniques such as: DRX, TG/DTA, specific surface area measurement, MEV and RTP, in order to evaluate their importance as a clay-resercible that can be restructured chemical composition and crystallographic.. The results indicated that the pillarization resulted in the formation of thermally stable iron oxide. The Bronsted acid sites, detected by absorbed pyridine FTIR, were active in the geometric isomerization of butenes, with 22% selectivity to the cis isomer and 47% to the trans isomer.

The dependence of oil and its consequent commercial fluctuation make researchers to seek viable alternatives for their gradual replacement. The present work aims to evaluate the production of biofuels from the slow pyrolysis of the Syzygium malaccense biomass (Malay Apple) through thermogravimetric analysis (TGA-DTG), Fraser-Suzuki deconvolution and chemometric tools of multivariate analysis. Three chemical treatments (sodium hydroxide, sulfuric acid and phosphoric acid) were evaluated, as well as the variation in the heating rate and the consequent effects on the pyrolysis of biomass for the production of biofuels, totaling 16 pyrolysis routes (including the use of biomass no treatment). In the obtained data, multivariate analysis tools were used, looking for groups that presented favorable characteristics for the production of quality biofuels. Heatmap, k-means and SOM analysis indicated the routes that use phosphoric acid treatment and heating rates of 10 or 15 °C/min (Jap10 and Jap15, respectively) as relevant, because they have low lignin contents and high gaseous cellulose and hemicellulose contents.

Lucina pectinata, popularly called Lambreta, is a delicacy very consumed in Bahian cuisine. The shell is composed of nacreous layers formed by keratin, collagen, and elastin, interspersed with layers of calcium carbonate, predominantly calcite, and aragonite phases, which provides protection to the mollusk. As these shells do not readily degrade, provoking environmental imbalance due to their accumulation, this work aims to evaluate the physicochemical and microstructural properties of shells of the species L. pectinata, focusing on the reuse of the solid residue generated by the consumption of this mollusk. The shells were washed, crushed, and subjected to chemical treatment and dried. Subsequently, the physical–chemical and microstructural properties of the samples LN—in nature and LB were treated with sodium hypochlorite. The samples were investigated using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), zero load potential (pHpcz), pH determination, moisture content (%), ash content (%), specific surface area, and pore volume by the BET method, scanning electron microscopy (MEV), thermogravimetric/derivate thermogravimetry (TG/DTG), and differential thermal analysis (DTA). The results revealed that calcite and argonite phases are present in the two samples with high calcium carbonate content (95%) and that thermal decomposition occurs in the range of 575 to 810 °C, producing CaO and CO2. Treatment with sodium hypochlorite (sample LB) promoted leaching in the solid by dragging possible lamellae, which culminated in superficial erosion of solids, resulting in a better cavity and pore distribution profile on the surface, besides increasing the specific surface area in relation to sample LN.

O discente, ao estudar o conteudo geometria molecular, muitas das vezes nao consegue visualizar estas estruturas no espaco tridimensional dificultando assim o seu entendimento no processo de aprendizagem. Visando diminuir essa lacuna,esse artigo apresenta a construcao e emprego de modelos molecularesdo tipo bola e ima como uma ferramenta para facilitar a visualizacao, por parte do aluno, bem como desenvolver a sua habilidade de utilizar modelos para visualizacao de moleculas.Na construcao dos modelos, os alunospassaram a ser agentes ativosdo processo de aprendizagem do conhecimento, construiram representacoes, assim como, reconheceram que foi uma boa estrategia didatica para tornar a aula mais dinâmica.

A discussão mundial e adoção de práticas relacionadas à sustentabilidade, culminaram no reaproveitamento de resíduos provenientes da agroindústria em concordância com os 3R's empregados no país. Segundo dados atuais do IBGE, o Brasil em 2020, produziu 690 mil toneladas de maracujá amarelo (M) - (Passiflora edullis f. flavicarpa), sendo o maior produtor mundial. Contudo cerca de 70% deste percentual é de casca e semente, que se descartados de forma inadequada pode causar impactos ao meio ambiente. A casca deste fruto, é composta por celulose, hemicelulose, lignina e pectina, que se conectam por meio de pontes de cálcio intermoleculares, sendo capazes de estabelecer interações com espécies externas à sua estrutura, tornando-a promissora para o reaproveitamento. Neste sentido, este estudo visou reaproveitar as conchas da Lambreta(L) - Lucina pectinata como fonte de carbonato de cálcio empregando-a no enriquecimento da casca do maracujá amarelo fazendo uso da técnica squeeze-flow. As investigações foram realizadas a partir da variação da proporcionalidade entre as duas biomassas, gerando novos materiais que foram denominados ML11, ML12, ML13, LM12 e LM13. Os efeitos da mistura das biomassas, foram evidenciados através das técnicas de caracterização: FTIR, TG/DTG, DSC e MEV. Os eventos de degradação térmica das amostras foram avaliados através dos parâmetros cinéticos e termodinâmicos pelo método de Kissinger. Os resultados obtidos constataram um aumento na estabilidade térmica dos constituintes das fibras do maracujá amarelo pelo enriquecimento com carbonato de cálcio oriundo da Lucina pectinata nas amostras ML11, ML12. Pode-se notar que a baixa energia de ativação nas amostras LM12 e ML13 conduz à diminuição da estabilidade térmica desses materiais indicando uma condição ideal na proporcionalidade entre as duas biomassas envolvidas, favorecendo a aplicação desses materiais em processos termoquímicos. Por meio das observações realizadas nos experimentos de FTIR foi possível observar a supressão da banda relacionada ao estiramento -CO (1605 cm-1) indicando a eficiência da técnica squeeze-flow na estrutura do maracujá corroborando com as micrografias obtidas.

In the present work, two chemometric strategies were evaluated to assess the influence of the chemical pretreatment: a Kohonen self-organizing map neural network and a Support Vector Machine Learning algorithm. Kohonen ANN was able to predict the influence of chemical treatment mainly on pseudo-component lignin, since cellulose and hemicellulose have similar structures; presenting a topological error of 0.044 and a quantification error of 0.193, while the Vector Supporting Machine (SVM) algorithm was able to predict the classes with accuracy of 0.956, area under the ROC curve (AUC) of 0.992 and F1 score of 0.956, proving to be a more effective strategy in predicting the influence of the chemical treatment on the rambutan shells based on the kinetic parameters. It was also observed an increase in the activation energy for the cellulose pretreated with sodium hydroxide and with phosphoric acid, mainly due to the partial conversion of type I cellulose into type II cellulose, ranging from 152 to 155 kJ/mol versus 124 kJ/mol for the untreated sample. The thermal decomposition mechanism did not change significantly, being estimated as pseudo-zero order, using the Master-Plot method. TG-FTIR analysis reveals that the main gases emitted during pyrolysis are CO2, H2O and CO, being the carbon dioxide-related band an indicator of the influence of the chemical treatment. This analysis also reveals the release of sulfur compounds from the sample treated with sulfuric acid, indicating that the environmental point of view of this sample shows no viability as use as pyrolysis feedstock.

The present paper reports the advantages, drawbacks and applications of the main techniques of sample preparation employed during the determinations of total mercury and methylmercury in food matrices employing analytical methods such as: cold vapor atomic absorption spectrometry (CV AAS), cold vapor atomic fluorescence spectrometry (CV AFS), inductively coupled plasma mass spectrometry (ICP-MS), voltammetry, and neutron activation analysis. The use of slurry sampling, solid sampling, microwave assisted extraction, reflux system by cold finger and Vigreux column was discussed. Also a brief text on the use of chromatographic techniques for the speciation analysis of mercury is presented. A list of 134 references is cited and the analytical characteristics of some these procedures proposed are shown as tables.

In the present work is described a new on-line solid-phase extraction system using a novel ion imprinted polymer as adsorbent for the preconcentration and determination of mercury(II) in natural water samples by Cold Vapor Atomic Fluorescence Spectrometry (CV AFS). The ion imprinted polymer was prepared by the improved bulk polymerization technique, occurring in only 3 h, based on mercury(II)-dithizone chelate, using methacrylic acid as monomer, ethylene glycol dimethacrylate as cross-linking reagent, 2,2′‑azobisisobutyronitrile as radical initiator, and dimethyl sulfoxide and acetonitrile as porogen solvents. The obtained polymer was characterized by Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermogravimetry (TG), Derivative Thermogravimetry (DTG) and X-ray Diffraction (XRD). The on-line system was mounted by the easy coupling the mini-column packed with the Hg2+-IIP sorbent to the cold vapor system of the spectrometer. The optimum experimental conditions for the on-line preconcentration system were established employing multivariate methodology (two-level full factorial design and Doehlert matrix). Under the optimized conditions, limits of detection and quantification of 0.02 and 0.06 μg L−1, and preconcentration factor of 29 were obtained for the determination of mercury using the developed on-line system, considering a sample volume of 50 mL. Precision expressed as a relative standard deviation (RSD%) was of 5.2% (n = 7) for a standard solution with mercury(II) concentration of 0.5 μg L−1. Then, the on-line system was applied for the selective preconcentration and determination of mercury (II) in four natural water samples, and addition/recovery tests were performed to evaluate the accuracy of the method. All analyzed samples presented Hg2+ concentrations below the limit of quantification of the proposed method and the recovery values found were in range from 90 to 105%.

In this paper, a new way for γ-Alumina synthesis was proposed, the raw material being aluminum powders obtained by high-energy milling of aluminum cans. This seems a good option for this metal recycling and energy saving, as well as hydrogen production. The materials were prepared by precipitation techniques, in which aluminum powders reacted with hydrochloric acid, giving aluminum chloride, which was subsequently transformed into aluminum hydroxide by reaction with ammonium hydroxide or sodium hydroxide as precipitant agents, and finally into γ-Alumina by calcination. Results showed that the used preparation methods gave a γ-Alumina structure, confirmed by XRD, with surface areas values (174 and 204 m2 g-1) close to those of a commercial γ-Alumina Cyanamid Ketjen (180 m2 g-1) or an alumina prepared by a typical precipitation route (203 m2 g-1). Using sodium hydroxide as precipitant agent turned out to be more ecologically compatible since it did not release harmful environmental compounds. Fil: Adans, Ysla França. Instituto Federal Da Bahia; Brasil Fil: Martins, André Rosa. Instituto Federal Da Bahia; Brasil Fil: Coelho, Rodrigo Estevam. Instituto Federal Da Bahia; Brasil Fil: Das Virgens, Cesário Francisco. Universidade Do Estado Da Bahia; Brasil Fil: Ballarini, Adriana Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera". Universidad Nacional del Litoral. Instituto de Investigaciones en Catálisis y Petroquímica "Ing. José Miguel Parera"; Argentina Fil: Carvalho, Luciene Santos. Instituto Federal Da Bahia; Brasil

Mercury is a highly toxic substance that is a health hazard to humans. This study aims to investigate powders obtained from the peel of the fruit of Pachira aquatica Aubl, in its in natura and/or acidified form, as an adsorbent for the removal of mercury ions in aqueous solution. The materials were characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. The infrared spectra showed bands corresponding to the axial deformation of carbonyls from carboxylic acids, the most important functional group responsible for fixing the metal species to the adsorbent material. The thermograms displayed mass losses related to the decomposition of three major components, i.e., hemicellulose, cellulose, and lignin. The adsorption process was evaluated using cold-vapor atomic fluorescence spectrometry (CV AFS) and cold-vapor atomic absorption spectrometry (CV AAS). Three isotherm models were employed. The adsorption isotherm model, Langmuir-Freundlich, best represented the adsorption process, and the maximum adsorption capacity was predicted to be 0.71 and 0.58 mg g(-1) at 25 °C in nature and acidified, respectively. Adsorption efficiencies were further tested on real aqueous wastewater samples, and removal of Hg(II) was recorded as 69.6 % for biomass acidified and 76.3 % for biomass in nature. Results obtained from sorption experiments on real aqueous wastewater samples revealed that recovery of the target metal ions was very satisfactory. The pseudo-second-order model showed the best correlation to the experimental data. The current findings showed that the investigated materials are potential adsorbents for mercury(II) ion removal in aqueous solution, with acidified P. aquatica Aubl being the most efficient adsorbent.

A cloud point extraction procedure for pre-concentration and determination of cadmium and lead in drinking water using sequential multi-element flame atomic absorption spectrometry is described. 4-(2-thiazolylazo)-orcinol (TAO) has been used as complexing agent and the micellar phase was obtained using the non-ionic surfactant octylphenoxypolyethoxyethanol (Triton X-114) and centrifugation. The conditions for reaction and extraction (surfactant concentration, reagent concentration, effect of incubation time, etc) were studied and the analytical characteristics of the method were determined. The method allows the determination of cadmium and lead with quantification limits of 0.30 µg L−1 and 2.6 µg L−1, respectively. A precision expressed as relative standard deviation (RSD, n = 10) of 2.3% and 2.6% has been obtained for cadmium concentrations of 10 µg L−1 and 30 µg L−1, respectively, and RSD of 1.3% and 1.7% for lead concentrations of 10 µg L−1 and 30 µg L−1, respectively. The accuracy was confirmed by an...

The present work proposes the use of Agave sisalana (sisal fiber) as an natural adsorbent for ions Pb(II) and Cd(II) biosorption from natural waters. The flame atomic absorption spectrometry was used for quantitative determination and study of the ions Pb(II) and Cd(II) adsorption on the solid phase. The Fourier transform infrared spectroscopy (FT IR) was used to investigate the sisal structure and the specific BET surface area was analyzed. The biosorption potential of sisal as biosorbent for the removal of the ions Pb(II) and Cd(II) from aqueous solution was investigate considering the followings parameters: pH, biomass amount and contact time. Langmuir and Freundlich isotherms were used to evaluate adsorption behavior of the ions on this solid phase. The results showed that sisal has a surface area to adsorption of 0.0233 m2 g− 1, and the OH and CO functional groups are the main involved in the biosorption. The best interpretation for the experimental data was given by Freundlich isotherm that proposes a monolayer sorption with a heterogeneous energetic distribution of active sites, accompanied by interactions between sorbed molecules. The maximum monolayer biosorption capacity was found to be 1.85 mg g− 1 for Cd (II) and 1.34 mg g− 1 for Pb (II) at pH 7 and 296 K. This phase solid can be used for biosorption of cadmium and lead in polluted natural waters.

The specific surface area of zirconia, prepared by an aqueous sol-gel route, is affected by aging and by the rinsing solution of the precipitate. The solid aged in mother liquor and rinsed with ammonium hydroxide solution showed the highest value.