Desidrogenação do etilbenzeno sobre compostos de ferro e alumínio

Chromium and potassium-doped iron oxides are widely used as industrial catalysts in the dehydrogenation of ethylbenzene to produce styrene. They have several advantages but deactivate with time, because of the loss of potassium. Also, they are toxic due to chromium compounds. Therefore there is a need for developing alternative non toxic catalysts without potassium. Then, iron and aluminum compounds were prepared by different methods in this work. Different phases were produced depending on the preparation method. Aluminum-doped hematite was more active and selective to styrene than the aluminum ferrite. Aluminum acts both as textural and structural promoter in the catalysts.

Gerenciamento de resíduos químicos e águas servidas no laboratório de isótopos estáveis do CENA/USP

A system for disposal and recovery of the main effluents and chemical waist from isotope separation plants and enriched compounds-15N and 34S production has been carried out at the Stable Isotope Laboratory (LIE) of the CENA/USP. Around four hundred thousand liters of effluents has been recovered yearly. Among the recovered chemical wastes, the more relevant are: ammonia; brome; ammonium and sodium sulfate; sodium hydroxide; sulfur dioxide; and hydrochloric acid. Chemical wastes containg recoverable heavy metals (Ag, Cr and Cu) and solvents (methanol, ethanol and acetone) are processed and recovered. Gaseous emissions, mainly H2S are used for recovery of heavy metals solutions. The minimization of the residues waters, as well the reduction of electric energy consume was established using a water deionization system. A cost/effect balance of the process is reported.

Hidrogenação de compostos orgânicos utilizando método eletroquímico para geração de hidrogênio in situ: hidrogenação eletrocatalítica

Electrocatalytic hydrogenation (HEC) may be compared to catalytic hydrogenation (HC). The difference between these methods is the hydrogen source: HC needs a hydrogen gas supply; HEC needs a source of protons (solvent) to be reduced at a cathode surface. HEC has presented interesting advances in the last decades due to investigation of the influence of the supporting electrolyte, co-solvent, surfactant, presence of inert gas and the composition of the electrode on the reaction. Several classes of organic compounds have been hydrogenated through HEC: olefins, ketones, aldehydes, aromatics, polyaromatics and nitro-compounds. This paper shows some details about the HEC which may be regarded as a promising technique for the hydrogenation of organic compounds both in industrial processes and in laboratories.

Constituintes químicos voláteis das flores e folhas do pau-brasil (Caesalpinia echinata, Lam.)

The volatile constituents obtained from a static cryogenic headspace of Caesalpinia echinata Lam. (Leguminosae) showed E-beta-ocimene as the major compound (57.2%), beside other monoterpenes, C6 derivatives like n-hexanal and (E)-2-hexenal and nitrogen compounds such as indole and methyl anthranilate. From the essential oil of the leaves obtained by hydrodistillation in a Clevenger apparatus, (E)-3-hexen-1-ol was identified as the major constituent while phenolic compounds were the most representative class of secondary metabolites.

Tratamento de efluentes industriais por processos oxidativos na presença de ozônio

A large variety of organic and inorganic compounds may be found in wastewater which can contribute to environmental contamination. Oxidation processes with ozone (O3; O3/UV; O3/H2O2; O3/TiO2; O3/Mn+2) and the use of ozone in the pre- or post-treatment of wastewater combined with biological processes has been extensively studied for the treatment of effluents. The aim of this work was to evaluate the potential of the ozonation process in the treatment of several industrial wastewaters, namely effluents from paper mills, and textile, whey (dairy industry), pharmaceutic sand pesticides plants.

Ferro zero: uma nova abordagem para o tratamento de águas contaminadas com compostos orgânicos poluentes

Anthropogenic pollution of groundwater and surface water has become a very serious environmental problem around the world. A wide range of toxic pollutants is recalcitrant to the conventional treatment methods, thus there is much interest in the development of more efficient remediation processes. Degradation of organic pollutants by zero-valent iron is one of the most promising approaches for water treatment, mainly because it is of low cost, easy to obtain and effective. After a general introduction to water pollution and current treatments, this work highlights the advances, applications and future trends of water remediation by zero-valent iron. Special attention is given to degradation of organochloride and nitroaromatic compounds, which are commonly found in textile and paper mill effluents.

Diagnóstico ambiental de metais e organoclorados em córregos adjacentes a áreas de cultivo de cana-de-açúcar (Estado de São Paulo, Brasil)

Sugar cane cultivation in the State of São Paulo has expanded in the last years, with an annual production of 200•10(6) t in an area of 2.5• 10(6) hectares. The use of herbicides, pesticides and fertilizers in sugar cane plantations, together with deforestation of riparian vegetation, have caused impacts on the hydric resources of the adjacent areas. The aim of this work is to evaluate the influence of sugar cane plantations on streams in the central region of the State of São Paulo, studying 16 organochlorinated compounds and 7 metals (Cu, Fe, Cd, Zn, Mn, Cr and Ni) found in the sediments of 11 streams. The results show that there is a higher concentration of metals and organochlorinated compounds in streams without riparian vegetation when compared to forested areas.

Emprego do carvão ativado para remoção de cobre em cachaça

Copper content is of great concern among sugarcane-spirit producers. It is released from copper-made distillers, during the distillation process. Activated carbon has been used to remove copper. However, depending on the amount of carbon and the duration of reaction, it can also remove higher alcohols and esters, which are important in the final product. A sugarcane spirit with 9 mg L-1 of copper was shaken with 2 to 26 g L-1 of activated carbon, during 10 to 1440 minutes. Then, copper and organic compounds were measured. At least 12 g L-1 of carbon and 60 min shaking time were necessary to decrease copper bellow 5 mg L-1. However, other components of the product were also affected.

Potencial antimicrobiano e alelopático das amidas isoladas do extrato das raízes de Ottonia martiana Miq.

Two amides, piperovatine and isopiperlonguminine, were isolated from the roots of Ottonia martiana Miq., a herbaceous shrub commonly used in folk medicine in the treatment of toothache. The crude extract (CE) and isolated compounds were submitted to bioautography and allelopathic assay. The bioautograms allowed the detection of compounds with antibacterial activity and the identification of the bioactive substance piperovatine. The CE and amides exhibited an allelopathic effect on Lactuca sativa (lettuce) seedling growth but did not affect the seeds' germinability.

Efeito do processo de descafeinação com diclorometano sobre a composição química dos cafés arábica e robusta antes e após a torração

The decaffeinated coffee market has been expanding increasingly in the last years. During decaffeination, aroma precursors and bioactive compounds may be extracted. In the present study we evaluate the changes in the chemical composition of C. arabica and C. canephora produced by decaffeination using dichloromethane. A significant change in the chemical composition of both C. arabica and C. canephora species was observed, with differences between species and degrees of roasting. Major changes were observed in sucrose, protein and trigonelline contents after decaffeination. Changes in the levels of total chlorogenic acids and in their isomers distribution were also observed. Lipids and total carbohydrates were not affected as much. The sensory and biological implications of these changes need to be investigated.

Aspectos toxicológicos e químicos da Anatoxina-a e seus análogos

Anatoxin-a and its analogues are azabicyclic alkaloids that represent one of the most powerful nicotinic agonists known for the nicotinic acetylcholine receptor (nAChR). Because of this potent mechanism of action, anatoxin-a and its derivatives represent a target for the discovery of novel drugs. Their syntheses are useful for environmental monitoring and also for pharmacokinetic/pharmacodynamic and toxicological studies. Some strategies for the synthesis of anatoxin-a and analogous compounds are described herein, covering the period from 1996 to the present date. In this review, emphasis is given to the chemical and toxicological aspects of some variants of anatoxin-a, including homoanatoxin-a and anatoxin-a(s).

Avaliação da reação foto-fenton na decomposição de resíduos de carrapaticida

Experimental procedures based on factorial design and surface response methodology were applied to establishe experimental conditions for the decomposition of a 1:400 (v/v) Supocade® (chlorfenvinphos 13.8% and cypermethrin 2.6%) solution, used to control cattle ticks. Experiments exploring photo-oxidative reactions were performed with and without UV radiation, fixing exposition time and pesticide volume, and varying the oxidant mixture. The use of 3.6 mmol L-1 Fe2+ plus 1.9 mol L-1 H2O2 plus UV radiation provided destruction of 94% of the original carbon content and reduction of aromatic, aliphatic and carbinolic compounds, evaluated by determination of residual carbon content by ICP OES and NMR analysis.

Utilização da múltipla voltametria de onda quadrada na determinação eletroanalítica de compostos orgânicos e inorgânicos

This paper reports the development of multiple square wave voltammetry and the possibilities of its use for electroanalytical determinations of organic and inorganic compounds with the improvement of the signal-to-noise ratios and detection limits 2-3 orders of magnitude lower than those obtained with conventional square wave voltammetry. The theoretical aspects and analytical applications were demonstrated as an increased analytical response (current) and application of different pulse modes for different redox processes. Preliminary results obtained for several redox systems using different electrode surfaces are shown, demonstrating also that MSWV represents an excellent alternative for the determination of ultra-traces of organic and inorganic compounds.

Estudo comparativo de técnicas de screening para avaliação da atividade anti-bacteriana de extratos brutos de espécies vegetais e de substâncias puras

In this work, the effectiveness of four screening techniques (three techniques of the diffusion method and one microdilution broth method) were compared. Evaluated were the ethanolic and dichloromethanic extracts of Miconia rubiginosa (Melastomataceae) against six standard bacteria (ATCC). The results showed statistical disagreement among the three diffusion techniques. Among the diffusion techniques, the well technique displayed the best result. However the microdilution broth method demonstrated to be the most adequate method to evaluate the antibacterial activity of plant crude extracts and pure compounds when compared to the other methodologies.

Caracterización y clasificación geoquímica de asfaltitas cubanas

Traditional biomarker parameters and aromatic compounds were applied to characterize and classify ten Cuban asphaltites (asphaltene-rich petroleum occurring as seeps or filling veins, joints, cavities and fissures). Genetic molecular parameters were compared in order to establish oil-oil correlations between samples. Thermal evolution was investigated using saturated biomarker and aromatic maturity parameters. All samples seem to represent petroleum in the early catagenetic stage. Statistical procedures used as auxiliary techniques show that they represent oils of Family II (marine anoxic carbonate sourced oils), except for 2 samples interpreted as belonging to Family III oils (normal marine siliciclastic suboxic sourced oils).