Espectrometria de massas com ionização por "electrospray": processos químicos envolvidos na formação de íons de substâncias orgânicas de baixo peso molecular

An overview of the current literature on the chemical processes involved in the ion formation from low molecular weight organic compounds by electrospray ionization mass spectrometry is given.

Síntese e emprego do ciclometalado [Pd(dmba)(N3)(PPh3)] em processos catalíticos envolvendo a n-carbonilação redutiva de nitroarenos a carbamatos e na síntese de derivados da uréia

This work deals with the use of the cyclometallated compound [Pd(dmba)(N3)(PPh3)] in homogeneous catalytic processes comprising the reductive N-carbonylation of nitrobenzene and p-nitrotoluene to ethyl-phenylcarbamate and ethyl-4-methylphenylcarbamate, respectively. The cyclopalladated compound was also employed in the synthesis of urea derivatives by reacting p-nitrotoluene and m-nitrotoluene, respectively, with p-toluidine and and m-chloroaniline.

Química Analítica de Processos

Process Analytical Chemistry (PAC) is an important and growing area in analytical chemistry, that has received little attention in academic centers devoted to the gathering of knowledge and to optimization of chemical processes. PAC is an area devoted to optimization and knowledge acquisition of chemical processes, to reducing costs and wastes and to making an important contribution to sustainable development. The main aim of this review is to present to the Brazilian community the development and state of the art of PAC, discussing concepts, analytical techniques currently employed in the industry and some applications.

Estresse oxidativo, lesões no genoma e processos de sinalização no controle do ciclo celular

The generation of reactive oxygen species (ROS) may be both beneficial to cells, performing functions in intracellular signaling and detrimental, modifying cellular biomolecules. ROS can cause DNA damage, such as base damage and strand breaks. Organisms respond to chromosome insults by activation of a complex and hierarchical DNA-damage response pathway. The extent of DNA damages determines cell fate: cell cycle arrest and DNA repair or cell death. The ATM is a central protein in the response to DNA double-strand breaks by acting as a transducer protein. Collected evidences suggest that ATM is also involved in the response to oxidative DNA damage.

Fundamentos e aplicações ambientais dos processos fenton e foto-fenton

Wastewater and soil treatment processes based on Fenton's reagent have gained great attention in recent years due to its high oxidation power. This review describes the fundaments of the Fenton and photo-Fenton processes and discusses the main aspects related to the degradation of organic contaminants in water such as the complexation of iron, the use of solar light as the source of irradiation and the most important reactor types used. An overview of the main applications of the process to a variety of industrial wastewater and soil remediations is presented.

Reator de membrana enzimático e fluidos supercríticos: associação de processos

The aim of this work is to present the new applications of membrane technology in fat and oil processing, with emphasis on development and applications of the enzymatic membrane reactor and its association with extraction and purification technology by supercritical fluids (SCF). Combining the extraction by SCFs and the separation by membranes allows the integration of extractions reactions with selective separation by membranes through filtration of the supercritical mixture (SCF + extracted solutes). This association provides important energy savings regarding the SCF recompression costs.

Geoquímica de fósforo como indicadora da qualidade ambiental e dos processos estuarinos do Rio Jaguaribe - costa nordeste oriental brasileira

Phosphorus geochemistry as a proxy of environmental estuarine processes at the Jaguaribe River, Northeastern Brazil. Sedimentation of different phosphorus geochemical fractions can characterize the natural or anthropogenic processes dominant in the watershed. Selective chemical extraction of different phosphorus geochemical forms in estuarine sediments showed the predominance of inorganic over organic forms suggesting an increase in inorganic phosphorus input from anthropogenic sources. Local hydrochemistry favors the dominance of inorganic ferric and carbonatic phosphorus. Ongoing changes in the estuarine throphy, from mesothrophic to euthrophic, may decrease the immobilization of these forms, increasing dissolved phosphorus and favoring euthrophy. Detritic phosphorus suggests a fluvial origin of this fraction and acts as a tracer of river influence upon the estuary.

Degradação do pesticida Padron® por processos fotoquímicos utilizando luz artificial e solar

Destruction of Padron® (dye and picloram) was evaluated using a photoreactor and a solar reactor. Photolysis was observed using only a germicide lamp (GL). Black light (BL) and H2O2 (172 mmol L-1) promoted a conversion of 49% and 6% of dye and picloram, respectively. Photocatalytic processes were more efficient using TiO2/GL (96%-dye; 60%-picloram) than TiO2/BL (44%-dye; 40%-picloram). Photolysis using sunlight was not observed during PadronÒ recirculation in the reactor constructed with four borosilicate tubes. Meanwhile, adding H2O2 resulted in 12% conversion of dissolved organic compounds. Finally, the most efficient mineralization (60%) was obtained using the Fenton reaction ( H2O2-176 mmol L-1; FeSO4x6H2O-90 mmol L-1) and sunlight.

Avaliação do potencial de processos oxidativos avançados para remediação de águas contaminadas com geosmina e 2-MIB

In this work, the efficiency of some homogeneous advanced oxidation processes (UVC/H2O2, Fe2+/H2O2, UVC/Fe2+/H2O2, UVA/Fe2+/H2O2, solar/Fe2+/H2O2) was investigated toward the degradation of geosmin and 2-methylisoborneol (2-MIB). The effect of relevant experimental parameters (ie. pH, Fe2+ and H2O2 concentration) was first investigated by factorial design, using camphor as a model substrate. In the geosmin and 2-MIB degradation studies the Fenton processes assisted by solar and UVA radiation offered the most promising results, mainly on account of high degradation capacity (higher than 80% at a reaction time of 60 min), high operational simplicity and low cost.

Processos avançados de oxidação de compostos fenólicos em efluentes industriais

In an effort to minimize the impact on the environment, removal of pollutants, such as phenolic compounds, from the industrial wastewater has great importance nowadays because of the high toxicity and low biodegradability of these compounds. This work discusses the different methods to remove these compounds from industrial wastewater, showing their advantages and disadvantages. Advanced Oxidation Process (AOPs) are presented as a promising technology for the treatment of wastewater containing phenolic compounds. Among the AOPs, photolysis, photocatalysis and the processes based on hydrogen peroxide and on ozone are discussed with emphasis on the combined processes and the oxidation mechanisms.

Aplicação da química quântica computacional no estudo de processos químicos envolvidos em espectrometria de massas

The field of application of mass spectrometry (MS) has increased considerably due to the development of ionization techniques. Other factors that have stimulated the use of MS are the tandem mass spectrometry (MS/MS) and sequential mass spectrometry (MSn) techniques. However, the interpretation of the MS/MS and MSn data may lead to speculative conclusions. Thus, various quantum chemical methods have been applied for obtaining high quality thermochemical data in gas phase. In this review, we show some applications of computational quantum chemistry to understand the formation and fragmentation of gaseous ions of organic compounds in a MS analysis.

Imobilização de ferro (II) em matriz de alginato e sua utilização na degradação de corantes têxteis por processos Fenton

In this work Fenton and photo-Fenton processes for textile dye degradation were investigated using iron (II) immobilized in alginate spheres. Photomicrographs obtained by scanning electron microscopy showed an irregular and porous surface with a homogeneous distribution of iron. The Fenton process was used to evaluate the degradation efficiency of reactive dyes and this procedure showed a low degradation effect. The association of artificial visible light or solar radiation in the Fenton process (foto-Fenton process) showed degradation ratios of 70 and 80% respectively in 45 min. It was also observed that the iron-alginate matrix can be reused.

Glutationa e enzimas relacionadas: papel biológico e importância em processos patológicos

Glutathione (GSH) and related enzymes are pivotal for the normal functioning of several important biological processes. In this review we discuss the biosynthesis and the catalytic cycles of glutathione as well as the major GSH-related enzymes. We also present how glutathione and enzymes are involved in cancer and the chromatographic and non-chromatographic methods used to analyze glutathione and/or its derivatives.

Degradação de corantes ácidos por processos oxidativos avançados usando um reator com disco rotatório de baixa velocidade

Three technologies were tested (TiO2/UV, H2O2/UV, and TiO2/H2O2/UV) for the degradation and color removal of a 25 mg L-1 mixture of three acid dyes: Blue 9, Red 18, and Yellow 23. A low speed rotating disc reactor (20 rpm) and a H2O2 concentration of 2.5 mmol L-1 were used. The dyes did not significantly undergo photolysis, although they were all degraded by the studied advanced oxidation processes. With the TiO2/H2O2/UV process, a strong synergism was observed (color removal reached 100%). Pseudo first order kinetic constants were estimated for all processes, as well as the respective apparent photonic efficiencies.

Processos físico-químicos em drenagem ácida de mina em mineração de carvão no sul do Brasil

Acid mine drainage generated from coal mine showed a pH of 3.2, high concentrations of SO4(2-), Al, Fe, Mn, Zn and minor As, Cd, Co, Cr, Cu, Ni and Pb. The major reduction in the concentration occurred for Al, As, Cr, Fe and Pb after the treatment with CaO. The evolution of these acid waters within the tributary stream showed decreasing concentration for all soluble constituents, except Al. This natural attenuation was controlled by pH (6.4 to 10.8) as a result of concurrent mixing with tributary stream and reaction with local bedrock that contains limestone. Aluminum increasing concentration during this evolution seems to be related to an input of Al-enriched waters due to the leaching of silicate minerals in alkaline conditions.