Processos naturais de biodegradação do petróleo em reservatórios

Petroleum biodegradation in reservoirs is a process caused by different microorganisms affecting many oil deposits which modifies the oil composition in a quasi-stepwise process starting from n-alkanes and isoprenoids through to diasteranes. This causes oil souring and increased viscosity, sulfur and metal content, having a direct impact on oil production and refining costs.

Impacto ambiental de kartódromos situados na cidade do Rio de Janeiro: monitoramento de BTEX no ar e do nível de ruído

In this work, noise and aromatic hydrocarbons levels of indoor and outdoor karting circuits located in Rio de Janeiro were assessed. The sampling was perfomed using active charcoal cartridges, followed by solvent desorption and analysis by gas chromatography with mass spectrometry detection. This study demonstrated that the karting circuits, venues for entertainment, were a major source of air pollution with the detection of considerable amounts of these compounds (2.0 to 19.7 µg m-3 of benzene; 4.1 to 41.1 µg m-3 of toluene; 2.8 to 36.2 µg m-3 of ethylbenzene; 0.7 to 36.2 µg m-3 of xylenes) and high noise levels.

Uso da RMN como um sensor online em processos industriais

Nuclear magnetic resonance (NMR) is one of the most versatile analytical techniques for chemical, biochemical and medical applications. Despite this great success, NMR is seldom used as a tool in industrial applications. The first application of NMR in flowing samples was published in 1951. However, only in the last ten years Flow NMR has gained momentum and new and potential applications have been proposed. In this review we present the historical evolution of flow or online NMR spectroscopy and imaging, and current developments for use in the automation of industrial processes.

Oxidação de glicerol sobre nanopartículas de ouro suportadas em carvão ativado: monitoramento quimiométrico da reação por ESI-MS e MIR

A study on the monitoring of glycerol oxidation catalyzed by gold nanoparticles supported on activated carbon under mild conditions by chemometric methods is presented. The reaction was monitored by mass spectrometry-electrospray ionization (ESI-MS) and comparatively by mid infrared spectroscopy (MIR). Concentration profiles of reagent and products were determined by chemometric tools such as Principal Component Analysis (PCA), Evolving Factor Analysis (EFA) and Multivariate Curve Resolution (MCR). The gold nanoparticle catalyst was relatively active in glycerol oxidation, favoring formation of high added value products. It was found that the reaction stabilization was reached at four hours, with approximately 70% glycerol conversion and high selectivity for glycerate.

Influência de processos antagônicos no desenvolvimento de sistema de análises em fluxo para a determinação espectrofotométrica de propiltiouracil em medicamentos

A multi-commuted flow system was developed to determine propylthiouracil (PTU) based on the reaction of its thiol form with iminoquinone radical generated by the oxidation of N,N-dimethyl-p-phenylenediamine in an alkaline medium. PTU can be found in tautomeric forms and the tautomeric equilibrium was displaced to enhance the thiol form. However, the reaction product is unstable and its residence time in the flow path was carefully investigated. The proposed procedure showed good precision (< 1.5%) and a limit of detection (3s) of 0.11 mg L-1. High recoveries were obtained in the validation test. The procedure was employed for propylthiouracil determination in medications.

Óxidos de ferro e suas aplicações em processos catalíticos: uma revisão

A review of most of the reported studies on the use of iron oxides as catalyst in specific processes, namely Haber-Bosch reaction, Fischer-Tropsch synthesis, Fenton oxidation and photolytic molecular splitting of water to produce gaseous hydrogen, was carried out. An essential overview is thus presented, intending to address the fundamental meaning, as well as the corresponding chemical mechanisms, and perspectives on new technological potentialities of natural and synthetic iron oxides, more specifically hematite (α-Fe2O3), goethite (α-FeOOH), magnetite (Fe3O4) and maghemite (γ-Fe2O3), in heterogeneous catalysis.

Atividade de extratos de Arrabidaea chica (Humb. & Bonpl.) Verlot obtidos por processos biotecnológicos sobre a proliferação de fibroblastos e células tumorais humanas

Arrabidaea chica (H&B) Verlot is a plant popularly known as Pariri and this species is a known source of anthocyanins, flavonoids and tannins. This report describes an approach involving enzymatic treatment prior to extraction procedures to enhance A chica crude extract anticancer activity. Anticancer activity in human cancer cell lines in vitro using a 48 h SRB cell viability assay was performed to determine growth inhibition and cytotoxic properties. The final extraction yield without enzyme treatment was higher (24.28%) compared to the enzyme-treated material (19.03%), with an enhanced aglycones anthocyanin ratio as determined by HPLC- DAD and LC-MS with direct infusion.

Avaliação da combinação da nebulização discreta e processos de microextração aplicados à determinação de molibdênio por espectrometria de absorção atômica com chama (FAAS)

Simple and sensitive procedures for the extraction/preconcentration of molybdenum based on vortex-assisted solidified floating organic drop microextraction (VA-SFODME) and cloud point combined with flame absorption atomic spectrometry (FAAS) and discrete nebulization were developed. The influence of the discrete nebulization on the sensitivity of the molybdenum preconcentration processes was studied. An injection volume of 200 µL resulted in a lower relative standard deviation with both preconcentration procedures. Enrichment factors of 31 and 67 and limits of detection of 25 and 5 µg L-1 were obtained for cloud point and VA-SFODME, respectively. The developed procedures were applied to the determination of Mo in mineral water and multivitamin samples.

Remoção do alcatrão de correntes de gaseificação de biomassa: processos e catalisadores

Biomass gasification is a technology that has attracted great interest in synthesis of biofuels and oxo alcohols. However, this gas contains several contaminants, including tar, which need to be removed. Removal of tar is particularly critical because it can lead to operational problems. This review discusses the major pathways to remove tar, with a particular focus on the catalytic steam reforming of tar. Few catalysts have shown promising results; however, long-term studies in the context of real biomass gasification streams are required to realize their potential.

Avaliação da atividade antimicrobiana de soluções de flumequina submetidas aos processos eletroquímico e foto-eletroquímico

Flumequine degradation by electrochemical and photo-electrochemical processes was evaluated in this study. The antimicrobial activity of the solutions subjected to the electrochemical processes was monitored during the assays. The experiments were carried out using DSA® (dimensionally stable anode) electrode. The influence of current density was investigated for the 7.5 to 45 mA cm-2 range. The photo-electrochemical process was more efficient for degrading flumequine (85%) and reducing solution antimicrobial activity. For both processes, the residual antimicrobial activity decreased as flumequine degradation increased. The reaction intermediate m/z 244 (5-methyl-1-oxo-6,7-dihydro-1H,5H-pyrido[3,2,1-ij]quinoline-2-carboxylic acid) was identified.

Ocorrência e degradação de quinolonas por processos oxidativos avançados

In this review, the presence of quinolones in the environment, their risks and the available processes for water decontamination were addressed. Their occurrence in surface waters and also in soil raises concerns about the risk of the development of resistant bacteria and other potential chronic effects. AOPs (UV/H2O2, Fenton, photo-Fenton, and UV/TiO2) and ozonation proved effective for degrading these emerging contaminants due to hydroxyl radical formation, surpassing the efficacy of conventional methods. In addition, the main degradation mechanisms of these drugs as well as data on residual biological activity were analyzed.

MONITORAMENTO DE RESÍDUOS DE AGROTÓXICOS DA CLASSE DOS ORGANOFOSFORADOS POR CGDFC EM AMOSTRAS DE LEITE FLUÍDO E EM PÓ

Samples of whole fluid pasteurized, UHT and powdered milk were analyzed for the presence of organophosphorus pesticide residues (OPR) using the QuEChERS method with detection by GC-FPD and confirmation by UPLC-MS/MS. A total of 23% of fluid milk samples and 27% of powdered milk samples contained at least one organophosphorus residue. The OPR found in the samples showed these can reach the milk and remain even after pasteurization, sterilization and drying processes. Some domestic sanitary residues were also present in the powdered milk samples. These residues have no LMR in Brazilian food legislation and are therefore not taken into account in food intake evaluations. There was an unidentified chromatographic peak in 30% of all the liquid and powdered milk samples, indicating the presence of some other contaminant.

PREPARAÇÃO E CARACTERIZAÇÃO DE MEMBRANAS DE CELULOSE REGENERADA A PARTIR DA CELULOSE EXTRAÍDA DE RESÍDUOS AGROINDUSTRIAIS PARA APLICAÇÃO EM PROCESSOS DE SEPARAÇÃO

The aim of this study was to produce membranes using the adapted cuprammonium method. The cellulose utilized was obtained from recycled agroindustrial residues: sugarcane bagasse, corn stover and soybean hulls. The levels of Cu (II) ions in regenerated cellulose membranes produced with cellulose from bagasse, corn stover and soybean hulls were 0.0236 wt%, 0.0255 wt% and 0.0268 wt%, respectively. These levels were approximately 15 times lower than those observed in previous studies (0.3634 wt%). Cellular viability data show that membranes produced from bagasse cellulose do not present toxicity to the cellular cultures studied. These results demonstrate an evolution in production of regenerated cellulose membranes from agroindustrial residues mainly due to a decrease in the Cu (II) ions level, showing the possibility of application of these systems with improved membranes processing.

KIT COLORIMÉTRICO PARA DETECÇÃO DE METANOL EM ETANOL COMBUSTÍVEL PARA O MONITORAMENTO DA QUALIDADE DE COMBUSTÍVEIS

A colorimetric kit for methanol detection in ethanol-containing fuels and ease of use in the field was developed and tested. The analysis can detect the presence of methanol in fuels when exceeding specification (0.5% v/v) in about 20 min and its simple instrumentation does not require a specialist. The kit method was successfully validated at gas stations located in São Paulo State and the Federal District.

CONSIDERAÇÕES TÉCNICAS QUANTO AO USO DA VOLTAMETRIA DE VARREDURA ESCALONADA EM PROCESSOS ADSORTIVOS

Cyclic voltammetry has become one of the most useful tools in modern electrochemistry, but the use of digital potentiostats should be treated with caution by users. Staircase Voltammetry utilizes some parameters to build up the potential ramp. However, for some electrochemical processes, the signal response can be different compared with that acquired using true linear sweep (analogic signal). In this work, the role of SCV parameters in current response during the hydrogen electrochemical adsorption/desorption reaction on a platinum surface was studied. In addition, the transient current in each step comprising the ramp was investigated. The results showed that with a step height of 2 mV, the SCV response matches that recorded by linear sweep voltammetry. From the transient current study, two kinds of capacity were identified: non-faradaic and faradaic charge.