Análise por meio de espectroscopia de emissão óptica das espécies ativas em nitretação iônica e gaiola catódica

Plasma process like ionic nitriding and cathodic cage plasma nitriding are utilized in order to become hard surface of steels. The ionic nitriding is already accepted in the industry while cathodic cage plasma nitriding process is in industrial implementation stage. Those process depend of plasma parameters like electronic and ionic temperature (Te, Ti), species density (ne, ni) and of distribution function of these species. In the present work, the plasma used to those two processes has been observed through Optical Emission Spectroscopy OES technique in order to identify presents species in the treatment ambient and relatively quantify them. So plasma of typical mixtures like N2 H2 has been monitored through in order to study evolution of those species during the process. Moreover, it has been realized a systematic study about leaks, also thought OES, that accomplish the evolution of contaminant species arising because there is flux of atmosphere to inside nitriding chamber and in what conditions the species are sufficiently reduced. Finally, to describe the physic mechanism that acts on both coating techniques ionic nitriding and cathodic cage plasma nitriding

Nitretação iônica sem efeito de borda :desenvolvimento e avaliação de uma nova técnica

The ionic nitriding process presents some limitations related with the control of the thickness of the layer and its uniformity. Those limitations that happen during the process, are produced due to edge effects, damage caused by arcing arc and hollow cathode, mainly in pieces with complex geometry and under pressures in excess of 1 mbar. A new technique, denominated ASPN (active screen shapes nitriding) it has been used as alternative, for offering many advantages with respect to dc plasma conventional. The developed system presents a configuration in that the samples treated are surrounded by a large metal screen at high voltage cathodic potencials, (varying between 0 and 1200V) and currents up to 1 A. The sample is placed in floting potential or polarized at relatively lower bias voltages by an auxiliary source. As the plasma is not formed directly in the sample surface but in the metal screen, the mentioned effects are eliminated. This mechanism allows investigate ion of the transfer of nitrogen to the substrate. Optical and electronic microscopy are used to exam morphology and structure at the layer. X-ray difration for phase identification and microhardness to evaluate the efficiency of this process with respect to dc conventional nitriding

Descarga em barreira dielétrica: construção de um reator DBD e caracterização mediante análises ópticas e elétricas do plasma produzido

The plasma produced by Dielectric Barrier Discharge (DBD) is a promising technique for producing plasma in atmospheric pressure and has been highlighted in several areas, especially in biomedical and textile industry, this is due to the fact that the plasma generated by DBD not reaches high temperatures, enabling use it for thermally sensitive materials. But still it is necessary the development of research related to understanding of the chemical, physical and biological interaction between the non-thermal plasma at atmospheric pressure with cells, tissues, organs and organisms. This work proposes to develop equipment DBD and characterize it in order to obtain a better understanding of the process parameters of plasma production and how it behaves under the parameters adopted in the process, such as distance, frequency and voltage applied between electrodes. For this purpose two techniques were used to characterize distinct from each other. The first was the method of Lissajous figures, this technique is quite effective and accurately for complete electrical characterization equipment DBD. The second technique used was Optical Emission Spectroscopy (EEO) very effective tool for the diagnosis of plasma with it being possible to identify the excited species present in the plasma produced. Finally comparing the data obtained by the two techniques was possible to identify a set of parameters that optimize the production when combined DBD plasma atmosphere in the equipment was built precisely in this condition 0.5mm-15kV 600Hz, giving way for further work

Uso da tecnologia de troca iônica no tratamento de águas contaminadas com Nitrato do Aqüífero Dunas-Barreiras, Natal/RN-Brasil

The city of Natal comprises an area of about 170 km² (65,63 squares miles). The Dunas-Barreiras Aquifer is the most important reservoir of the coastal basin of RN. It is being responsible for the water supplying of about 70% of the population, however, due to the sewage disposal system by cesspools and drains, it is presently affected in a great extent by nitrates contamination. Thus, the present work proposes to research the utilization of contaminated water by nitrates of this fountainhead and find cost of the potable water through the ionic exchange technology. This technology consists in the removal of mineral salts by the exchange of cations for one ion of hydrogen (H+), through the passage of water by cationic resin bed and, secondly, by the exchange of the anions for hydroxyl ions (OH-) through a anionic resin bed. The obtained results have showed the waters derived from fountains, big water holes and shallow wells were microbiologically contaminated, while the waters derived from deep wells (above 70 m 76,58 yards) were free of contamination. Thus, only these ones are suitable to the use of ionic technology. The experiments were conducted with the resin IMAC-HP-555 such as kinetic, thermodynamic, and adsorption by fixed bed studies, being obtained several project variables for the experimental column, as follow: work temperature of 25oC; resin maximum capacity maximum e mean of adsorption ==0,01692 g NO3-1/g R e 0,0110 g NO3-1/g R, respectively. On the experimental column were performed breakthrough tests which pointed for an average ideal average speed of work of 13.2 m / h, with an average efficiency of 45% of adsorption, an optimal concentration of NaCl desorption of 8%, and an ideal desorption time of 80 minutes for the equilibrium conditions of water from the Dunas-Barreiras aquifer. Scale projection for ion-exchange column for denitrification, for these variables, using a computer modeling programme, to project the column of ion exchange ROREX-420/2000, obtained a cost for the drinking water denitrified by this system of R$ 0,16 / m3

Recuperação e purificação de proteínas do soro de queijo tipo coalho usando cromatografia de troca iônica e interação hidrofóbica em leito na forma expandida

Expanded Bed Adsorption plays an important role in the downstream processing mainly for reducing costs as well as steps besides could handling cells homogenates or fermentation broth. In this work Expanded Bed Adsorption was used to recover and purify whey proteins from coalho cheese manufacture using Streamline DEAE and Streamline SP both ionic resins as well as a hydrophobic resin Streamline Phenyl. A column of 2.6 cm inner diameter with 30 cm in height was coupled to a peristaltic pump. Hydrodynamics study was carried out with the three resins using Tris-HCl buffer in concentration of 30, 50 and 70 mM, with pH ranging from 7.0 to 8.0. In this case, assays of the expansion degree as well as Residence Time Distribution (RTD) were carried out. For the recovery and purification steps, a whey sample of 200 mL, was submitted to a column with 25mL of resin previously equilibrated with Tris/HCl (50 mM, pH 7.0) using a expanded bed. After washing, elution was carried out according the technique used. For ionic adsorption elution was carried out using 100 mL of Tris/HCl (50 mM, pH 7.0 in 1M NaCl). For Hydrophobyc interaction elution was carried out using Tris/HCl (50 mM, pH 7.0). Adsorption runs were carried out using the three resins as well as theirs combination. Results showed that for hydrodynamics studies a linear fit was observed for the three resins with a correlation coefficient (R2) about 0.9. In this case, Streamline Phenyl showed highest expansion degree reaching an expansion degree (H0/H) of 2.2. Bed porosity was of 0.7 when both resins Streamline DEAE and Streamline SP were used with StremLine Phenyl showing the highest bed porosity about 0.75. The number of theorical plates were 109, 41.5 and 17.8 and the axial dipersion coefficient (Daxial) were 0.5, 1.4 and 3.7 x 10-6 m2/s, for Streamline DEAE, Streamline SP and Streamline Phenyl, respectively. Whey proteins were adsorved fastly for the three resins with equilibrium reached in 10 minutes. Breakthrough curves showed that most of proteins stays in flowthrough as well as washing steps with 84, 77 and 96%, for Streamline DEAE, Streamline SP and Streamline Phenyl, respectively. It was observed protein peaks during elution for the three resins used. According to these peaks were identified 6 protein bands that could probably be albumin (69 KDa), lactoferrin (76 KDa), lactoperoxidase (89 KDa), β-lactoglobulin (18,3 KDa) e α-lactoalbumin (14 KDa), as well as the dimer of beta-lactoglobulin. The combined system compound for the elution of Streamline DEAE applied to the Streamline SP showed the best purification of whey proteins, mainly of the α-lactoalbumina

Remoção de corantes utilizando tensoativos: extração por ponto de nuvem e floculação iônica

The textile sector is one of the main contributors to the generation of industrial wastewaters due to the use of large volumes of water, which has a high organic load content. In these, it is observed to the presence of dyes, surfactants, starch, alcohols, acetic acid and other constituents, from the various processing steps of the textiles. Hence, the treatment of textile wastewater becomes fundamental before releasing it into water bodies, where they can cause disastrous physical-chemical changes for the environment. Surfactants are substances widely used in separation processes and their use for treating textile wastewaters was evaluated in this research by applying the cloud point extraction and the ionic flocculation. In the cloud point extraction was used as surfactant nonylphenol with 9.5 ethoxylation degree to remove reactive dye. The process evaluation was performed in terms of temperature, surfactant and dye concentrations. The dye removal reached 91%. The ionic flocculation occurs due to the presence of calcium, which reacts with anionic surfactant to form insoluble surfactants capable of attracting the organic matter by adsorption. In this work the ionic flocculation using base soap was applied to the treatment of synthetic wastewater containing dyes belonging to three classes: direct, reactive, and disperse. It was evaluated by the influence of the following parameters: surfactant and electrolyte concentrations, stirring speed, equilibrium time, temperature, and pH. The flocculation of the surfactant was carried out in two ways: forming the floc in the effluent itself and forming the floc before mixing it to the effluent. Removal of reactive and direct dye, when the floc is formed into textile effluent was 97% and 87%, respectively. In the case where the floc is formed prior to adding it to the effluent, the removal to direct and disperse dye reached 92% and 87%, respectively. These results show the efficience of the evaluated processes for dye removal from textile wastewaters.

Estudo de métodos de tratamento de efluentes (troca iônica e eletroquímico) separados e sequenciais para eliminação de derivados de petróleo

The produce of waste and the amount of the water produced coming from activities of petroleum production and extraction has been a biggest challenge for oil companies with respect to environmental compliance due to toxicity. The discard or the reuse this effluent containing organic compounds as BTEX (benzene, toluene, ethylbenzene and xylene) can cause serious environmental and human health problems. Thus, the objective this paper was study the performance of two process (separately and sequential) in one synthetic effluent for the benzene, toluene and xylene removal (volatile hydrocarbons presents in the produced water) through of electrochemical treatment using Ti/Pt electrode and exchange resin ionic used in the adsorption process. The synthetic solution of BTX was prepared with concentration of 22,8 mg L-1, 9,7 mg L-1 e 9,0 mg L-1, respectively, in Na2SO4 0,1 mol L-1. The experiments was developed in batch with 0.3 L of solution at 25ºC. The electrochemical oxidation process was accomplished with a Ti/Pt electrode with different current density (J = 10, 20 e 30 mA.cm-2). In the adsorption process, we used an ionic exchange resin (Purolite MB 478), using different amounts of mass (2,5, 5 and 10 g). To verify the process of technics in the sequential treatment, was fixed the current density at 10 mA cm-2 and the resin weight was 2.5 g. Analysis of UV-VIS spectrophotometry, chemical oxygen demand (COD) and gas chromatography with selective photoionization detector (PID) and flame ionization (FID), confirmed the high efficiency in the removal of organic compounds after treatment. It was found that the electrochemical process (separate and sequential) is more efficient than absorption, reaching values of COD removal exceeding 70%, confirmed by the study of the cyclic voltammetry and polarization curves. While the adsorption (separately), the COD removal did not exceed 25,8%, due to interactions resin. However, the sequential process (electrochemical oxidation and adsorption) proved to be a suitable alternative, efficient and cost-effectiveness for the treatment of effluents petrochemical.

Efeito da força iônica nas propriedades de fluidos de perfuração aquosos à base de polímeros carboxilados e sulfatados

In the well drilling operations problems caused by contamination of the drilling fluid are common. The dissolution of ions from the geological formations affects the rheological and filtration properties of the fluids. These ions shield the charges of ionic polymers, leading to its precipitation. In this work was performed a detailed study on the stability of the properties of aqueous solutions and aqueous drilling fluids in the presence of sulphated and carboxylated polymers, using carboxymethylcellulose and kappa-carrageenan as polymer compounds carboxylated and sulfated model, respectively. The effects of ionic strength of the aqueous medium containing Na+, Mg2+ and Ca2+ on rheological properties of the polymer and drilling fluids solutions were evaluated by varying the concentration of salts, pH and temperature. It was observed that the fluids with κ-carrageenan suffered less influence against the contamination by the ions at pH 9 to 10, even at higher concentrations, but higher influence on pH> 11. The fluids containing carboxymethylcellulose were more sensitive to contamination, with rapid reduction in viscosity and significant increase of the filtrate volume, while the fluid based polymer sulfated kappa-carrageenan showed evidence of interaction with cations and preserve the rheological properties and improved stability the volume of filtrate.

Efeito da força iônica nas propriedades de fluidos de perfuração aquosos à base de polímeros carboxilados e sulfatados

In the well drilling operations problems caused by contamination of the drilling fluid are common. The dissolution of ions from the geological formations affects the rheological and filtration properties of the fluids. These ions shield the charges of ionic polymers, leading to its precipitation. In this work was performed a detailed study on the stability of the properties of aqueous solutions and aqueous drilling fluids in the presence of sulphated and carboxylated polymers, using carboxymethylcellulose and kappa-carrageenan as polymer compounds carboxylated and sulfated model, respectively. The effects of ionic strength of the aqueous medium containing Na+, Mg2+ and Ca2+ on rheological properties of the polymer and drilling fluids solutions were evaluated by varying the concentration of salts, pH and temperature. It was observed that the fluids with κ-carrageenan suffered less influence against the contamination by the ions at pH 9 to 10, even at higher concentrations, but higher influence on pH> 11. The fluids containing carboxymethylcellulose were more sensitive to contamination, with rapid reduction in viscosity and significant increase of the filtrate volume, while the fluid based polymer sulfated kappa-carrageenan showed evidence of interaction with cations and preserve the rheological properties and improved stability the volume of filtrate.

Remoção de fenol de efluentes aquosos utilizando floculação iônica

Oil exploration is one of the most important industrial activities of modern society. Despite its derivatives present numerous applications in industrial processes, there are many undesirable by-products during this process, one of them is water separated from oil, called water production, it is constituted by pollutants difficult to degrade. In addition, the high volume of generated water makes its treatment a major problem for oil industries. Among the major contaminants of such effluents are phenol and its derivatives, substances of difficult natural degradation, which due their toxicity must be removed by a treatment process before its final disposal. In order to facilitate the removal of phenol in wastedwater from oil industry, it was developed an extraction system by ionic flocculation with surfactant. The ionic flocculation relies on the reaction of carboxylate surfactant and calcium íons, yielding in an insoluble surfactant that under stirring, aggregates forming floc capable of attracting the organic matter by adsorption. In this work was used base soap as ionic surfactant in the flocculation process and evaluated phenol removal efficiency in relation to the following parameters: surfactant concentration, phenol, calcium and electrolytes, stirring speed, contact time, temperature and pH. The flocculation of the surfactant occurred in the effluent (initial phenol concentration = 100 ppm) reaching 65% of phenol removal to concentrations of 1300 ppm and calcium of 1000 ppm, respectively, at T = 35 °C, pH = 9.7, stirring rate = 100 rpm and contact time of 5 minutes. The permanence of the flocs in an aqueous medium promotes desorption of the phenol from the flake surface to the solution, reaching 90% of desorption at a time of 150 minutes, and the study of desorption kinetics showed that Lagergren model of pseudo-first order was adequate to describe the phenol desorption. These results shows that the process may configure a new alternative of treatment in regard the removal of phenol of aqueous effluent of oil industry.

Remoção de fenol de efluentes aquosos utilizando floculação iônica

Oil exploration is one of the most important industrial activities of modern society. Despite its derivatives present numerous applications in industrial processes, there are many undesirable by-products during this process, one of them is water separated from oil, called water production, it is constituted by pollutants difficult to degrade. In addition, the high volume of generated water makes its treatment a major problem for oil industries. Among the major contaminants of such effluents are phenol and its derivatives, substances of difficult natural degradation, which due their toxicity must be removed by a treatment process before its final disposal. In order to facilitate the removal of phenol in wastedwater from oil industry, it was developed an extraction system by ionic flocculation with surfactant. The ionic flocculation relies on the reaction of carboxylate surfactant and calcium íons, yielding in an insoluble surfactant that under stirring, aggregates forming floc capable of attracting the organic matter by adsorption. In this work was used base soap as ionic surfactant in the flocculation process and evaluated phenol removal efficiency in relation to the following parameters: surfactant concentration, phenol, calcium and electrolytes, stirring speed, contact time, temperature and pH. The flocculation of the surfactant occurred in the effluent (initial phenol concentration = 100 ppm) reaching 65% of phenol removal to concentrations of 1300 ppm and calcium of 1000 ppm, respectively, at T = 35 °C, pH = 9.7, stirring rate = 100 rpm and contact time of 5 minutes. The permanence of the flocs in an aqueous medium promotes desorption of the phenol from the flake surface to the solution, reaching 90% of desorption at a time of 150 minutes, and the study of desorption kinetics showed that Lagergren model of pseudo-first order was adequate to describe the phenol desorption. These results shows that the process may configure a new alternative of treatment in regard the removal of phenol of aqueous effluent of oil industry.

Análise por meio de espectroscopia de emissão óptica das espécies ativas em nitretação iônica e gaiola catódica

Plasma process like ionic nitriding and cathodic cage plasma nitriding are utilized in order to become hard surface of steels. The ionic nitriding is already accepted in the industry while cathodic cage plasma nitriding process is in industrial implementation stage. Those process depend of plasma parameters like electronic and ionic temperature (Te, Ti), species density (ne, ni) and of distribution function of these species. In the present work, the plasma used to those two processes has been observed through Optical Emission Spectroscopy OES technique in order to identify presents species in the treatment ambient and relatively quantify them. So plasma of typical mixtures like N2 H2 has been monitored through in order to study evolution of those species during the process. Moreover, it has been realized a systematic study about leaks, also thought OES, that accomplish the evolution of contaminant species arising because there is flux of atmosphere to inside nitriding chamber and in what conditions the species are sufficiently reduced. Finally, to describe the physic mechanism that acts on both coating techniques ionic nitriding and cathodic cage plasma nitriding

Nitretação iônica sem efeito de borda :desenvolvimento e avaliação de uma nova técnica

The ionic nitriding process presents some limitations related with the control of the thickness of the layer and its uniformity. Those limitations that happen during the process, are produced due to edge effects, damage caused by arcing arc and hollow cathode, mainly in pieces with complex geometry and under pressures in excess of 1 mbar. A new technique, denominated ASPN (active screen shapes nitriding) it has been used as alternative, for offering many advantages with respect to dc plasma conventional. The developed system presents a configuration in that the samples treated are surrounded by a large metal screen at high voltage cathodic potencials, (varying between 0 and 1200V) and currents up to 1 A. The sample is placed in floting potential or polarized at relatively lower bias voltages by an auxiliary source. As the plasma is not formed directly in the sample surface but in the metal screen, the mentioned effects are eliminated. This mechanism allows investigate ion of the transfer of nitrogen to the substrate. Optical and electronic microscopy are used to exam morphology and structure at the layer. X-ray difration for phase identification and microhardness to evaluate the efficiency of this process with respect to dc conventional nitriding

O bibliotecário e o mercado da documentação popular: CPDCs

CARVALHO, Luciana Moreira. O bibliotecário e a diversidade do mercado da documentação popular: CPDCs. Informação & Sociedade. Estudos, João Pessoa, v. 9, n.2, p. 439-454, 1999.

Nitretação a plasma: fundamentos e aplicações

A nitretação é uma técnica de tratamento de superfície utilizada para endurecer superfícies de metais, principalmente de aços. O uso do plasma para auxiliar esta técnica vem crescendo nos últimos anos. Pelo fato desta técnica utilizar o plasma como fonte energética e este possuir uma vasta aplicação em outras técnicas para processamento de materiais, enobrece ainda mais a leitura do presente livro. Ele apresenta uma revisão da descarga elétrica em gases levando o leitor a refletir, multidisciplinarmente, sobre possibilidades de aplicação da mesma. Apresenta a técnica de nitretação iônica sob o aspecto histórico, científico, tecnológico, operacional e econômico e, finalmente, faz uma revisão das novas técnicas de endurecimento superficial assim como as técnicas convencionais de nitretação