Osvaldo Chiavone-filho - Academia.edu (original) (raw)

Papers by Osvaldo Chiavone-filho

Fluid Phase Equilibria, 2021

Abstract Monoethylene glycol (MEG) is used as hydrate inhibitor in natural gas exploitation. Duri... more Abstract Monoethylene glycol (MEG) is used as hydrate inhibitor in natural gas exploitation. During the process, MEG mixed with produced water and salts must be regenerated. Therefore, salt solubility and physicochemical properties of MEG aqueous mixture with electrolytes are useful to operate the regeneration unit. This work determines density and electrical conductivity data at 298.15 K for water+MEG+CaCl2 systems. The density data were correlated applying the excess volume approach and Redlich Kister expansion, resulting absolute and relative mean deviations of 3 × 10–4 g‧cm–3 and 0.028%. For electrical conductivity correlation a semiempirical model was applied resulting absolute and relative mean deviations of 1.27 mS‧cm–1 and 3.53%. CaCl2 solubilities in water-MEG mixtures at 298.15 and 323.15 K were also measured. The proposed analytical method used precise density measurements to determine salt solubility. Moreover, the solid phase composition was determined by thermogravimetry analysis. Four different solid phases were identified as function of the solvent composition. At 298.15 K the addition of MEG changed the solid phase from CaCl2•4H2O to CaCl2•3H2O•MEG for w’MEG ≥0.36. Regarding 323.15 K, solid phase changed from CaCl2•2H2O to CaCl2•H2O•MEG for w’MEG≥0.30. Density, electrical conductivities and CaCl2 solubilities were accurately determined and are of interest to the natural gas industry.

Fluid Phase Equilibria, 2016

From experimental studies in literature, it has been proven that the phase behavior of supercriti... more From experimental studies in literature, it has been proven that the phase behavior of supercritical carbon dioxide with pure or mixed solvents or solutes may not be simple, and in many cases, a second liquid phase appears. In this work, we considered the phase behavior of supercritical carbon dioxide with two essential oils, namely, eucalyptus oil and rosemary oil. We investigated the phase behavior of each system of CO 2 + eucalyptus oil and CO 2 + rosemary oil separately, and we observed that both systems form a second liquid phase. We measured the bubble point pressures of both systems for five different concentrations of CO 2 , and also the three phase line of liquid-liquid-vapor of these systems. Based on the observed upper solution critical points, we concluded that the phase behavior of these two systems is Type-III based on the Scott and Van Konynenburg phase classification.

Anais do Congresso Brasileiro de Engenharia Química em Iniciação Científica - Cobeq IC 2015, 2015

Anais do Congresso Brasileiro de Engenharia Química em Iniciação Científica - Cobeq IC 2015, 2015

O ácido 2,4-diclorofenoxiacético (2,4-D) é um herbicida sintético extensivamente usado no Brasil,... more O ácido 2,4-diclorofenoxiacético (2,4-D) é um herbicida sintético extensivamente usado no Brasil, e devido a sua baixa solubilidade em água, é comum encontrá-lo adsorvido ao solo. O 2,4-D e seus precursores, fenol e 2,4-diclorofenol (2,4-DCF), são considerados poluentes de difícil degradação, devido a sua alta toxicidade (limites aceitáveis em solo de 100 a 500 mg/kg de solo seco), e encontram-se entre os poluentes com prioridade de estudo pelos principais órgãos ambientais internacionais. Os métodos convencionais de remediação de solos não são efetivos para altas concentrações destes compostos em solos. Além disso, solos arenosos apresentam, em geral, alta permeabilidade, que permite o fluxo destes contaminantes até as águas subterrâneas, passando a contaminar estas águas. A remediação de solo arenoso, em escala piloto, contaminado com 2,4-D, 2,4-DCF e fenol foi realizada usando sulfato ferroso e peróxido de hidrogênio (reação Fenton). Os resultados mostram a efetividade do uso da ...

Journal of Environmental Management, 2015

The present work investigates the conjugation of flotation and photo-Fenton techniques on oil rem... more The present work investigates the conjugation of flotation and photo-Fenton techniques on oil removal performance from oilfield produced water. The experiments were conducted in a column flotation and annular lamp reactor for induced air flotation and photodegradation steps, respectively. A nonionic surfactant was used as a flotation agent. The flotation experimental data were analyzed in terms of a first-order kinetic rate model. Two experimental designs were employed to evaluate the oil removal efficiency: fractional experimental design and central composite rotational design (CCRD). Overall oil removal of 99% was reached in the optimum experimental condition after 10 min of flotation followed by 45 min of photo-Fenton. The results of the conjugation of induced air flotation and photo-Fenton processes allowed meeting the wastewater limits established by the legislations for disposal.

Desalination and Water Treatment, 2014

AbstractOil separation from produced water is commonly carried out at oilfields for resource reco... more AbstractOil separation from produced water is commonly carried out at oilfields for resource recovery as well as environmental reasons. In this work, the separation of oil by induced air flotation was studied in a batch unit. A series of nonionic surfactants with different hydrophile–lipophile balance (HLB) values were used as a flotation agent. The effects of different HLB values and surfactant concentration on the oil removal of oilfield produced water were investigated. The removal rate constant (k) was determined and the flotation process followed first-order kinetics. The maximum oil removal obtained was approx. 80% after 4 min of flotation.

Water, Air, & Soil Pollution, 2013

Effluents of resin production, petrochemicals, refineries, paper mills, and iron foundry industri... more Effluents of resin production, petrochemicals, refineries, paper mills, and iron foundry industries may present high concentrations of phenol. The high toxicity, solubility, and stability of phenolic compounds hamper the treatment of this wastewater by conventional methods. In this work, the effect of inorganic ion mixtures, such as chloride, nitrate, sulfate, carbonate, and monophosphate on the phenol mineralization by the photo-Fenton process, was investigated. The kinetic of phenol mineralization was monitored with the analysis of total organic carbon. Two experimental designs were employed to evaluate the influence of inorganic ions on mineralization efficiency: fractional experimental design and central composite rotatable design (CCRD). The pollutant degradation reached 100 % at 60 min in the absence of salts, but in a saline medium, this value was reduced to 10 %. The sequence of the inhibitory effect was H 2 PO 4 − ≫ Cl − > SO 4 2− > NO 3 − ≈ CO 3 2. The statistical data analysis showed that the phosphate and chloride ion concentrations were studied variables and statistically significant on the mineralization process. The analysis of variance showed: (1) good fit between the observed and prediction values for fractional experiment design and CCRD and (2) according to Fisher distribution, the models that were obtained were considered significant and predictive.

Water Science and Technology, 2013

CuO/ZnO coupled oxide films were electrodeposited onto an aluminum substrate and tested as photoc... more CuO/ZnO coupled oxide films were electrodeposited onto an aluminum substrate and tested as photocatalysts in degradation of phenol molecules in aqueous solution under sunlight. The obtained films were characterized by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the photocatalytic activity of films was significant, especially to coupled oxide film with a CuO/ZnO ratio equal to 0.697, which presented about 70% degradation of the aromatic molecules and 42% of total organic carbon (TOC) removal at 300 min under solar irradiation. Therefore, this work highlights the potential application of CuO/ZnO coupled oxide films obtained by electrodeposition onto aluminum substrate in the field of photocatalysis.

Thermochimica Acta, 1999

The purpose of the present work is to study the solid±liquid equilibrium in aqueous multi-electro... more The purpose of the present work is to study the solid±liquid equilibrium in aqueous multi-electrolyte systems using the quasiisothermic thermometric technique (QTT). The principle of the QTT is based on thermal effects associated with the phase transformations that occur in the system. In order to test the apparatus, salt solubility data at 298.15 K for the aqueous systems H 2 ONaClKCl, H 2 ONaClNa 2 SO 4 , H 2 ONiCl 2 NiSO 4 are presented. The data obtained for the three systems are in good agreement with the literature, including solid phase boundaries due to hydration. This agreement indicates the accuracy of the proposed method. Furthermore, the system with nickel salts are now experimentally determined.

The Journal of Chemical Thermodynamics, 2013

In this work, activity coefficients at infinite dilution (c 1 13) have been measured for 21 solut... more In this work, activity coefficients at infinite dilution (c 1 13) have been measured for 21 solutes (subscript 1) (alkanes, cycloalkanes, alkenes, aromatic compounds, alcohols, esters, ketones, and halogenated hydrocarbons), in four solvents (subscript 3), namely one saturated fatty acid and three unsaturated fatty acids: stearic (octadecanoic) acid-C18:0, oleic (cis-9-octadecenoic) acid-C18:1 9c, linoleic (cis,cis-9,12octadecadienoic) acid-C18:2 9c12c, and linolenic (cis,cis,cis-9,12,15-octadecatrienoic) acid-C18:3 9c12c15c, by gas-liquid chromatography. The measurements were carried out at temperatures from (303.13 to 368.19) K and the partial molar excess Gibbs free energy (DG E;1 1), enthalpy (DH E;1 1), and entropy (DS E;1 1), at infinite dilution were calculated from experimental c 1 13 values obtained over the temperature range. The uncertainties in determination of c 1 13 and DH E;1 1 are 4% and 20%, respectively. The results for stearic acid obtained in this study have been compared to those available in the Dortmund Data Bank (DDB). The real behaviour of fatty systems could be better understood through the results obtained in this work.

The Journal of Supercritical Fluids, 2014

Polychlorinated Biphenyls (PCBs) are chlorinated organic substances which are highly toxic and ar... more Polychlorinated Biphenyls (PCBs) are chlorinated organic substances which are highly toxic and are also considered persistent organic pollutants (POPs). It should be emphasized the environmental importance for treating wastes with PCBs. For instance, Stockholm Convention on POPs established the elimination of the use of PCBs in equipments, e.g. electrical transformers and capacitors, by 2025. The decontamination of materials containing PCBs may be performed by supercritical extraction technology using carbon dioxide (CO 2) as solvent. The first objective of this work was the formulation of a computational tool to correlate solubility data of aromatic compounds in supercritical CO 2 , using Peng-Robinson equation of state with fitted parameters. In a second step, a description of askarel oil, like araclor 1254, solubility in supercritical CO 2 was provided for simulation purposes of the extraction process. PCB mixture has predominance of congeners: penta, hexa, heptachloro biphenyl, tri and tetrachlorobenzene. The calculation procedure was initially used for a series of aromatic compounds (naphthalene, biphenyl, anthracene and phenanthrene) in order to test the approach. Experimental solubility data collection has been elaborated from the literature, providing a systematic series of binary and ternary data of the aromatic compounds with CO 2. The binary parameters for the mixing rule were systematically estimated, together with a new set of Clausius-Clapeyron solute vapor pressure to better describe the temperature dependence and achieve experimental uncertainties. Finally, the estimated parameters were used to simulate solubility values of the Askarel oil as function of the operational conditions of extraction by a simultaneous solution of the equilibrium equations for each compound. The thermodynamic modeling demonstrated to be feasible for process analysis and design.

Journal of Hazardous Materials, 2012

Produced water in oil fields is one of the main sources of wastewater generated in the industry. ... more Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min −1 for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H 2 O 2 concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal.

Journal of Food Engineering, 2005

Croton zehntneri Pax et Hoff is indigenous to the Northeastern of Brazil; is rich in (E)-anethole... more Croton zehntneri Pax et Hoff is indigenous to the Northeastern of Brazil; is rich in (E)-anethole and is largely used in cooking to impart flavor to a variety of foods; is used in folk medicine to treat indigestion, insomnia, etc. In this work the volatile oil from C. zehntneri was extracted using pressurized CO 2. Both kinetic and solubility experiments were performed at pressures of 66.7 and 78.5 bar and temperatures from 10 to 28°C. The composition of the volatile oil was determined using gas chromatography. The maximum solubility (2.83 • 10 À2 kg/kg) was observed at 15°and 66.7 bar while the maximum global yield (3.4%, mass) was detected at 20°C at the same pressure. The volatile oil was formed predominantly by (E)-anethole (73.6%, area), alpha-muurolene (7.51%), methyl chavicol or estragole (2.52%), germacrene D (2.11%) and small amounts of other terpenoidic compounds. The overall extraction curves were fitted by several models from the literature. The models that best described the overall extraction curves were the Goto et al., Martínez et al., and Sovová.

Journal of Chemical & Engineering Data, 1993

A simple and accurate apparatus for the measurement of salt solubilities in mixed solvents by an ... more A simple and accurate apparatus for the measurement of salt solubilities in mixed solvents by an analytical method is presented. Salt solubility data have been measured at 298.15,323.15, and 348.15 K for the following ternary systems: water + ethanol + KCl, water + 1,2-ethanediol+ KCl, water + 2-methoxyethanol+ KC1, water + 2-ethoxyethanol+ KCl, water + l-methoxy-2-propanol+ KC1, water + 2-isopropoxyethanol+ KCl, water + 2-methoxyethanol + KBr, and water + 2-butoxyethanol + KBr. The solubility of the salt was observed to decrease with rising temperature for solvent mixtures with a high concentration of glycol ether and to increase with temperature for low glycol ether contents. Liquid-liquid equilibria of some of the salt-saturated solutions have also been determined.

Journal of Chemical & Engineering Data, 1993

A Dvoiak-Boubllk recirculating still has been used to measure isothermal vaporliquid equilibrium ... more A Dvoiak-Boubllk recirculating still has been used to measure isothermal vaporliquid equilibrium data for 1,2-ethanediol + water and for five different glycol ether + water systems. The glycol ethers are 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, 2-ieopropoxyethanol, and 2-butoxyethanol. Each system has been measured at two temperatures in the range 343.15-368.15 K. The reliability of the data has been checked by using a maximum likelihood data reduction.

Fluid Phase Equilibria, 2007

High-pressure density data for cyclohexane + n-hexadecane mixtures at a wide temperature range wa... more High-pressure density data for cyclohexane + n-hexadecane mixtures at a wide temperature range was modeled with several classical equations of state (EOS) and correlative models. A modification for softening the co-volume and another for a volume scaling of the Peng-Robinson EOS (VS-PR) were proposed. The VS-PR model is able to correlate the pure component experimental data employing only five adjustable parameters, with root-mean-square deviation (RMSD) between calculated and experimental densities essentially within the experimental error. This result is superior to widely used approaches, i.e., a six parameter Tait model and six parameter volume translations (temperature and pressure dependent) for Peng-Robinson and Patel-Teja EOS. The VS-PR model also represents well the isobaric thermal expansion and the isothermal compressibility coefficients of the pure cyclohexane, a small naphthenic substance as well as a long chain n-alkane hydrocarbon, n-hexadecane. When modeling the mixture data, the use of VS-PR model of pure components along with the Redlich-Kister expansion, truncated at the first term, the density was correlated within a RMSD only 60% greater than the experimental error. The proposed model is able to accurately represent all the tested mixture data with a relatively small number of parameters.

Environmental Technology, 2014

Environmental Science & Technology, 2004

The photo-Fenton process utilizes ferrous ions (Fe 2+), hydrogen peroxide (H 2 O 2), and ultravio... more The photo-Fenton process utilizes ferrous ions (Fe 2+), hydrogen peroxide (H 2 O 2), and ultraviolet (UV) irradiation as a source of hydroxyl radicals for the oxidation of organic matter present in aqueous effluents. The cost associated with the use of artificial irradiation sources has hindered industrial application of this process. In this work, the applicability of solar radiation for the photodegradation of raw gasoline in water has been studied. The photo-Fenton process was also applied to a real effluent, i.e., oilfield-produced water, and the experimental results demonstrate the feasibility of employing solar irradiation to degrade this complex saturated-hydrocarbon-containing system.

Ceramics International, 2014

Ternary zinc spinel oxides such as Zn 2 SnO 4 , ZnAl 2 O 4 and ZnFe 2 O 4 were synthesized and ch... more Ternary zinc spinel oxides such as Zn 2 SnO 4 , ZnAl 2 O 4 and ZnFe 2 O 4 were synthesized and characterized, and their activities in the photodegradation of phenol molecules were investigated. Zn 2 SnO 4 , ZnAl 2 O 4 and ZnFe 2 O 4 powders were synthesized by hydrothermal, metalchitosan complexation and solvothermal routes, respectively. The face-centered cubic spinel structure of each material was confirmed by powder X-ray diffractometry (XRD) and its porous structure by N 2 adsorption-desorption isotherms. The characterization of spinels was complemented with Fourier transform infrared spectroscopy (FTIR) and X-rays fluorescence (XRF), revealing the formation of spinel structures with high purity. The photocatalytic activity in the degradation of phenol was observed only with Zn 2 SnO 4 oxide. Mineralization degree of phenol molecules by Zn 2 SnO 4 photocatalyst determined by total organic carbon analysis (TOC) reached 80% at 360 min under sunlight.

Fluid Phase Equilibria, 2021

Abstract Monoethylene glycol (MEG) is used as hydrate inhibitor in natural gas exploitation. Duri... more Abstract Monoethylene glycol (MEG) is used as hydrate inhibitor in natural gas exploitation. During the process, MEG mixed with produced water and salts must be regenerated. Therefore, salt solubility and physicochemical properties of MEG aqueous mixture with electrolytes are useful to operate the regeneration unit. This work determines density and electrical conductivity data at 298.15 K for water+MEG+CaCl2 systems. The density data were correlated applying the excess volume approach and Redlich Kister expansion, resulting absolute and relative mean deviations of 3 × 10–4 g‧cm–3 and 0.028%. For electrical conductivity correlation a semiempirical model was applied resulting absolute and relative mean deviations of 1.27 mS‧cm–1 and 3.53%. CaCl2 solubilities in water-MEG mixtures at 298.15 and 323.15 K were also measured. The proposed analytical method used precise density measurements to determine salt solubility. Moreover, the solid phase composition was determined by thermogravimetry analysis. Four different solid phases were identified as function of the solvent composition. At 298.15 K the addition of MEG changed the solid phase from CaCl2•4H2O to CaCl2•3H2O•MEG for w’MEG ≥0.36. Regarding 323.15 K, solid phase changed from CaCl2•2H2O to CaCl2•H2O•MEG for w’MEG≥0.30. Density, electrical conductivities and CaCl2 solubilities were accurately determined and are of interest to the natural gas industry.

Fluid Phase Equilibria, 2016

From experimental studies in literature, it has been proven that the phase behavior of supercriti... more From experimental studies in literature, it has been proven that the phase behavior of supercritical carbon dioxide with pure or mixed solvents or solutes may not be simple, and in many cases, a second liquid phase appears. In this work, we considered the phase behavior of supercritical carbon dioxide with two essential oils, namely, eucalyptus oil and rosemary oil. We investigated the phase behavior of each system of CO 2 + eucalyptus oil and CO 2 + rosemary oil separately, and we observed that both systems form a second liquid phase. We measured the bubble point pressures of both systems for five different concentrations of CO 2 , and also the three phase line of liquid-liquid-vapor of these systems. Based on the observed upper solution critical points, we concluded that the phase behavior of these two systems is Type-III based on the Scott and Van Konynenburg phase classification.

Anais do Congresso Brasileiro de Engenharia Química em Iniciação Científica - Cobeq IC 2015, 2015

Anais do Congresso Brasileiro de Engenharia Química em Iniciação Científica - Cobeq IC 2015, 2015

O ácido 2,4-diclorofenoxiacético (2,4-D) é um herbicida sintético extensivamente usado no Brasil,... more O ácido 2,4-diclorofenoxiacético (2,4-D) é um herbicida sintético extensivamente usado no Brasil, e devido a sua baixa solubilidade em água, é comum encontrá-lo adsorvido ao solo. O 2,4-D e seus precursores, fenol e 2,4-diclorofenol (2,4-DCF), são considerados poluentes de difícil degradação, devido a sua alta toxicidade (limites aceitáveis em solo de 100 a 500 mg/kg de solo seco), e encontram-se entre os poluentes com prioridade de estudo pelos principais órgãos ambientais internacionais. Os métodos convencionais de remediação de solos não são efetivos para altas concentrações destes compostos em solos. Além disso, solos arenosos apresentam, em geral, alta permeabilidade, que permite o fluxo destes contaminantes até as águas subterrâneas, passando a contaminar estas águas. A remediação de solo arenoso, em escala piloto, contaminado com 2,4-D, 2,4-DCF e fenol foi realizada usando sulfato ferroso e peróxido de hidrogênio (reação Fenton). Os resultados mostram a efetividade do uso da ...

Journal of Environmental Management, 2015

The present work investigates the conjugation of flotation and photo-Fenton techniques on oil rem... more The present work investigates the conjugation of flotation and photo-Fenton techniques on oil removal performance from oilfield produced water. The experiments were conducted in a column flotation and annular lamp reactor for induced air flotation and photodegradation steps, respectively. A nonionic surfactant was used as a flotation agent. The flotation experimental data were analyzed in terms of a first-order kinetic rate model. Two experimental designs were employed to evaluate the oil removal efficiency: fractional experimental design and central composite rotational design (CCRD). Overall oil removal of 99% was reached in the optimum experimental condition after 10 min of flotation followed by 45 min of photo-Fenton. The results of the conjugation of induced air flotation and photo-Fenton processes allowed meeting the wastewater limits established by the legislations for disposal.

Desalination and Water Treatment, 2014

AbstractOil separation from produced water is commonly carried out at oilfields for resource reco... more AbstractOil separation from produced water is commonly carried out at oilfields for resource recovery as well as environmental reasons. In this work, the separation of oil by induced air flotation was studied in a batch unit. A series of nonionic surfactants with different hydrophile–lipophile balance (HLB) values were used as a flotation agent. The effects of different HLB values and surfactant concentration on the oil removal of oilfield produced water were investigated. The removal rate constant (k) was determined and the flotation process followed first-order kinetics. The maximum oil removal obtained was approx. 80% after 4 min of flotation.

Water, Air, & Soil Pollution, 2013

Effluents of resin production, petrochemicals, refineries, paper mills, and iron foundry industri... more Effluents of resin production, petrochemicals, refineries, paper mills, and iron foundry industries may present high concentrations of phenol. The high toxicity, solubility, and stability of phenolic compounds hamper the treatment of this wastewater by conventional methods. In this work, the effect of inorganic ion mixtures, such as chloride, nitrate, sulfate, carbonate, and monophosphate on the phenol mineralization by the photo-Fenton process, was investigated. The kinetic of phenol mineralization was monitored with the analysis of total organic carbon. Two experimental designs were employed to evaluate the influence of inorganic ions on mineralization efficiency: fractional experimental design and central composite rotatable design (CCRD). The pollutant degradation reached 100 % at 60 min in the absence of salts, but in a saline medium, this value was reduced to 10 %. The sequence of the inhibitory effect was H 2 PO 4 − ≫ Cl − > SO 4 2− > NO 3 − ≈ CO 3 2. The statistical data analysis showed that the phosphate and chloride ion concentrations were studied variables and statistically significant on the mineralization process. The analysis of variance showed: (1) good fit between the observed and prediction values for fractional experiment design and CCRD and (2) according to Fisher distribution, the models that were obtained were considered significant and predictive.

Water Science and Technology, 2013

CuO/ZnO coupled oxide films were electrodeposited onto an aluminum substrate and tested as photoc... more CuO/ZnO coupled oxide films were electrodeposited onto an aluminum substrate and tested as photocatalysts in degradation of phenol molecules in aqueous solution under sunlight. The obtained films were characterized by X-ray diffraction, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results showed that the photocatalytic activity of films was significant, especially to coupled oxide film with a CuO/ZnO ratio equal to 0.697, which presented about 70% degradation of the aromatic molecules and 42% of total organic carbon (TOC) removal at 300 min under solar irradiation. Therefore, this work highlights the potential application of CuO/ZnO coupled oxide films obtained by electrodeposition onto aluminum substrate in the field of photocatalysis.

Thermochimica Acta, 1999

The purpose of the present work is to study the solid±liquid equilibrium in aqueous multi-electro... more The purpose of the present work is to study the solid±liquid equilibrium in aqueous multi-electrolyte systems using the quasiisothermic thermometric technique (QTT). The principle of the QTT is based on thermal effects associated with the phase transformations that occur in the system. In order to test the apparatus, salt solubility data at 298.15 K for the aqueous systems H 2 ONaClKCl, H 2 ONaClNa 2 SO 4 , H 2 ONiCl 2 NiSO 4 are presented. The data obtained for the three systems are in good agreement with the literature, including solid phase boundaries due to hydration. This agreement indicates the accuracy of the proposed method. Furthermore, the system with nickel salts are now experimentally determined.

The Journal of Chemical Thermodynamics, 2013

In this work, activity coefficients at infinite dilution (c 1 13) have been measured for 21 solut... more In this work, activity coefficients at infinite dilution (c 1 13) have been measured for 21 solutes (subscript 1) (alkanes, cycloalkanes, alkenes, aromatic compounds, alcohols, esters, ketones, and halogenated hydrocarbons), in four solvents (subscript 3), namely one saturated fatty acid and three unsaturated fatty acids: stearic (octadecanoic) acid-C18:0, oleic (cis-9-octadecenoic) acid-C18:1 9c, linoleic (cis,cis-9,12octadecadienoic) acid-C18:2 9c12c, and linolenic (cis,cis,cis-9,12,15-octadecatrienoic) acid-C18:3 9c12c15c, by gas-liquid chromatography. The measurements were carried out at temperatures from (303.13 to 368.19) K and the partial molar excess Gibbs free energy (DG E;1 1), enthalpy (DH E;1 1), and entropy (DS E;1 1), at infinite dilution were calculated from experimental c 1 13 values obtained over the temperature range. The uncertainties in determination of c 1 13 and DH E;1 1 are 4% and 20%, respectively. The results for stearic acid obtained in this study have been compared to those available in the Dortmund Data Bank (DDB). The real behaviour of fatty systems could be better understood through the results obtained in this work.

The Journal of Supercritical Fluids, 2014

Polychlorinated Biphenyls (PCBs) are chlorinated organic substances which are highly toxic and ar... more Polychlorinated Biphenyls (PCBs) are chlorinated organic substances which are highly toxic and are also considered persistent organic pollutants (POPs). It should be emphasized the environmental importance for treating wastes with PCBs. For instance, Stockholm Convention on POPs established the elimination of the use of PCBs in equipments, e.g. electrical transformers and capacitors, by 2025. The decontamination of materials containing PCBs may be performed by supercritical extraction technology using carbon dioxide (CO 2) as solvent. The first objective of this work was the formulation of a computational tool to correlate solubility data of aromatic compounds in supercritical CO 2 , using Peng-Robinson equation of state with fitted parameters. In a second step, a description of askarel oil, like araclor 1254, solubility in supercritical CO 2 was provided for simulation purposes of the extraction process. PCB mixture has predominance of congeners: penta, hexa, heptachloro biphenyl, tri and tetrachlorobenzene. The calculation procedure was initially used for a series of aromatic compounds (naphthalene, biphenyl, anthracene and phenanthrene) in order to test the approach. Experimental solubility data collection has been elaborated from the literature, providing a systematic series of binary and ternary data of the aromatic compounds with CO 2. The binary parameters for the mixing rule were systematically estimated, together with a new set of Clausius-Clapeyron solute vapor pressure to better describe the temperature dependence and achieve experimental uncertainties. Finally, the estimated parameters were used to simulate solubility values of the Askarel oil as function of the operational conditions of extraction by a simultaneous solution of the equilibrium equations for each compound. The thermodynamic modeling demonstrated to be feasible for process analysis and design.

Journal of Hazardous Materials, 2012

Produced water in oil fields is one of the main sources of wastewater generated in the industry. ... more Produced water in oil fields is one of the main sources of wastewater generated in the industry. It contains several organic compounds, such as benzene, toluene, ethyl benzene and xylene (BTEX), whose disposal is regulated by law. The aim of this study is to investigate a treatment of produced water integrating two processes, i.e., induced air flotation (IAF) and photo-Fenton. The experiments were conducted in a column flotation and annular lamp reactor for flotation and photodegradation steps, respectively. The first order kinetic constant of IAF for the wastewater studied was determined to be 0.1765 min −1 for the surfactant EO 7. Degradation efficiencies of organic loading were assessed using factorial planning. Statistical data analysis shows that H 2 O 2 concentration is a determining factor in process efficiency. Degradations above 90% were reached in all cases after 90 min of reaction, attaining 100% mineralization in the optimized concentrations of Fenton reagents. Process integration was adequate with 100% organic load removal in 20 min. The results of the integration of the IAF with the photo-Fenton allowed to meet the effluent limits established by Brazilian legislation for disposal.

Journal of Food Engineering, 2005

Croton zehntneri Pax et Hoff is indigenous to the Northeastern of Brazil; is rich in (E)-anethole... more Croton zehntneri Pax et Hoff is indigenous to the Northeastern of Brazil; is rich in (E)-anethole and is largely used in cooking to impart flavor to a variety of foods; is used in folk medicine to treat indigestion, insomnia, etc. In this work the volatile oil from C. zehntneri was extracted using pressurized CO 2. Both kinetic and solubility experiments were performed at pressures of 66.7 and 78.5 bar and temperatures from 10 to 28°C. The composition of the volatile oil was determined using gas chromatography. The maximum solubility (2.83 • 10 À2 kg/kg) was observed at 15°and 66.7 bar while the maximum global yield (3.4%, mass) was detected at 20°C at the same pressure. The volatile oil was formed predominantly by (E)-anethole (73.6%, area), alpha-muurolene (7.51%), methyl chavicol or estragole (2.52%), germacrene D (2.11%) and small amounts of other terpenoidic compounds. The overall extraction curves were fitted by several models from the literature. The models that best described the overall extraction curves were the Goto et al., Martínez et al., and Sovová.

Journal of Chemical & Engineering Data, 1993

A simple and accurate apparatus for the measurement of salt solubilities in mixed solvents by an ... more A simple and accurate apparatus for the measurement of salt solubilities in mixed solvents by an analytical method is presented. Salt solubility data have been measured at 298.15,323.15, and 348.15 K for the following ternary systems: water + ethanol + KCl, water + 1,2-ethanediol+ KCl, water + 2-methoxyethanol+ KC1, water + 2-ethoxyethanol+ KCl, water + l-methoxy-2-propanol+ KC1, water + 2-isopropoxyethanol+ KCl, water + 2-methoxyethanol + KBr, and water + 2-butoxyethanol + KBr. The solubility of the salt was observed to decrease with rising temperature for solvent mixtures with a high concentration of glycol ether and to increase with temperature for low glycol ether contents. Liquid-liquid equilibria of some of the salt-saturated solutions have also been determined.

Journal of Chemical & Engineering Data, 1993

A Dvoiak-Boubllk recirculating still has been used to measure isothermal vaporliquid equilibrium ... more A Dvoiak-Boubllk recirculating still has been used to measure isothermal vaporliquid equilibrium data for 1,2-ethanediol + water and for five different glycol ether + water systems. The glycol ethers are 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, 2-ieopropoxyethanol, and 2-butoxyethanol. Each system has been measured at two temperatures in the range 343.15-368.15 K. The reliability of the data has been checked by using a maximum likelihood data reduction.

Fluid Phase Equilibria, 2007

High-pressure density data for cyclohexane + n-hexadecane mixtures at a wide temperature range wa... more High-pressure density data for cyclohexane + n-hexadecane mixtures at a wide temperature range was modeled with several classical equations of state (EOS) and correlative models. A modification for softening the co-volume and another for a volume scaling of the Peng-Robinson EOS (VS-PR) were proposed. The VS-PR model is able to correlate the pure component experimental data employing only five adjustable parameters, with root-mean-square deviation (RMSD) between calculated and experimental densities essentially within the experimental error. This result is superior to widely used approaches, i.e., a six parameter Tait model and six parameter volume translations (temperature and pressure dependent) for Peng-Robinson and Patel-Teja EOS. The VS-PR model also represents well the isobaric thermal expansion and the isothermal compressibility coefficients of the pure cyclohexane, a small naphthenic substance as well as a long chain n-alkane hydrocarbon, n-hexadecane. When modeling the mixture data, the use of VS-PR model of pure components along with the Redlich-Kister expansion, truncated at the first term, the density was correlated within a RMSD only 60% greater than the experimental error. The proposed model is able to accurately represent all the tested mixture data with a relatively small number of parameters.

Environmental Technology, 2014

Environmental Science & Technology, 2004

The photo-Fenton process utilizes ferrous ions (Fe 2+), hydrogen peroxide (H 2 O 2), and ultravio... more The photo-Fenton process utilizes ferrous ions (Fe 2+), hydrogen peroxide (H 2 O 2), and ultraviolet (UV) irradiation as a source of hydroxyl radicals for the oxidation of organic matter present in aqueous effluents. The cost associated with the use of artificial irradiation sources has hindered industrial application of this process. In this work, the applicability of solar radiation for the photodegradation of raw gasoline in water has been studied. The photo-Fenton process was also applied to a real effluent, i.e., oilfield-produced water, and the experimental results demonstrate the feasibility of employing solar irradiation to degrade this complex saturated-hydrocarbon-containing system.

Ceramics International, 2014

Ternary zinc spinel oxides such as Zn 2 SnO 4 , ZnAl 2 O 4 and ZnFe 2 O 4 were synthesized and ch... more Ternary zinc spinel oxides such as Zn 2 SnO 4 , ZnAl 2 O 4 and ZnFe 2 O 4 were synthesized and characterized, and their activities in the photodegradation of phenol molecules were investigated. Zn 2 SnO 4 , ZnAl 2 O 4 and ZnFe 2 O 4 powders were synthesized by hydrothermal, metalchitosan complexation and solvothermal routes, respectively. The face-centered cubic spinel structure of each material was confirmed by powder X-ray diffractometry (XRD) and its porous structure by N 2 adsorption-desorption isotherms. The characterization of spinels was complemented with Fourier transform infrared spectroscopy (FTIR) and X-rays fluorescence (XRF), revealing the formation of spinel structures with high purity. The photocatalytic activity in the degradation of phenol was observed only with Zn 2 SnO 4 oxide. Mineralization degree of phenol molecules by Zn 2 SnO 4 photocatalyst determined by total organic carbon analysis (TOC) reached 80% at 360 min under sunlight.