Osvaldo Chiavone-Filho | Federal University of Rio Grande do Norte (original) (raw)

Papers by Osvaldo Chiavone-Filho

Fluid Phase Equilibria, 2014

Abstract This paper reports experimental activity coefficients at infinite dilution, γ i ∞ , for ... more Abstract This paper reports experimental activity coefficients at infinite dilution, γ i ∞ , for methanol, ethanol and n-hexane in three refined vegetable oils (soybean, sunflower, and rapeseed oils) measured using the dilutor technique (inert gas stripping method). The measurements were carried out in the temperature range between 313.15 and 353.15 K. Furthermore, activity coefficients at infinite dilution for various solutes (acetone, methanol, ethanol, n-hexane, cyclohexane and toluene) were measured in capric (decanoic) acid using the same technique in the temperature range from 313.13 to 353.30 K. The new data obtained for capric acid and soybean oil were compared with already published experimental data. Additionally, densities of the investigated vegetable oils were measured in the temperature range from 293.15 to 353.15 K. Using the experimental γ i ∞ values obtained over the temperature range, the partial molar excess Gibbs energy ( Δ G i E , ∞ ) , enthalpy ( Δ H i E , ∞ ) and entropy ( Δ S i E , ∞ ) at infinite dilution were determined. The relative error for the γ i ∞ measurements carried out using the dilutor technique is approximately ±2.5%. The measured γ i ∞ data in the investigated refined vegetable oils were also compared with the results of the group contribution methods original UNIFAC and modified UNIFAC (Dortmund) and an extension of the latter method to triacylglycerols was proposed.

Journal of Water Process Engineering, 2016

In this study, the activation of peroxymonosulfate (PMS) was investigated by activated carbon (AC... more In this study, the activation of peroxymonosulfate (PMS) was investigated by activated carbon (AC) along with UV for 2,4,6-trichlorophenol (TCP) degradation. The effects of operating parameters including pH, PMS concentration, AC dosage, initial TCP concentration and reaction time on TCP degradation were studied and optimized at pH 5.0, 8.0 mM PMS, 0.75 g/L AC and 75 min. Single step or two step additions of PMS made no marked difference in terms of TCP removal. The results of PMS decomposition showed that, AC/UV configuration was able to significantly activate PMS to degrade TCP compared to sole application of AC or UV. The contribution of UV in activation of PMS was more than that of AC. The rate constants of TCP degradation were in range of 0.0103-0.0512 min −1 for initial TCP concentrations of 5-50 mg/L. Scavenging experiments revealed that sulfate radical was the dominant radical of its kind for degradation of TCP, although hydroxyl radical was also partly effective. The results indicated that contribution of free radicals in solution was higher than that of surface-bound radicals. Moreover, mineralization of TCP was evaluated by COD, TOC and chlorine release and related results were 50.2%, 31.2% and 55%, respectively.

In the photo-chemical conversion of hydrogen peroxide (H2O2) into radical ⦁OH, the impact of radi... more In the photo-chemical conversion of hydrogen peroxide (H2O2) into radical ⦁OH, the impact of radiation dose (the quantum yield) on the oxidation kinetics has been properly reported, whereas the H2O2 dose is mostly treated as an attempt-and-error variable. This present work formally analyses the oxidant dose in terms of the efficiency of ⦁OH consumption by the micropollutant mineralization, which ultimately enables a generalist strategy for more cost-effective dosimetry of the oxidant. The experimental time-dependent measure of two reagents (pollutant and oxidant) and one product (CO2) enables assessment to the micro-kinetics from the perspective of the chemical dynamic. The analysis was demonstrated for photo-Fenton (FP) oxidation of hydrochlorothiazide (HCT) using a tubular photo-reactor and UVA radiation. The average value of ~ 38% was on top of the best efficiencies in association with some of the fastest rates of mineralization. Such efficiencies are demonstrated to depend on th...

International Journal of Environmental Technology and Management, 2019

Process Safety and Environmental Protection, 2019

The presence of toxic chlorinated compounds in drinking water, generated during the disinfection ... more The presence of toxic chlorinated compounds in drinking water, generated during the disinfection step in water treatment plants is of great concern for public health. Therefore, special attention has been given to the development of effective organochlorine-removal techniques. The reductive degradation via zerovalent-metals is recognized as a promising alternative. In this study, the capacity of zero-valent-copper (ZVC) containing materials to degrade 2,4,6-thichlorophenol (TCP) was investigated, using a bench-scale recirculating packed column system. The results indicate that this metal is effective for TCP degradation and dechlorination, even when derived from scrap. The kinetic model that better suits the degradation profiles is a second-order model, with an average normalized surface area rate constant (k SA ') of (2.44 ± 1.27) × 10 −3 L 2 min −1 m −2 for ZVC-containing materials. The ZVC scrap-derived material was found attractive for field applications due to its reusability and low leachability, despite its performance being affected in the presence of water natural constituents. The degradation by-products elucidated confirm that dechlorination is the main degradation pathway, leading to the formation of totally dechlorinated by-products such as phenol-like compounds and cyclohexanone. However, these may still pose a threat to aquatic organisms as revealed by toxicity assays and activity-structure relationship model (ECOSAR USEPA) predictions. Further investigation is therefore required aiming at following by-products formation with degradation time in order to find the best residence time that generates innocuous and/or adequate effluents for environmental disposal.

Fluid Phase Equilibria, 2018

Ampicillin belongs to the class of beta-lactam antibiotics, which corresponds the most prescribed... more Ampicillin belongs to the class of beta-lactam antibiotics, which corresponds the most prescribed antibiotics in medicine. This justifies the importance of elucidating the effect of several variables for the synthesis process (pH, temperature, co-solvent) on the behavior of the compounds involved in the enzymatic reaction. This paper aims to present new ampicillin solubility data in aqueous medium and the characterization of the solid phase of the antibiotic. In the phase equilibrium experiments it was considered the effect of pH (3 up to 7.5), temperature (283.15 K up to 298.15 K) and the ethanol concentration in the aqueous solution (varying between 0 and 70 wt% ethanol). The solubility curves deviate from U-shape solubility curves with respect to pH in the range of 0 to 70 wt%. This is due to ampicillin anhydrous becomes trihydrated molecule in the solid phase at alkaline pH region, changing the antibiotic properties significantly. This change in crystalline structure was confirmed by characterization of antibiotic solid phase carried out from thermogravimetric (TGA), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analyses. Dissociation constants have also been measured at the studied values of temperature and ethanol composition, using potentiometric titration. Finally, a thermodynamic model considering the ideal solution was applied to describe mathematically the solubility curves measured close to experimental uncertainties.

The Journal of Chemical Thermodynamics, 2017

Fructose (1,3,4,5,6-pentahydoxyhex-2-one) is an important sugar in the global market because of i... more Fructose (1,3,4,5,6-pentahydoxyhex-2-one) is an important sugar in the global market because of its unique characteristics when compared to other sugars, which makes fructose economically attractive, even though it is not easily produced. Crystalline fructose may be produced by crystallization of its aqueous solution, with the addition of ethanol as anti-solvent. After the separation of the crystals, the recovery of (ethanol + water + fructose) mother-liquor becomes feasible. Then, a distillation step may recover ethanol, and vapour-liquid equilibrium (VLE) data for (water + ethanol + fructose) mixtures are consequently necessary, despite not being available in the literature. In this work, VLE results for (water + ethanol) and (water + ethanol + fructose) were determined using a modified ebulliometer based on vapour recirculation. VLE measurements for (water + ethanol) were used to verify the thermodynamic consistency applying the Global Area Test developed by Redlich-Kister-Herington. Group contribution activity coefficient models were selected and evaluated to predict VLE for the ternary system. S-UNIFAC, A-UNIFAC and mS-UNIFAC models were tested. mS-UNIFAC demonstrated the best results, with average absolute relative deviation between experimental data and values calculated from the model of 0.1%, 3.6%, 3.0% and 3.6% for mole fraction of ethanol vapour when 0, 10.3, 20.7 and 31.0 mass percent of fructose were used.

Brazilian Journal of Petroleum and Gas, 2016

The aim of this work is to examine the performance of a glass column filled with a sand filter in... more The aim of this work is to examine the performance of a glass column filled with a sand filter in oil removal from oilfield produced water (OPW) and synthetic produced water (SOPW). This paper investigated the influence of process parameters such as physical characteristics of sand, column height, types of effluent (oilfield produced water and synthetic produced water), and oil concentration on oil removal efficiency. An OPW sample was taken from effluents of the oilfield unity located at Rio Grande do Norte State (Brazil), and the SOPW sample was prepared using two types of oils and salts (NaCl and KCl). The results showed that the oil concentration decreased significantly after the filtration process. The oil removal efficiency was influenced by the sand particle size and bed height, reaching 90% using a 30 cm high sand bed composed by mixed grain sizes.

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 XX Congresso Brasileiro de Engenharia Química, 2015

... Filo, 3000, Campus Universitário Lagoa Nova, Natal - RN, Brasil, CEP: 59072-970, emmanuelle... more ... Filo, 3000, Campus Universitário Lagoa Nova, Natal - RN, Brasil, CEP: 59072-970, emmanuelle@eq.ufrn.br, osvaldo@eq.ufrn ... na degradação de diversos poluentes presentes em água, tais como: benzeno, cloroetano, pesticidas e acetonas (Clarke e Knowles, 1982, Glaze ...

Journal of Chemical & Engineering Data, 2017

Growing interest in the study of production conditions in the presalt led to the need to study co... more Growing interest in the study of production conditions in the presalt led to the need to study complex systems at high pressures and temperatures, such as up to 70 MPa and up to 393 K. The aim of this work is to obtain vapor−liquid equilibrium data at high pressures and temperatures for hydrocarbon systems with carbon dioxide (CO 2). To obtain these data, an experimental setup and procedure using a synthetic cell were designed. Experimental data of the binary system CO 2 + cyclohexene (C 6 H 10) and CO 2 + squalane (C 30 H 62) over a range of temperature between 303 and 398 K and the ternary system CO 2 + C 6 H 10 + C 30 H 62 at various temperatures (318−393 K) and compositions are reported. It is noteworthy that the reported measurements in this work were not studied in the literature, and experimental data may contribute to industrial and scientific interests. The phase behavior of the system was also described using the Soave−Redlich−Kwong equation of state together with Mathias− Copeman alpha function. Interaction parameters for the attractive and repulsive terms were estimated in order to describe the experimental data within the estimated uncertainties.

In order to correlate and optimize experimental data either from the laboratory or industry, one ... more In order to correlate and optimize experimental data either from the laboratory or industry, one needs a robust method of data regression. Among the non-linear parameter estimation methods it may be pointed out of Levenberg, which applies the conversion of an arbitrary matrix into a positive definite one. Later, Marquardt applied the same procedure, calculating  parameter in an iterative form. The Levenberg-Marquardt algorithm is described and two routine for correlating vaporliquid equilibrium data for pure component and mixtures, based on this efficient method, have been applied. The routines have been written with an interface very accessible for both users and programmers, using Python language. The flexibility of the developed programs for introducing the desired details is quite interesting for both process simulators and modeling properties. Furthermore, for mixtures with electrolytes, it was obtained a coherent and compatible relation for the structural parameters of the sa...

Natural gas is an important source of primary energy that, under normal production conditions, is... more Natural gas is an important source of primary energy that, under normal production conditions, is saturated with water vapor. Water vapor increases the corrosiveness of natural gas, especially when acid gases are present. Several methods can be used to dry natural gas. The objectives of this study were to develop a procedure to absorb the water from natural gas in a new surfactant-based desiccant liquid and to evaluate gas-liquid equilibrium data. The principle of the desiccant liquid preparation is based on microemulsion formation (water-surfactant-oil mixtures). The dynamic method was applied for the determination of the equilibrium data, based on the saturation of the phases. The equilibrium criterion was the constancy in water concentration. Three surfactants were used for the natural gas water removal. The experimental results indicated the feasibility of the water removal from the natural gas using a specially designed absorption column and a desiccant liquid prepared with tur...

Environmental Science and Pollution Research, 2021

Produced water, a mixture of inorganic and organic components, comprises the largest effluent str... more Produced water, a mixture of inorganic and organic components, comprises the largest effluent stream from oil and gas activities. The removal of contaminants from this wastewater is receiving special attention of the researchers since most of them are persistent and difficult to remove with simple techniques. Several technologies from conventional to advanced oxidation processes have been employed to treat produced water. However, the achievement of greater efficiency may be conditioned to a combination of different wastewater treatment techniques. Hereupon, the present paper discusses three important aspects regarding produced water treatment: analytical methods used for characterization, relevant aspects regarding photochemical systems used for advanced oxidation processes, and combined techniques for treating oil field wastewaters. Analytical methods employed for the quantification of the main species contained in produced water are presented for a proper characterization. Photochemical aspects of the reaction systems such as operating conditions, types of irradiation sources, and technical details of reactors are also addressed. Finally, research papers concerning combined treatment techniques are discussed focusing on the essential contributions. Thus, this manuscript aims to assist in the development of novel techniques and the improvement of produced water treatment to obtain a high-quality treated effluent and reduce environmental impacts.

Journal of Chemical & Engineering Data, 2021

Monoethylene glycol (MEG) is a gas hydrate inhibitor widely applied for natural gas flow assuranc... more Monoethylene glycol (MEG) is a gas hydrate inhibitor widely applied for natural gas flow assurance. A series of density and electrical conductivity measurements of water + MEG + NaCl mixtures are reported, allowing the supervision of the MEG regeneration unit. Density (509 data points) and electrical conductivity (212 data points) measurements were performed in wide ranges of temperature, T = 278.15−363.15 K, and concentration of solvents and NaCl up to almost saturation. The theory of solutions was applied for density description using excess volume, which was correlated with the Redlich−Kister equation. The resulting absolute and relative mean deviations are 0.00127 g• cm −3 and 0.12%, indicating accurate representation. A semiempirical correlation with 15 adjustable parameters was considered for electrical conductivity of water + MEG + NaCl mixtures. The obtained absolute and relative mean deviations are 1.49 mS•cm −1 and 5.70%. The properties functions presented an approximately orthogonal behavior to each other, allowing the determination of mixture composition from experimental density and electrical conductivity data. The Matlab environment was found to be robust in solving the nonlinear system of two equations with constraints. The proposed methodology was extensively tested, and deviations less than 0.0060 and 0.0011 in solvents and NaCl mass fractions were obtained, respectively, demonstrating the required accuracy for industrial application.

Hydrochlorothiazide (HCT) is a pharmaceutical micropollutant highly toxic to the environment, bei... more Hydrochlorothiazide (HCT) is a pharmaceutical micropollutant highly toxic to the environment, being strictly mandatory to oxidize it completely toward CO2. In this context, how could the HCT oxidation via advanced oxidative processes benefit from the accelerated oxidation rates promoted by the mineralization stoichiometric excess of H2O2 ? Overall, this work elucidates the role of stoichiometric H2O2 concentration on promoting fast degradation/mineralization rates across Advanced Oxidative Processes (AOP). Employing 0.68 excess of H2O2, it was found absolute (100%) HCT degradation within 60 minutes and 95% within 30 min for UVC-H2O2 oxidation; however, the mineralization of HCT suffered limited optimization even at high H2O2 excess, being at the best performance 26.76% HCT mineralized via UVC photo-Fenton within 60 min at initial 2.00 H2O2 excess. Very presumably, the evaporation of H2O2 was the underlying reason for a low mineralization performance. Together with a detailed mathema...

Water, Air, & Soil Pollution, 2020

Creosote is a multicomponent oil classified as a dense non-aqueous phase liquid (DNAPL) produced ... more Creosote is a multicomponent oil classified as a dense non-aqueous phase liquid (DNAPL) produced from coal tar distillation. The concept of phase distribution is critical in decision-making to remediate contaminated sites. The creosote mass transfer between sorbed, aqueous, vapor, and DNAPL phases is controlled by physicochemical characteristics, geology of the site, and environment conditions. This study evaluated phase distribution of the main polycyclic aromatic hydrocarbons (PAHs) of creosote in a sandy soil with low organic matter content. The creosote was collected from a contaminated site in São Paulo, Brazil, and was characterized by gas chromatography–mass spectrometry (GC-MS). Clean soil was collected upgradient from the same area. Initially, the soil was artificially contaminated with creosote. After, the contaminated soil was put in contact with clean water in sealed vials for 72 h. Samples of the soil, vapor, and liquid phases were collected and analyzed by GC-MS. In total, 50 compounds were identified in the creosote, and 9 PAHs were selected to be studied, which represented around 30% of total creosote mass. The major contaminant concentration was detected in the sorbed phase. For instance, naphthalene mass was distributed in sorbed (33.0%), DNAPL (1.5%), aqueous (3.4%), and vapor (0.2%) phases. The results provided an understanding of the contaminant species partitioning that occurs in a real contaminated site.