Scielo RSS <![CDATA[Brazilian Journal of Chemical Engineering]]> http://www.scielo.br/rss.php?pid=0104-663220180002&lang=en vol. 35 num. 2 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[CHEMICAL POTENTIALS OF HARD-CORE MOLECULES BY A STEPWISE INSERTION METHOD]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200277&lng=en&nrm=iso&tlng=en ABSTRACT A molecular simulation algorithm was implemented to calculate chemical potentials of hard-core molecular systems at high densities. The method is based on the Widom particle insertion method and the step-function character of free energy variations. The algorithm was evaluated for hard-sphere mixtures at infinite dilution approximation by varying the solute/solvent diameter ratio, for systems with reduced densities from 0.1 to 0.8. The proposed methodology was verified by comparing simulations of trimers diluted in spheres and of single-component dimer systems with results from the literature. Then, the method was applied to mixtures of hard-spheres and dimers at several conditions regarding composition, reduced density, and bond-length/diameter ratio. The results were used to validate equations of state from the literature. The proposed approach was able to obtain accurate chemical potentials for different hard-core molecular mixtures. Lower uncertainties were obtained when comparing with traditional methods, especially at high densities. <![CDATA[N-ACETYLCYSTEINE MICRONIZATION BY THE SEDS TECHNIQUE USING SUPERCRITICAL CO<sub>2</sub>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200289&lng=en&nrm=iso&tlng=en ABSTRACT N-Acetylcysteine (NAC) is a thiol (-SH) with a strong antioxidant activity. This compound has demonstrated positive effects on chronic kidney disease, cancer, pulmonary insufficiency and other diseases. The aim of this work was to investigate the application of the Solution Enhanced Dispersion by Supercritical Fluids (SEDS) technique in the micronization of NAC using a 23 Central Composite Design (CCD) with 3 central points, as well as to assess the influence of active compound concentration, temperature and pressure on the particle size produced. The average size of the drug before SEDS processing was verified to be 709.82 µm while the best result led to a particle size of 2.86 µm, which means a reduction of about 248 fold. It was also observed that a reduction in particle size led to an increase in the dissolution rate with 100% dissolution. <![CDATA[LIQUID-LIQUID EQUILIBRIA DATA OF N-METHYL-2-HYDROXYETHYL AMMONIUM ALKYLATES WITH BUTANOL+WATER AND PENTANOL+WATER AT 293.15K, 313.15K AND 333.15K]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200299&lng=en&nrm=iso&tlng=en Abstract Ionic liquids (ILs) are organic salts with low volatility and have different applications including organic synthesis, separation and extraction processes, fuel cell electrolyte, surfactants, among others. Protic ILs based on the N-methyl-2-hydroxyethyl ammonium cation and short chain carboxylic anions have simple synthesis and purification. However, as new substances few data are available for their thermodynamic properties and phase equilibria. In order to investigate the partition of these substances in alcohol-water, liquid-liquid equilibria data were determined experimentally for three ionic liquids (formed by the cation N-methyl-2-hydroxyethyl ammonium (m-2HEA) and the anions propionate (Pr), butanoate (B) and pentanoate (P)) with butanol and pentanol, at three different temperatures: 293.15K, 313.15K and 333.15K. The binodal curves are obtained by the turbidity method with gravimetric determination of all the components, curves are fitted using the Merchuk method. The tie-lines are also gravimetrically determined. The results confirm the high hydrophilicity of these ionic liquids, with partition coefficients of water-butanol and water-pentanol lower than 1. Data were correlated with UNIFAC. <![CDATA[PVT EXPERIMENTAL AND MODELLING STUDY OF SOME SHALE RESERVOIR FLUIDS FROM ARGENTINA]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200313&lng=en&nrm=iso&tlng=en Abstract Shale reservoir fluids have been receiving much attention, especially during the last decade, due to the important reserves confirmed in many places around the world and the recent production growth in the United States, Argentina, and probably other countries to follow. In some fields of the Vaca Muerta formation in Argentina, the fluids can be classified as gas condensate or near-critical in some cases, presenting retrograde condensation of up to 30% in volume. This work presents compositional and PVT data of two gas condensate fluids, together with a new methodology for assigning molecular weights and densities to the different carbon number fractions when measured values are available for the whole fluid or liquid phase and only a weight fraction is collected through chromatography for each single cut. A thermodynamic modelling study of these fluids, and also a third one classified as volatile oil, is based on both the PR (Peng and Robinson, 1976) and RKPR (Redlich Kwong Peng Robinson, apud Cismondi and Mollerup, 2005) equations of state, together with different ways of characterizing the heavy fractions. The focus is on phase envelopes, but knowing only the saturation point at the reservoir temperature, and also on retrograde behavior. <![CDATA[OPTIMIZATION OF THE EXTRACTION OF FREE FATTY ACIDS APPLIED TO BIODIESEL PRODUCTION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200327&lng=en&nrm=iso&tlng=en Abstract The liquid-liquid extraction of free fatty acids (FFA) from residual oils and fats for biodiesel production, employing methanol as the solvent, has been optimized using process simulation and response surface methodology. The parameters investigated were temperature, number of stages and solvent-to-feed ratio (S/F). Responses evaluated were FFA mass fraction in the oil-rich phase ( w FFA B) and total cost, using yellow and brown greases as the raw materials. Quadratic and linear models were fitted for w FFA B and cost responses, respectively. The optimal conditions satisfying technical ( w FFA B ≤ 0.5%) and economic (minimum cost, including capital and operation costs, except for raw material cost) criteria were 321 K, 6 stages, S/F = 1.27, w FFA B = 0.41%, cost = $84.93/ton (yellow grease), and 318 K, 6 stages, S/F = 1.32, w FFA B = 0.49%, cost = $102.89/ton (brown grease). <![CDATA[VAPOR-LIQUID EQUILIBRIUM CALCULATION FOR SIMULATION OF BIOETHANOL CONCENTRATION FROM SUGARCANE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200341&lng=en&nrm=iso&tlng=en ABSTRACT The robustness of the simulation of bioethanol concentration from sugarcane faces two major challenges: the presence of several minor components and the nonlinear behavior of vapor-liquid equilibrium (VLE) calculations. This work assesses the effect of simplifications to overcome these difficulties. From a set of seventeen substances, methanol, n-propanol, isobutanol, 2-methyl-1-butanol and 3-methyl-1-butanol were selected through the examination of the influence of each minor component on vapor-liquid equilibrium calculations of ethanol-water-third component systems. The selection procedure was based on Txy diagrams built using the modified Raoult's law. The influence of the ratio between the vapor phase fugacity coefficients and of the Poynting correction factor were verified. The accuracy of four correlations for vapor pressure was evaluated, and two functional-group activity coefficient models were scrutinized: the recent Functional-Segment Activity Coefficient (F-SAC) and the UNIFAC-Do model. <![CDATA[THE USE OF COMPRESSED FLUIDS TO OBTAIN BIOCOMPOSITES FROM PALM OIL FIBER (<em>Elaeis</em> sp.)]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200353&lng=en&nrm=iso&tlng=en Abstract Empty fruit bunch fiber (EFBF) is a lignocellulosic waste generated by the palm oil agribusiness. The amount of EFBF produced is equal to the oil obtained, and it can be used as raw material to obtain biocomposites. The objective of this work is to fragment the EFBF employing pressurized fluids in a semi-continuous system to obtain different biocomposites. For this, pure water and a mixture of water/carbon dioxide were employed as solvent to obtain sugar monomers and a mixture of compressed water/ethanol (1:1 vol.) to obtain crystalline cellulose. The experiments were conducted in the temperature range of 120 to 240 ºC, using reaction times between 5 and 15 min at 60 bar, and solvent flow rate of 0.75 mL.min-1. A maximum of 30.47 mg.mL-1 of xylose was obtained at 210 ºC for 15 min of reaction with pure water as solvent. The best condition to obtain crystalline cellulose was 240 ºC for 30 minutes of reaction, obtaining 38.2% of cellulose from palm oil EFBF. <![CDATA[THERMODYNAMIC MODELING OF AZEOTROPIC MIXTURES WITH [EMIM][TfO] WITH CUBIC-PLUS-ASSOCIATION AND CUBIC EOSs]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200363&lng=en&nrm=iso&tlng=en Abstract Ionic liquids (ILs) are organic salts that are liquids at room temperature and have low vapor pressure. These characteristics render ILs potential substitutes of organic solvents and inorganic salts in separation of azeotropic mixtures. This work presents vapor-liquid equilibrium modeling of the azeotropic mixture acetone + methanol + 1-ethyl-3-methylimidazolium-trifluoromethanesulfonate and ethanol + water + 1-ethyl-3-methylimidazolium-trifluoromethanesulfonate with the Cubic-Plus-Association Equation of State (CPA EoS). The azeotropic ternary mixture phase behavior was properly predicted using binary interaction parameters that were adjusted from binary mixture phase equilibrium data. Results show that the CPA EoS provides a better description of experimental data as compared to the Peng-Robinson-Wong-Sandler Equation of State (PRWS EoS). <![CDATA[LIQUID-LIQUID EQUILIBRIUM OF SYSTEMS COMPOSED OF SOYBEAN OIL + MONOACYLGLYCEROLS + DIACYLGLYCEROLS + ETHYL OLEATE + OLEIC ACID + ETHANOL AT 303.15 AND 318.15 K]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200373&lng=en&nrm=iso&tlng=en Abstract Steady increase in prices of petroleum-based fuels and growing environmental concerns are boosting attention to alternative fuels. In this context, biodiesel has drawn attention as an alternative fuel, especially as a substitute to traditional diesel. Biodiesel is commonly produced from triacylglycerols and alcohol through transesterification reaction. Knowledge of equilibrium phase distribution of key components in transesterification systems is essential for a better understanding of the reaction pathway and for guiding the design and optimization of reactors and the products separation. This study reports experimental results and thermodynamic modeling of the liquid-liquid equilibrium of systems composed of soybean oil + monoacylglycerols + diacylglycerols + ethyl oleate + oleic acid + ethanol at 303.15 and 318.15 K. Experimental data were well correlated using NRTL, with a maximum deviation of 0.688%. As for UNIFAC, the deviations between predicted and experimental data ranged from 3.13 to 9.21%. <![CDATA[DENSITY, VISCOSITY AND EXCESS PROPERTIES OF BINARY MIXTURES OF PROTIC IONIC LIQUID (2-HDEAF, 2-HDEAA) + WATER AT DIFFERENT TEMPERATURES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200383&lng=en&nrm=iso&tlng=en Abstract Over the last decade, ionic liquids (IL) have attracted considerable attention for their potential to replace traditional volatile organic solvents due to their well-known physico-chemistry properties. This is an important topic for industrial applications today, and have been the subject of extensive literature studies. Nevertheless, there is still a lack of experimental thermodynamics data on aqueous mixtures, i.e., ionic liquids + water, especially volumetric and transport properties. These data could provide essential information about interactions and molecular phenomena in such mixtures. To investigate volumetric and transport properties for ionic liquids + water, density and viscosity data of the protic ionic liquids 2-hydroxydiethanolamine formate (2-HDEAF), 2-hydroxydiethanolamine acetate (2-HDEAA), water and their binary mixtures were measured at T = (293.15 to 343.15) K and atmospheric pressure. Excess molar volumes and deviation of viscosity were computed from experimental density and viscosity values and were fit to the Redlich-Kister equation. We observed a negative behavior for both ionic liquids + water mixtures that can be attributed to a shrinkage of the mixtures. <![CDATA[STRONTIUM CARBONATE SOLUBILITY DATA IN AQUEOUS MIXTURES OF MONOETHYLENEGLYCOL UNDER A CARBON DIOXIDE ATMOSPHERE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200395&lng=en&nrm=iso&tlng=en Abstract In order to inhibit natural gas hydrate formation, monoethyleneglycol (MEG) is usually injected into producing well heads. The MEG regeneration process is continuously performed at the platform. Scaling problems usually occur due to the presence of chlorides and carbonates. This work presents salt solubility data for the aqueous system with strontium carbonate, MEG and carbon dioxide. A specific analytical method was developed. Thus, experimental data for strontium carbonate (SrCO3) solubility at various carbon dioxide pressures are reported. Solubilities of SrCO3 in water were measured from 760 to 1610 mmHg at 278.15. 288.15. 298.15 and 323.15 K. For the mixed solvent (ms) conditions, solubilities were measured at 298.15 K and four isobars, i.e., 760, 1210, 1410 and 1520 mmHg. Experimental data were correlated and demonstrated to be accurate for thermodynamic modeling and process simulation. <![CDATA[SIMULATION AND EXPERIMENTAL STUDY OF METHANE-PROPANE HYDRATE DISSOCIATION BY HIGH PRESSURE DIFFERENTIAL SCANNING CALORIMETRY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200403&lng=en&nrm=iso&tlng=en Abstract Binary and ternary systems composed of methane-water and methane-propane-water, respectively, were studied using high pressure differential scanning calorimetry. The methodology was validated by comparing results for the binary system to experimental data obtained in the literature. The hydrate dissociation temperatures for the ternary system (methane-propane-water) at 21 MPa were experimentally determined for different compositions of the gas mixture and mole fractions of propane higher than 0.1 in the ternary system. Our results are in good agreement with the values predicted by applying the Cubic Plus Association (CPA) equation of state coupled with van der Waals-Platteeuw model for the hydrate phase. Although experimental results are considered satisfactory for both binary and ternary systems, higher deviations between our values and the simulated ones for the ternary system, considering peak temperature instead of the extrapolated onset as the hydrate dissociation temperature, are believed to be a consequence of dynamic effects that promote the formation of a heterogeneous hydrate and are negligible for the binary system. <![CDATA[LIQUID-LIQUID EQUILIBRIUM AND KINETICS OF ETHANOLIC EXTRACTION OF SOYBEAN OIL USING ETHYL ACETATE AS CO-SOLVENT]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200415&lng=en&nrm=iso&tlng=en Abstract This work reports a new set of experimental data for the liquid-liquid equilibrium (LLE) of the system (soybean oil + ethyl acetate + anhydrous ethanol) and the kinetics of crude oil extraction from soybean flakes using anhydrous ethanol + ethyl acetate mixtures. Data for the LLE binodal were measured at 298.15, 313.15 and 333.15K by the cloud point method and tie-lines were obtained at 298.15 and 313.15 K. LLE data were successfully modeled using the NRTL model. Batch extractions were performed at 298.15, 313.15 and 328.15 K at a fixed (4:1) solvent to soybean flake mass ratio and two concentration of ethyl acetate (5% and 10%) in ethanol. Higher temperatures increased the solubility of the system and improved the extraction yields. In addition, higher ethyl acetate ratios in anhydrous ethanol led to an increase in the total amount of crude oil extracted when operating at 298.15 and 313.15 K. At 328.15 K, no improvement in extractions was verified when 5% and 10% of ethyl acetate were used in the ethanol. A mass transfer model based on Fick’s Law was applied to describe the extraction kinetics, presenting an average relative deviation of ± 5.11%, in terms of extraction yield. <![CDATA[UTILIZATION OF AGROINDUSTRIAL BY-PRODUCTS AS SUBSTRATE IN ENDOGLUCANASE PRODUCTION BY <em>Streptomyces diastaticus</em> PA-01 UNDER SUBMERGED FERMENTATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200429&lng=en&nrm=iso&tlng=en Abstract Endoglucanase production under submerged fermentation was studied using sugarcane bagasse (SCB) and oat bran (OB) as carbon source and corn steep liquor (CSL) as nitrogen source, in different concentrations using factorial design. Streptomyces diastaticus PA-01, isolated from a soil cave in Brazil, was selected as cellulolytic strain. The results after experimental validation showed that a medium containing 2.4% (w/v) SCB and 1.3% (w/v) CSL led to the highest production, 1,180.3 U.L-1 of endoglucanase, after the 5th-day. A good level of endoglucanase (1,039.3 U.L-1) was obtained after the 4th-day when 2.0% (w/v) OB and 1.65% (w/v) CSL were used. The pH and temperature profiles showed thermoacidophilic endoglucanase activity, with 70% of maximum activity at 50ºC, after 4 hours of pre-incubation. This is the first report on endoglucanase production by S. diastaticus PA-01 in the presence of SCB and OB. The strong positive effects of some metal ions (Zn2+, Mn2+ and Ba2+) on endoglucanase activity when this strain was grown on OB is an interesting biochemical characteristic for future biotechnological applications. <![CDATA[MODEL COMPARISON TO DESCRIBE BHK-21 CELL GROWTH AND METABOLISM IN STIRRED TANK BIOREACTORS OPERATED IN BATCH MODE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200441&lng=en&nrm=iso&tlng=en Abstract Baby Hamster Kidney cells (BHK-21) are commonly used in research and the biopharmaceutical industry. This work aimed to model the kinetic performance in batch operation mode of BHK-21 cells cultured in two stirred tank configurations using different dissolved oxygen concentrations and pH control strategies. Viable and dead cell concentrations, as well as glucose, glutamine, lactate and ammonium concentrations, were monitored. Statistical multiple linear regression, logistic equation and multiplicative Monod kinetic models were fitted. Statistical models for viable cells concentration as a function of nutrient and metabolite concentrations were significant (R2 &gt;0.91). Logistic model parameters: intrinsic growth rate, cell density level in the medium and time for reaching maximum cell concentrations were within 0.061-0.083 h-1, 1.85-5.39 x 109 cell L-1 and 52-90 h ranges, respectively. A Monod-type model was satisfactorily fitted to the experimental data. Relative errors were lower than 10% for six monitored state variables in most of the assessed experimental conditions. The three models developed in this work can be used in bioprocesses involving BHK-21 with good fitting. <![CDATA[PRODUCTION OF CELLULOLYTIC ENZYMES BY <em>Gelatoporia subvermispora</em> USING DIFFERENT SUBSTRATES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200459&lng=en&nrm=iso&tlng=en Abstract In this study the solid-state fermentation for production of cellulolytic enzymes by the fungus Gelatoporia subvermispora was optimized. The enzyme activities on filter paper, exo-cellulase, endo-cellulase and xylanase were determined. A Plackett-Burman design (PB) was used to determine the most significant variables (moisture content of substrate, inoculum density, corn steep liquor concentration, pH and peptone concentration) in the enzyme production for each substrate (sugarcane bagasse, sewage sludge and rice straw). The highest value for filter paper activity was obtained using sugarcane bagasse as substrate. The sewage sludge was an excellent medium for the production of xylanase and exo-cellulases. The endo-cellulase activity was similar in all substrates tested. This is the first report of the Gelatoporia genus for the production of cellulolytic enzymes, being a promising strain for this purpose. <![CDATA[ETHANOL PRODUCTION FROM SUGAR LIBERATED FROM <em>Pinus</em> SP. AND <em>Eucalyptus</em> SP. BIOMASS PRETREATED BY IONIC LIQUIDS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200467&lng=en&nrm=iso&tlng=en Abstract Pretreatment of lignocellulosic biomass using ionic liquids (ILs) has been widely studied and is considered one of the most promising methods to obtain fermentable sugars. However, few data exist on the fermentation of reducing sugars (RS) obtained by enzymatic hydrolysis of biomass pretreated with ionic liquids for the production of ethanol. Therefore, this study evaluated the production of ethanol from sugars liberated from sawdust of Pinus sp. and Eucalyptus sp. pretreated with ionic liquid [C4mim][OAc] and [C2mim][OAc], hydrolyzed with enzymes of Penicillium echinulatum employing Saccharomyces cerevisiae and Schizosaccharomyces pombe Y698 yeasts. The data indicate that when the biomass is pre-treated by [C2mim][OAc] there is higher production of ethanol that, when treated by [C4mim][OAc] for both evaluated yeasts, even though the pretreatment with [C2mim] [OAc] caused the highest losses of cellulose and hemicellulose. Under the conditions analyzed, it is possible to produce approximately 40 and 47 L of ethanol per ton of Pinus sp. and Eucalyptus sp, respectively. In addition to contributing to knowledge about the physiology of the yeasts in the sugars liberated from biomass pretreated in presence of ionic liquid, this data is also relevant to the development of processes for the production of lignocellulosic ethanol. <![CDATA[ETHANOL PRECIPITATION AS A DOWNSTREAM PROCESSING STEP FOR CONCENTRATION OF XYLANASES PRODUCED BY SUBMERGED AND SOLID-STATE FERMENTATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200477&lng=en&nrm=iso&tlng=en Abstract Xylanases have applications in different industries, being produced by microbial cultivations using submerged (SmF) or solid-state fermentation (SSF). Precipitation stands out as a potential method for the concentration of xylanases, especially with the use as ethanol as the precipitant due to its compatibility with the biorefinery concept. This paper presents a comparative laboratory scale study of ethanol precipitation of xylanases produced by Aspergillus niger cultivated under SSF and SmF. Precipitation conditions were selected according to a central composite design. Statistical analysis showed a significant effect of pH on the recoveries of total protein and xylanase activity. The kinetic profiles showed that a relatively short period of time (up to 15 min) was sufficient to recover most of the xylanase activity precipitated under the selected conditions. Xylanase recoveries of 65 and 79% were achieved for the SSF and SmF enzymatic complexes, respectively. <![CDATA[BIOCHEMICAL RESPONSES FROM BIOMASS OF ISOLATED <em>Chlorella sp.,</em> UNDER DIFFERENT CULTIVATION MODES: NON-LINEAR MODELLING OF GROWTH KINETICS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200489&lng=en&nrm=iso&tlng=en Abstract In this study, the effect of different modes of cultivation viz., photoautotrophic (AT), heterotrophic (HT) and photomixotrophic (MT), on the growth and biochemical responses of Chlorella sp. isolated from local ponds. The performance of microalgal growth was quantified using nonlinear growth models such as Gompertz, logistic, Baranyi-Roberts, Morgan under different cultivation conditions. The results revealed that microalgae could grow better in MT than in other cultivation modes with a major increase in biochemical responses for carbohydrates, which showed higher accumulation under HT. The maximum biomass concentration was 1.24 g L-1 (MT), 1.16 g L-1 (HT), 0.76 g L-1 (AT) with maximum specific growth rates of 0.0083 h-1 (HT), 0.0078 h-1 (MT) and 0.0055 h-1 (AT) respectively. The biomass concentration was higher in the order of MT&gt;HT&gt;AT for which MT yielded 8.8 fold higher biomass, compared with the initial biomass concentration, at the end of experiments (16 days). Concomitant increases in biochemical responses were observed in the three cultivation conditions. Protein and lipid accumulation in the MT mode was higher (1.2 fold) compared with the initial protein yield as well as the other cultivation modes. However, the carbohydrate yield was higher (1.12 fold) in the heterotrophic mode than in other cultivation conditions. <![CDATA[ASSESSMENT OF KINETIC AND METABOLIC FEATURES OF TWO HYBRIDOMAS IN SUSPENSION CULTURE FOR PRODUCTION OF TWO MONOCLONAL ANTIBODIES FOR BLOOD TYPING]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200497&lng=en&nrm=iso&tlng=en Abstract The aim of this study was to analyze kinetic and metabolic features of two hybridomas for monoclonal antibodies (MAbs) production for blood typing. Two lines of hybridomas, ED7 and ED9, were evaluated to produce anti-A and anti-AB, respectively. Experiments with ED7 and ED9 lines were conducted in a 500mL spinner flask and 2L bioreactor, using two different basal culture media, both with 10 % v/v addition of fetal bovine serum. The results revealed the necessity of additional supplementation of the culture media to meet the nutritional demands of the cells. Through nutritional balance and cultivation in better controlled conditions in the bioreactor, it was possible to raise the maximum specific growth rate µmax in 8.2 % and the productivity of anti-A in 148 % with the line ED7. For the ED9 line the µmax decreased 9.5% but the productivity of anti-AB increased 33.3%. <![CDATA[CAROTENOID PRODUCTION BY <em>Sporidiobolus pararoseus</em> IN AGROINDUSTRIAL MEDIUM: OPTIMIZATION OF CULTURE CONDITIONS IN SHAKE FLASKS AND SCALE-UP IN A STIRRED TANK FERMENTER]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200509&lng=en&nrm=iso&tlng=en Abstract Biotechnological production of carotenoids can be affected by cultivation conditions, such as temperature, pH and agitation. The aim of this study was to maximize carotenoid production by Sporidiobolus pararoseus in shake flasks with agroindustrial by-products as substrates. The best conditions were used in a stirred tank fermenter. The medium consisted of corn steep liquor and sugar cane molasses pretreated with sulfuric acid. In order to evaluate the effects of the variables, a central composite rotatable design was used. The highest values of total carotenoids (565 µg L-1), biomass (13.6 g L-1) and Yp/s (10.9 µg g-1) were obtained in Assay 13 at 27.5ºC, 150 rpm and pH=4, in Erlenmeyer flasks. For the best conditions defined for carotenoid productivity and 1.2 vvm in the stirred tank fermenter, the maximum value was 1969.3 µg L-1 of total carotenoids. It was 3.5-fold higher than the value obtained when shake flasks were used. <![CDATA[ORGANOPHOSPHATE ESTERS REMOVAL BY UV/H<sub>2</sub> O<sub>2</sub> PROCESS MONITORED BY <sup>31</sup>P NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200521&lng=en&nrm=iso&tlng=en Abstract The present work aims to study the photocatalytic degradation of three organophosphate esters considered environmental emerging contaminants by the UV/H2O2 system with the use of 31P NMR spectroscopy to investigative their removal after the treatment. Results demonstrated the efficiency of the oxidation system in removing the esters tris(2-butoxyethyl) phosphate (TBEP), tris(2-chloroethyl) phosphate (TCEP) and tri-butyl phosphate (TBP) from aqueous solutions when they were individually present and mixed. High levels of degradation of these chemicals were achieved, in addition to the good performance of the analytical technique applied in the study, which represents some advantages in comparison with other techniques reported in the literature. An increase in the 31P NMR signal removal could also be observed when the oxidizing agent concentration increases. Decreases in solution acute toxicity were also verified for both TBP and TBEP treated samples when compared with the samples before the treatment. <![CDATA[TREATMENT OF WASTEWATER WITH HIGH FAT CONTENT EMPLOYING AN ENZYME POOL AND BIOSURFACTANT: TECHNICAL AND ECONOMIC FEASIBILITY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200531&lng=en&nrm=iso&tlng=en ABSTRACT The combination of 0.5% weight per volume (w/v) crude enzyme consortia produced by solid state fermentation with Penicillium brevicompactum and 27 milligrams per liter (mg/L) of rhamnolipid biosurfactant produced by submerged fermentation with Pseudomonas aeruginosa was employed to pretreat wastewater from a poultry slaughterhouse in bench upflow anaerobic sludge blanket (UASB) bioreactors. One bioreactor was fed with untreated wastewater (Control) and another with pretreated wastewater (Test). Under an organic loading rate of 11 kg COD/m3.d, the Test bioreactor showed higher specific methane production (67.8 mL CH4 (STP)/g COD removed), higher chemical oxygen demand (COD) (91.2%), and oil and grease (O&amp;G) (95.8%) removal than the Control bioreactor, which produced 36.1 - 16.9 mL CH4 (STP)/g COD removed with 72.5% COD removal and 48% O&amp;G removal. The Control bioreactor experienced five clogging episodes due to the accumulation of fat on the surface, while the Test bioreactor operated without operational problems. The scum of the Control bioreactor contained more than 10 times higher quantities of fat than the Test bioreactor. The economic analysis indicated that such alternative technology has lower costs than conventional technology. <![CDATA[ACID MINE DRAINAGE TREATMENT AND METAL REMOVAL BASED ON A BIOLOGICAL SULFATE-REDUCING PROCESS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200543&lng=en&nrm=iso&tlng=en ABSTRACT The key purpose of this research was to explore the capacity of an anaerobic stirred batch reactor (ASBR) to deal with acid mine drainage (AMD) based on the activity of sulfate reducing bacteria (SRB). The tests showed that SRB produced hydrogen sulfide that precipitated the metals Fe2+, Zn2+, and Cu2+. Ethanol was used as both the only source of carbon and electron donor. Throughout the experiment, the ratio of chemical oxygen demand (COD) to sulfate was constant at 1.0. The reactor was operated for 218 days using synthetic AMD at pH 4.0 containing 1000 and 1500 mg·L-1of sulfate,100 mg·L-1of Fe2+, 20 mg·L-1Zn2+, and 5 mg·L-1Cu2+. The metal removal rates were greater than 99% with effluent pH of 6.5 to 7.4. The sulfide concentration reached 56.6 mg·L-1 and sulfate removal was 43 to 65%. <![CDATA[SIMULATED DAIRY WASTEWATER TREATMENT IN A PILOT PLANT SCALE MAGNETO-ACTIVE HYBRID ANAEROBIC BIOFILM REACTOR (MA-HABR)]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200553&lng=en&nrm=iso&tlng=en Abstract The aim of this study was to determine the effects of magneto-active microporous packing media manufactured by extrusion technology and modified by the addition of relevant amounts of metal catalysts and magnetic activation on the effectiveness of simulated dairy wastewater (SDW) treatment and biogas productivity in a pilot plant scale hybrid anaerobic biofilm reactor with full mixing. The best performance was found at an organic loading rate (OLR) in the range 6.0 - 8.0 kg COD/m3·d, where the chemical oxygen demand (COD) removal was about 80%, the biogas yield ranged from 256.7 - 310.9 L/kg CODremoved, the methane production ranged from 420.6 - 557.1 L/d and total phosphorus removal ranged from 82.9 - 90.7%. The study demonstrated that the application of the innovative packing media in the biofilm-bed reactor enhanced the sorption of organic matter, biogas productivity and the binding of biogenic compounds. <![CDATA[TREATMENT OF WASTEWATER FROM BIODIESEL GENERATION AND ITS TOXICITY EVALUATION BY <em>Raphidocelis subcapitata</em>]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200563&lng=en&nrm=iso&tlng=en ABSTRACT Biodiesel was developed to solve vast economic and environmental problems related to the use of petroleum as fuel. However, large quantities of water are necessary for biodiesel production, generating a high volume of effluent waste. Therefore, it is important to treat this wastewater in order to meet the environmental legislations according to the Brazilian Resolution Number 430/2011 (CONAMA). This work aimed to treat this effluent by coagulation/flocculation (CF) and an electrochemical advanced oxidation process. The combination of CF techniques (pH = 6.5) and electrochemical oxidation (boron doped diamond - BDD - electrode with NaCl) led to 78.5% removal of total organic carbon. The evaluation of the toxicity with Raphidocelis subcapitata indicated that the treated samples (IC5072h = 1.66%) had higher chronic toxicity when compared to raw effluent samples (IC5072h = 0.17%). This indicates that the proposed treatment was effective to decrease the organic load and reduce the environmental impact of these effluents in water bodies. <![CDATA[DEPENDENCY OF NANOFLUID RHEOLOGY ON PARTICLE SIZE AND CONCENTRATION OF VARIOUS METAL OXIDE NANOPARTICLES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200575&lng=en&nrm=iso&tlng=en Abstract Impact of the nanoparticle size and concentration on the rheology of ethylene glycol based nanofluids containing nanoparticles of five different metal oxides is investigated. Particle mass concentrations ranged from 5 to 20 wt %. Types of the nanoparticles and their particle size are TiO2 (30 nm, 50 nm), MgO (20 nm, 40 nm), ZnO (10-30 nm, 35-45 nm, 80-200 nm), SiO2 (20-30 nm, 60-70 nm) and CuO (40 nm, 80 nm). A stress controlled rheometer fitted with a cone-and-plate system is employed for the rheological characterization of the nanodispersions at temperatures between -5˚C and 35˚C. The non-linear measurements reveal that nanofluids of CuO (40 nm), ZnO (10-30 nm, 35-45 nm) and MgO (20 nm, 40 nm) particles exhibit non-Newtonian shear thinning behavior at particle mass concentrations higher than 5 %. No appreciable shear thinning is observed for the dispersions of TiO2 (30 nm, 50 nm) and SiO2 (20-30 nm, 60-70 nm) particles. Strong dependency between relative viscosity of the suspensions and particle size and loading is observed. Temperature, on the other hand, plays a marginal role in the relative viscosity of the suspensions. The shear viscosity measurements indicated the presence of particle size and concentration dependent apparent yield stress for CuO and ZnO nanofluids. Investigated nanofluids do not exhibit any thixotropy during their rheological characterization. Finally, viscoelastic measurements suggest that nanofluids are free of gel formation. <![CDATA[EFFECT OF FLUIDIZED-BED PROCESS VARIABLES ON CONTROLLED-RELEASE OF NITROGEN AND COATING]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200587&lng=en&nrm=iso&tlng=en Abstract Pristine urea is lost due to ammonia volatilization and leaching causing toxic emissions and eutrophication. Controlled-release urea is employed as an abatement strategy. Most of the synthetic polymers used to produce controlled-release urea are non-biodegradable and expensive. To offset this problem, modified-starch biopolymer is used as coating material to produce controlled-release urea in fluidized bed. The effect of different process variables is studied on release characteristics and coating uniformity of coated urea. The product has better release characteristics. The statistical analysis reveals that fluidizing gas temperature and coating time are the most influential variables. The nutrient release time increases with increase in coating time and decreases with increase in fluidizing gas temperature beyond a certain limit. Coating uniformity, significant thickness and film integrity are required for promising release characteristics. Urea release followed non-Fickian diffusion and Case-II transport. This study can help produce green fertilizer at bigger scale. <![CDATA[LIQUID-LIQUID EXTRACTION OF AROMATICS FROM HYDROCARBON MIXTURES IN CAPILLARIES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200605&lng=en&nrm=iso&tlng=en Abstract An aromatics extraction study was conducted in capillaries of internal diameters in the range of 0.8 mm to 2 mm. The systems chosen for study were ‘n-heptane + toluene + propylene carbonate’, ‘n-heptane + toluene + furfural’ and ‘synthetic naphtha reformate + (propylene carbonate + tetraethylene glycol)’. The aim of the work was to evaluate the feasibility of conducting aromatic separation in micro-capillaries and evaluate maximum efficiency. The results showed efficiencies ranging from 46.3 % to 97.3 %, depending upon the combination of the flow velocity, residence time and channel diameter. The effect of individual parameters on extraction efficiency was also isolated from the various combinations. Efficiency increased from 68 to 83 % as flow velocity increased from 0.11 to 0.96 cm/s, while residence time and channel diameter were fixed at 0.78 min and 2 mm, respectively. The samples collected from the capillary quickly separated into clear liquid layers, indicating short settling times. <![CDATA[CONVECTIVE-DIFFUSIVE HEAT TRANSFER IN TUBES: ROLE OF THE HYDRODYNAMICS OF FLOW ON THE FEASIBILITY DOMAIN OF THE ASYMPTOTIC TEMPERATURE PROFILES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200615&lng=en&nrm=iso&tlng=en Abstract In this contribution, an assessment of the role of the hydrodynamics of flow on the asymptotic solutions used to describe convective-diffusive heat transfer in packed-bed and capillary tubes of cylindrical geometry is reported. Such asymptotic solutions are intrinsically dependent from the type of hydrodynamics present in the tubes. They describe the temperature profiles for heat transfer problems found in packed-bed and capillary systems with axial convective and radial diffusive transport and having a constant heat flux at the outer tube wall. The role of the hydrodynamics of the flow on the asymptotic temperature profiles and their feasibility region of validity for both the packed-bed and capillary tube cases were assessed and feasibility ranges identified. A brief comparison of the predictions for the two cases analyzed is also included. The analysis of the impact of the hydrodynamics on the ranges of validity for the asymptotic temperature profiles seems to be first one available. <![CDATA[SYNTHESIS OF ZEOLITE 4A FOR OBTAINING ZEOLITE 5A BY IONIC EXCHANGE FOR FULL UTILIZATION OF WASTE FROM PAPER INDUSTRY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200623&lng=en&nrm=iso&tlng=en Abstract In order to minimize environmental impact zeolite A was synthesized using waste from the paper industry. This waste is composed of cellulose, kaolin and calcium carbonate. Waste purification was carried through thermal and chemical treatment, which consisted of initial calcination, acid washing with HCl, then calcination of the solid fraction to obtain metakaolin and evaporation of the liquid fraction to obtain CaCl2. Zeolite 4A was produced by static autoclaving under hydrothermal synthesis at different temperatures, crystallization times and NaOH concentrations. As a source of aluminum and silicon metakaolin was used. The synthesis of zeolite 5A was performed by ion exchange with CaCl2. After that, the waste paper (in natura and HCl treatment) and the zeolites 4A and 5A were characterized by XDR, SEM, FTIR, AAS and thermal analysis. The temperature is a key factor in zeolite synthesis at lower concentrations allowing one to obtain zeolite 5A by ion exchange with zeolite 4A. <![CDATA[EFFECT OF STIRRING SPEED ON CONVERSION AND TIME TO PARTICLE STABILIZATION OF POLY (VINYL CHLORIDE) PRODUCED BY SUSPENSION POLYMERIZATION PROCESS AT THE BEGINNING OF REACTION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200631&lng=en&nrm=iso&tlng=en Abstract The effect of changes in the stirring speed during suspension polymerization of vinyl chloride monomer (VCM) was investigated near the particle stabilization. Preliminary tests were conducted to check the highest conversion and information regarding the porosity and particle stabilization of two formulations, which are based on different concentrations of initiators and dispersing agents. The influence of stirring speed during the first 2 h of reaction was investigated for the best formulation, indicating that there was a proportional relationship between the increase in speed and the increase in conversion. The results presented suggest that the highest stirring speeds (900 and 1000 rpm) tended to achieve the same conversion with increasing reaction time. This was also observed with the lower stirring speeds (600 and 700 rpm); however, the conversions obtained were lower than those found with higher stirring speeds. The conversions achieved in 20 to 30 min of reaction were similar for all stirring speeds studied (20 min: 4.8% ± 1.3%; 30 min: 7.5% ±1.4%). However, there was greater variation in conversion for longer reaction times (60 min: 15.9 ± 2.8%; 120 min 36.5 ± 2.4%). Stability of the particles was achieved for 6-8% conversion for all stirring speeds used when breakage and coalescence processes stop. The conversion interval obtained in this work was smaller than the values found in the literature (between 15 and 20%). The effect of stirred conditions on particle size distribution showed that better stability of the particle size occurred at 900 rpm for the system studied. In this case, variations in the particle size decreased when the conversion increased. <![CDATA[HYDRODYNAMIC CHARACTERISTICS OF A STRUCTURED BED REACTOR SUBJECTED TO RECIRCULATION AND INTERMITTENT AERATION (SBRRIA)]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200641&lng=en&nrm=iso&tlng=en ABSTRACT This work aimed at evaluating the effect of recirculation ratio on the degree of mixing in the flow of a structured bed reactor. Stimulus-response assays were carried out with hydraulic retention times of 6 h and 12 h, subjected to recirculation ratios of 0, 1, 2, 3, and 4. The assays were undertaken with dextran blue as a tracer and without aeration. The results fitted a compartment model, allowing the determination of the mixed-flow and plug-flow volumes inside the reactor. The model application showed that recirculation ratios between 1 and 3 do not increase the mixed-flow volume of the reactor. Higher mixed-flow volumes were obtained at recirculation rates higher than 4 for both 6 h and 12 h of hydraulic retention times. The results obtained in this research are important for future applications of this reactor configuration, promoting a mixed flow in the reactor with a minimum recirculation ratio. <![CDATA[CELLULASE IMMOBILIZATION ON POLY(METHYL METHACRYLATE) NANOPARTICLES BY MINIEMULSION POLYMERIZATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200649&lng=en&nrm=iso&tlng=en Abstract Cellulases are efficient enzymes for the conversion of cellulose into glucose. Their use in immobilized form enables them to be reused in successive cycles in many biotechnological processes. Unlike conventional methods of immobilization by covalent bonding, in miniemulsion polymerization the immobilization of enzyme and the synthesis of polymer nanoparticles (support) occur simultaneously. Based on these aspects, the immobilization of cellulose on poly(methyl methacrylate) (PMMA) nanoparticles by miniemulsion polymerization was studied. The surfactant type (non-ionic and ionic) and latex pH showed great influence on cellulase activity. High activity values were obtained only when non-ionic surfactant (Lutensol AT50) and buffering agent (NaHCO3) were used simultaneously. MMA polymerization rate and final monomer conversion were not affected by the presence of cellulase. The maximum immobilization efficiency (60%) was obtained when 6 wt.% of cellulase was used and stable PMMA nanoparticles (133 nm) were obtained. The relative activity profile of immobilized cellulase, for pH as well as temperature, was similar to that reported for the free form. Immobilized enzyme keeps its activity throughout seven days when stored at 4 ºC and phosphate buffer pH 6.0. Based on the results obtained in this work, miniemulsion polymerization as a method for cellulase immobilization on PMMA nanoparticles showed to be a promising technique with high possibility of industrial application. <![CDATA[SELECTIVE CHLORINATION OF GLYCEROL TO 3-CHLORO-1,2-PROPANEDIOL CATALYZED BY BRØNSTED ACIDIC IONIC LIQUIDS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200659&lng=en&nrm=iso&tlng=en Abstract Brønsted acidic ionic liquids composed of 1-butyl-3-methylimidazolium, triethylbutylammonium, and 1-butylpyridinium cation counterparts and HSO4‾ and H2PO4‾ anion counterparts were used as the catalysts for the selective chlorination of glycerol with hydrogen chloride to 3-chloro-1,2-propandiol. From the perspective of the glycerol conversion and product yields, the catalytic activities of the ionic liquids containing HSO4‾ were higher than the ionic liquids containing H2PO4‾. As compared with the carboxylic acid catalysts, Brønsted acidic ionic liquids favored the catalytic chlorination of glycerol to 3-chloro-1,2-propandiol. When the glycerol chlorination was catalyzed by the Brønsted acidic ionic liquids at 110 ºC for 12 h with the catalyst loading of 0.75 mol·kg‾1 glycerol, the 3-chloro-1,2-propandiol yield was more than 81% at the complete conversion of glycerol. <![CDATA[HYDROTALCITE-IMPREGNATED COPPER AND CHROMIUM-DOPED COPPER AS NOVEL AND EFFICIENT CATALYSTS FOR VAPOR-PHASE HYDROGENATION OF FURFURAL: EFFECT OF CLAY PRETREATMENT]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200669&lng=en&nrm=iso&tlng=en Abstract A series of novel catalysts based on immobilization of copper and chromium-doped copper on calcined and uncalcined hydrotalcite support have been developed and used for promoting vapor-phase hydrogenation of furfural. The results indicated that a pre-calcination of the support has a negative role in changing the structural features and catalytic activity of the final catalysts. Moreover, the presence of the Cr promoter can improve the catalyst performance. The best performance (furfuryl alcohol selectivity of 94% and furfural conversion of 89%) was obtained over the Cr-doped copper catalyst supported on as-synthesized hydrotalcite material. <![CDATA[THEORETICAL MODELS FOR RATES OF HETEROGENEOUS REACTIONS DURING COMBUSTION AND GASIFICATION OF LIQUID FUELS IN FLUIDIZED BEDS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200679&lng=en&nrm=iso&tlng=en Abstract Two mathematical models to allow computations of chemical species production or consumption rates by heterogeneous reactions taking place during combustion and gasification of liquid fuels sprayed on or injected into fluidized beds of solid particles are proposed. The possibilities envisaged here are called: the CIP (Coated Inert Particles) and the CSP (Coke Shell Particle) models. The former assumes that the injected liquid fuel immediately coats the fluidized inert particles in the bed and then goes through pyrolysis, combustion and gasification reactions. The latter presumes that the liquid fuel drops go through fast pyrolysis before meeting any inert particles and the remaining coke hollow particles react with gases in the bed. Analytical solutions for various geometries of the inert particles in the bed are presented. The work does not include the governing equations which constitute the whole mathematical model of fluidized-bed reactors. Such can be found elsewhere. The present work concentrates only on the theoretical aspects. Experimental tests would allow verification if they properly represent the processes of liquid consumption during combustion and gasification processes consuming liquid fuels in fluidized beds and which model would better fit each individual situation. <![CDATA[DEVELOPMENT OF ANTIOXIDANT POLY(THIOETHER-ESTER) NANOPARTICLES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200691&lng=en&nrm=iso&tlng=en Abstract Poly(Thioether-Ester) nanoparticles synthetized via thiol-ene polymerization from a renewable castor oil monomer are produced by miniemulsion polymerization and emulsification/evaporation of pre-formed polymer. Its antioxidant activity, probably due to the oxidation of sulfide groups, is confirmed by 2,2-diphenyl-1-picryl hydrazyl (DPPH) free radical-scavenging and β-carotene/linoleic acid assays, with an amount of polymer required to reduce the initial concentration of DPPH· radicals by 50% of ~195 µg.ml-1 promoting hydrogen or electron exchange and the capability to prevent lipid peroxidation of ~55%. The results show a promising application in food packing. <![CDATA[PRODUCTION OF CASTOR OIL MALEATE USING DI-TERT-BUTYL PEROXIDE AS FREE RADICAL CATALYST]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200699&lng=en&nrm=iso&tlng=en Abstract Castor oil maleate is used in healthcare products, synthetic lubricants, drying oils, water-soluble paints and as a monomer in several polymers. This compound is formed by direct reaction between castor oil and maleic anhydride, which can be accelerated using free radical catalysts. In this work, the influence of processing temperature and the concentration of di-tert-butyl peroxide (DTBP) in the production of castor oil maleate was studied applying response surface methodology. The results showed that the use of the radical initiator increased the rate of reaction, leading to a shorter reaction time and higher productivity. The optimal operating condition was found at 120ºC, 1 mol of maleic anhydride/mol of castor oil and 0.005 mol of DTBP/mol of castor oil, yielding 90.2% of castor oil maleate in 90 min. <![CDATA[PREPARATION OF MICRON-SIZED DROPLETS AND THEIR HYDRODYNAMIC BEHAVIOR IN QUIESCENT WATER]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200709&lng=en&nrm=iso&tlng=en Abstract To study the hydrodynamics of rising droplets (especially less than 1 mm) in quiescent water, a microfluidic device with co-flowing configuration was integrated to prepare micron-sized droplets. Soybean oil and toluene droplets of size from 100 to 600 µm were obtained by five co-flowing devices with different capillary sizes. It is found that the capillary device with smaller tip size produces smaller droplets and, for a given device, the droplet size decreases with the increase of continuous phase flow rate. Alternatively, the increase of dispersed phase flow rate has little influence on the droplet size. To predict the droplet size, a correlation for dimensionless droplet diameter as a function of Capillary number (Ca), Reynolds number (Re) and viscosity ratio was proposed. Then, the hydrodynamics of a single droplet and of droplet swarms rising in quiescent water were extensively investigated. The experimental results show that the terminal velocity of a single micro-droplet is consistent with that of rigid spheres with the same size and density, while the terminal velocity of a droplet swarm is obviously higher than that of a single droplet. Experimental observation shows that the motion of a droplet swarm in static water is such a manner that each droplet alternately accelerates by chasing others, causing a higher terminal velocity. Furthermore, the terminal velocities of millimeter-sized toluene droplets rising in water were measured. Compared with rigid spheres, the droplets of dp=1~4.6 mm have higher terminal velocities, while the droplets of dp&gt;4.6 mm have lower terminal velocities. Finally, by taking into account the interfacial tension, internal circulation and shape deformation, a comprehensive explanation is proposed to describe the variation of the drag coefficient with the droplet size ranging from microns to millimeters. <![CDATA[FABRICATION OF SPINEL COATING ON HP40 ALLOY AND ITS INHIBITION EFFECT ON CATALYTIC COKING DURING THERMAL CRACKING OF LIGHT NAPHTHA]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200721&lng=en&nrm=iso&tlng=en Abstract A novel two-step process of Cr-Mn pack cementation and thermal oxidation was applied to fabricate a MnCr2O4 spinel coating on HP 40 alloy. The Cr-Mn diffusion layer formed after the Cr-Mn pack cementation process is lacking in Fe and Ni. A dense and uniform coating formed on the alloy following thermal oxidation. The coating is mainly composed of MnCr2O4 spinel phase, while the outer surface of the coating is completely MnCr2O4 spinel. The coating exhibits a favorable thickness of about 7 µm according to SEM and EDS maps of its cross-section. The MnCr2O4 spinel coating significantly affects the coking mechanism and coke property according to coking experiments. Raman spectroscopy shows that the coated sample inhibits catalytic coke formation as more disordered carbon and amorphous carbon layers are present. Moreover, the coating is stable in coking and decoking environments. <![CDATA[PREDICTING THE PENETRATION AND NAVIGATING THE MOTION OF A LIQUID DROP IN A LAYERED POROUS MEDIUM: VISCOUS FINGERING VS. CAPILLARY FINGERING]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200731&lng=en&nrm=iso&tlng=en Abstract In this paper, penetration of a liquid drop in a layered porous medium as well as its motion navigation was investigated using the lattice Boltzmann method (LBM). The porous medium was generated by locating square obstacles randomly in the each layer which would cause the layered porosity in the domain. Two regimes of penetration; (a) capillary fingering regime and (b) viscous fingering regime were used for this study. The relationship between the porosity and the penetration rate was studied. The effect of porous surface type (i.e., hydrophobicity or hydrophilicity) on the penetration rate and penetration pattern was also investigated. A new parameter, called “Percent of hydrophobicity”, was defined such that each layer of the porous medium could have multiple properties. This means that in each layer some solid elements might be randomly hydrophobic or hydrophilic. Using this hydrophobicity coefficient, one could navigate the motion of the liquid in such porous media. <![CDATA[SOFT SENSOR MODELS FOR A FRACTIONATION REFORMATE PLANT USING SMALL AND BOOTSTRAPPED DATA SETS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200745&lng=en&nrm=iso&tlng=en Abstract In refinery plants key process variables, like contents of process stream and various fuel properties, need to be continuously monitored using adequate on-line measuring devices. Such measuring devices are often unavailable or malfunction and, hence, laboratory assays which are irregular and time consuming and therefore not suitable for process control are inevitable alternatives. This research shows a comparison of different soft sensor models developed from a small industrial data set with soft sensor models developed from data generated by a bootstrap resampling method. Soft sensors were developed applying multiple linear regression, multivariable adaptive regression splines (MARSpline) and neural networks. The purpose of the developed soft sensors is the assessing of benzene content in light reformate of a fractionation reformate plant. The best results were obtained by the neural network-based model developed on bootstrapped data. <![CDATA[OPTIMIZATION OF KINETIC LUMPING MODEL PARAMETERS TO IMPROVE PRODUCTS QUALITY IN THE HYDROCRACKING PROCESS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200757&lng=en&nrm=iso&tlng=en Abstract In this study a typical continuous lumping model with five parameters has been used for kinetic modeling of thermal and catalytic hydrocracking. Model parameters have been optimized according to experimental product distributions using a particle swarm optimization (PSO) algorithm. Experimental data from the hydrocracker setup have been employed to validate the proposed model. In this setup hydrogen and vacuum gasoil feed were introduced from the top of a vertical reactor and, after passing through a catalyst bed, the liquid and gas products were separated and analyzed. Temperature of the reactor was adjusted in the range of 440-470°C for thermal hydrocracking, and 410-430°C for catalytic hydrocracking. Liquid hourly space velocities (LHSV) were in the range of 0.5-1.5 feed flow rate per catalyst volume in both sets of experiments. Results of optimization showed that the parameters were only temperature dependent. The comparison between model results and experimental data indicates that the model is capable of predicting product yield with maximum errors of 0.986 and 0.041 for RMSE and AARE values, respectively. <![CDATA[OPERATIONAL DESIGN AND IMPROVEMENT OF CONVENTIONAL BATCH DISTILLATION AND MIDDLE-VESSEL BATCH DISTILLATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200769&lng=en&nrm=iso&tlng=en Abstract Conventional batch distillation and middle-vessel batch distillation were studied for the separation of the ternary system of cyclohexane/n-heptane/toluene, which has low relative volatilities. The modified variable and constant reflux operations were applied in the conventional batch distillation. Two control structures were used: one of which was referred to as the composition control structure with a modified level-set point, and the other was referred to as the flowrate-limiting control structure. Thus, the middle-vessel batch distillation was able to simultaneously separate the components of the ternary mixture. Comparing the two control structures showed that the flowrate-limiting control structure was better than the composition control structure with a modified level-set point in terms of their applicability. Disturbances were introduced to assess the controllability of the flowrate-limiting control structure. The dynamic responses demonstrated that the control structure performed well. The results showed that the modified conventional batch distillation and middle-vessel batch distillation increased the purity of the separated components compared to previous studies. <![CDATA[EXTRACTION OF RICE BRAN OIL USING SUPERCRITICAL CO<sub>2</sub> COMBINED WITH ULTRASOUND]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200785&lng=en&nrm=iso&tlng=en Abstract Rice bran oil (RBO) contains oryzanol and tocopherols. Its recovery was performed using conventional techniques with toxic solvents that leave residues in the final product. Supercritical fluid extraction (SFE) has been used, obtaining high global yields without residual solvent. This work proposes to use ultrasound to enhance the kinetics of the RBO extraction using supercritical CO2. The factors considered were ultrasound power (160 to 320 W) and sonication time (40 to 120 min), at 40 ºC and 25 MPa. The best condition (160 W / 40 min) resulted in a 12.65 wt% extraction yield. When ultrasound was not used, the global yield dropped to 9.94 wt%, representing an increase of 27% of global yield due to ultrasound application. This increase can be assigned to the vibration effect promoted by the ultrasonic waves at the interfaces between the solid matrix and solvent. The extracts showed antioxidant activity towards the DPPH radical achieving values around 70% of inhibition. Precursors of oryzanol (campesterol, β-sitosterol, stigmasterol and 4-methylenecycloartanol) were identified in the SC-CO2 + US extracts. The results presented herein showed that SC-CO2 + US is a promising technology to be employed for the extraction of bioactive compounds. <![CDATA[COMPARATIVE STUDY FOR ADSORPTION OF HYDROGEN-METHANE MIXTURES ON ACTIVATED CARBON AND 5A MOLECULAR SIEVE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200795&lng=en&nrm=iso&tlng=en Abstract Equilibrium adsorption isotherms were obtained experimentally by a static method for a binary component hydrogen-methane mixture on activated carbon and 5A molecular sieve adsorbents. The temperature range 303-333 K and pressure range 0 - 4 MPa were examined. Methods for predicting gas-mixture equilibrium adsorption data from the pure-component isotherms were evaluated. Extended Langmuir model correlated the adsorption of binary mixtures fairly well. In all cases mutual interference was found, that is, the amount of a given gas adsorbed at a given partial pressure was always less in the mixture than it would have been if the other gaseous component had not been present. It was found that the amount adsorbed of gases per unit bulk volume for 5A molecular sieve was higher than for activated carbon. Furthermore, 5A molecular sieve showed better adsorption characteristics than activated carbon in mass transfer properties, affinity, selectivity and heat of adsorption. <![CDATA[DEVELOPMENT AND OPTIMIZATION OF A SINGLE-STEP CATION CHROMATOGRAPHIC WHEY PROTEIN FRACTIONATION PROCESS: EVALUATION AND COMPARISON OF SCALE-UP STRATEGIES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200805&lng=en&nrm=iso&tlng=en Abstract This manuscript presents evaluation of various strategies used for the scale-up of chromatographic purification systems. Towards that end, the manuscript provides development and optimization of a single-step whey protein concentrate (WPC) fractionation process at lab scale on a 1.0 × 19 cm column using UNOsphere S. Subsequently, scale-up of this newly developed process and conduction of trials at higher scale is also undertaken by applying various scale-up strategies. For these trials, this work categorized various scale-up factors into constant velocity (CV) and constant bed volume per hour (CBVH) scale-up methods. Scale-up trials in bigger diameter (1.5 cm and 2.5 cm) columns with height to diameter ratio (H/D) =19 and &lt;19 were performed. The effects of changing flow velocity and H/D ratio due to the applied scale-up strategy were evaluated and compared with lab performance in terms of resolution vs. height equivalent to theoretical plate (HETP) relationship. The CBVH method was found to be an efficient method for the scale-up of the developed whey protein resolution system. Also an equation for the prediction of resolution in a scaled column on the basis of a HETP-resolution correlation is presented. It is useful for the prediction of either resolution or bed height in scaled column of WPC or similar biomolecular purification systems. <![CDATA[LIQUID-LIQUID EQUILIBRIA FOR SYSTEMS CONTAINING FATTY ACID ETHYL ESTERS, ETHANOL AND GLYCEROL AT 333.15 AND 343.15 K: EXPERIMENTAL DATA, THERMODYNAMIC AND ARTIFICIAL NEURAL NETWORK MODELING]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322018000200819&lng=en&nrm=iso&tlng=en Abstract In this study, the liquid-liquid equilibrium (LLE) data of systems containing ethyl linoleate/oleate/palmitate/laurate, ethanol and glycerol at temperatures ranging from 323.15 to 353.15 K were used to evaluate the performance of the NRTL, UNIFAC, Cubic-Plus-Association Equation of State (CPA EoS), and artificial neural network (ANN) models. The systems evaluated correspond to the most important components formed at the end of the ethanolysis reaction of soybean, palm and coconut oils. The temperature range selected is very important for heterogeneous catalysts, especially for high-pressure systems. The accuracy of the models was evaluated by average global deviation. UNIFAC, UNIFAC-LLE and CPA EoS models showed lower accuracy with deviations of 10.1, 8.01 and 5.95%, respectively. In spite of this predictive limitation, these models show high extrapolation capability for the description of LLE behavior when few experimental data are available in the literature. The ANN model shows the best agreement between experimental and predicted data with an average deviation of 1.12%. In this regard, ANN is offered in this work as an alternative to equations of state and activity coefficient models to be used in a more reliable and less cumbersome way for process simulators of biodiesel production and separation equipment design.