Scielo RSS <![CDATA[Brazilian Journal of Chemical Engineering]]> http://www.scielo.br/rss.php?pid=0104-663220170001&lang=en vol. 34 num. 1 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[BIOMASS PYROLYSIS KINETICS: A REVIEW OF MOLECULAR-SCALE MODELING CONTRIBUTIONS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100001&lng=en&nrm=iso&tlng=en Abstract Decades of classical research on pyrolysis of lignocellulosic biomass has not yet produced a generalized formalism for design and prediction of reactor performance. Plagued by the limitations of experimental techniques such as thermogravimetric analysis (TGA) and extremely fast heating rates and low residence times to achieve high conversion to useful liquid products, researchers are now turning to molecular modeling to gain insights. This contribution briefly summarizes prior reviews along the historical path towards kinetic modeling of biomass pyrolysis and focusses on the more recent work on molecular modeling and the associated experimental efforts to validate model predictions. Clearly a new era of molecular-scale modeling-driven inquiry is beginning to shape the research landscape and influence the description of how cellulose and associated hemicellulose and lignin depolymerize to form the many hundreds of potential products of pyrolysis. <![CDATA[VALIDATION OF THE SULFO-PHOSPHO-VANILLIN (SPV) METHOD FOR THE DETERMINATION OF LIPID CONTENT IN OLEAGINOUS MICROORGANISMS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100019&lng=en&nrm=iso&tlng=en Abstract A colorimetric sulfo-phospho-vanillin (SPV) method was used to validate a high throughput method for total lipids analysis in fresh and lyophilized oleaginous microorganisms. This method uses a small amount of biological material, does not require a lot of sample manipulation, can be automated, is reproducible and easy to implement. A 96-well microplate SPV assay allows one to determine quickly total lipids in lyophilized cells of oleaginous yeast and microalgae. The new assay method possesses many advantages compared to the others described in the literature: requires a small amount sample, less time (around 1 h) and less labor and does not require organic reagents like chloroform in the reaction. <![CDATA[SYNTHESIS, CHARACTERIZATION AND APPLICATION OF A POLYURETHANE-BASED SUPPORT FOR IMMOBILIZING MEMBRANE-BOUND LIPASE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100029&lng=en&nrm=iso&tlng=en Abstract This study conducted an assessment of polyurethane foams that were synthesized by one-shot process and used as a low-cost support to immobilize Mucor circinelloides URM 4182 whole-cells presenting high lipolytic activity. Polyols with different molecular weights (1100 to 6000 g mol-1) were applied to synthesize the polymer matrix, and the agitation speed effect was used for controlling the average pore size of the investigated polyurethane foams. The physical and mechanical properties of the polymers were evaluated by standard test methods, and their morphology was identified by Scanning Electron Microscopy. The immobilization procedure efficiency was assessed by quantifying the capability of the matrices to attach the cells and the catalytic activity of the biocatalysts in both aqueous (olive oil hydrolysis) and non-aqueous media (ethanolysis of babassu oil) under single and consecutive batch runs. Although all synthesized matrices were suitable to immobilize the whole cells with high catalytic performance, a better set of parameters was attained when the polyol ether with molecular weight of 6000 g mol-1 and 1100 g mol-1 was used. Both matrices yielded immobilized biocatalysts with high hydrolysis and transesterification activities, and exhibited a satisfactory operational stability with 96% and 81% retention of their initial hydrolytic and transesterification activities after three consecutive batch runs. <![CDATA[PREPARATION AND CHARACTERIZATION OF IMMOBILIZED SPORES WITH LACCASE ACTIVITY FROM <em>Bacillus pumilus</em> W3 ON DEAE-CELLULOSE AND THEIR APPLICATION IN DYE DECOLORIZATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100041&lng=en&nrm=iso&tlng=en Abstract In order to obtain a more stable and reusable immobilized spore laccase for dye decolorization, the spores from Bacillus pumilus W3 were immobilized on diethylaminoethyl cellulose (DEAE-cellulose). Free and immobilized spore laccase retained 34.38% and 46.11% of their initial activity, respectively, after 10 days incubation at pH 9.0. Their residual activity remained at 27.36% and 31.84% after 10 h incubation at 70 ºC. Immobilized spore laccase was more stable than free spore laccase in the presence of most organic solvents, metal ions and inhibitors. The tested dyes, including methyl green, methyl red and acid red 1, were removed 86.82%, 78.14% and 88.60%, respectively, by immobilized spore laccase after 24 h at 37 ºC, and 74.34% of initial decolorization activity after 7 cycles was retained when it decolorized acid red 1. These properties indicated that immobilized spore laccase may be useful in textile effluent treatment. <![CDATA[MACHINE LEARNING TECHNIQUES APPLIED TO LIGNOCELLULOSIC ETHANOL IN SIMULTANEOUS HYDROLYSIS AND FERMENTATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100053&lng=en&nrm=iso&tlng=en Abstract This paper investigates the use of machine learning (ML) techniques to study the effect of different process conditions on ethanol production from lignocellulosic sugarcane bagasse biomass using S. cerevisiae in a simultaneous hydrolysis and fermentation (SHF) process. The effects of temperature, enzyme concentration, biomass load, inoculum size and time were investigated using artificial neural networks, a C5.0 classification tree and random forest algorithms. The optimization of ethanol production was also evaluated. The results clearly depict that ML techniques can be used to evaluate the SHF (R2 between actual and model predictions higher than 0.90, absolute average deviation lower than 8.1% and RMSE lower than 0.80) and predict optimized conditions which are in close agreement with those found experimentally. Optimal conditions were found to be a temperature of 35 ºC, an SHF time of 36 h, enzymatic load of 99.8%, inoculum size of 29.5 g/L and bagasse concentration of 24.9%. The ethanol concentration and volumetric productivity for these conditions were 12.1 g/L and 0.336 g/L.h, respectively. <![CDATA[EVALUATION OF THE FLOCCULATION EFFICIENCY OF <em>Chlorella vulgaris</em> MEDIATED BY <em>Moringa oleifera</em> SEED UNDER DIFFERENT FORMS: FLOUR, SEED CAKE AND EXTRACTS OF FLOUR AND CAKE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100065&lng=en&nrm=iso&tlng=en Abstract Flocculation as a pre-separation method can help make production of biodiesel from microalgae economically feasible. In a previous study, Moringa oleifera seed flour (1 g.L-1) was shown to be a very efficient flocculant for Chlorella vulgaris, a microalga with high potential for biodiesel production. In this study, several aspects of C vulgaris flocculation mediated by Moringa were investigated in order to optimize the separation of this biomass. Flocculation efficiency was the same with seeds from different origins and lots. The stationary growth stage was best for harvesting C vulgaris cells to carry out flocculation efficiently (93%). The use of flour extracts and cake extracts generated the best cost-benefit ratio (flocculation efficiency from 78 to 97% with a saving in mass of seed of 75%). The highest efficiency was reached with extracts prepared with seawater and NaCl solutions which have high salt concentration. Reasonable stability of the extract allows its use for up to two weeks, provided it is kept at low temperature (4 ºC). <![CDATA[BIODEGRADATION OF PHENOL BY FREE AND IMMOBILIZED CELLS OF A NOVEL <em>Pseudomonas</em> sp. NBM11]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100075&lng=en&nrm=iso&tlng=en Abstract In the present study, a pure culture of bacterium (Pseudomonas sp. Strain NBM11) was isolated from the soil sample from a site contaminated with medical wastes and wastewater. The isolated strain can degrade up to 1000 mg/L of phenol completely. It was observed that temperature, pH and initial concentration of phenol play key roles in determining the rate of phenol degradation. The isolated strain exhibited the maximal degradation of the substrate within a range of pH 6.8 to 7.2 and an incubation temperature between 30 ºC and 32 ºC. It was found that by increasing the concentration of phenol, the lag phase gets extended due to the inhibitory nature of phenol. The kinetic parameters such as µmax (maximum specific growth rate), Ks (half-saturation coefficient) and Ki (substrate inhibition constant) were estimated as 0.184 1/h, 7.79 mg/L and 319.24 mg/L, respectively, by fitting the growth kinetics data to the Haldane model of substrate inhibition. The bacterial strain was immobilized in alginate beads and its phenol degradation efficiency was observed to increase many fold. The immobilized cells were found to be used efficiently for seven cycles consecutively without any decrease in their efficiency. <![CDATA[SONO-OXIDATIVE PRE-TREATMENT OF WASTE ACTIVATED SLUDGE BEFORE ANAEROBIC BIODEGRADATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100085&lng=en&nrm=iso&tlng=en Abstract The effects of sonication, potassium ferrate (K2FeO4) oxidation and their simultaneous combination (called "sono-oxidative pre-treatment") on chemical properties and anaerobic digestion of waste activated sludge (WAS) were investigated and compared comprehensively. Based on chemical parameters, the optimum operating conditions were found to be 0.3 g K2FeO4/g total solids (TS) dosage for 2-h individual K2FeO4 oxidation, 0.50 W/mL ultrasonic power density for 10-min individual sonication and, lastly, the combination of 2.5-min sonication at 0.75 W/mL ultrasonic power density with 2-h chemical oxidation at 0.3 g K2FeO4/g TS dosage for sono-oxidative pre-treatment. The disintegration efficiencies of these methods under the optimized conditions were in the following descending order: 37.8% for sono-oxidative pre-treatment &gt; 26.3% for sonication &gt; 13.1% for K2FeO4 oxidation. The influences of these methods on anaerobic biodegradability were tested with the biochemical methane potential assay. It was seen that the cumulative methane production increased by 9.2% in the K2FeO4 oxidation reactor, 15.8% in the sonicated reactor and 18.6% in the reactor with sono-oxidative pre-treatment, compared to the control (untreated) reactor. <![CDATA[NANOFILTRATION AND REVERSE OSMOSIS APPLIED TO GOLD MINING EFFLUENT TREATMENT AND REUSE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100093&lng=en&nrm=iso&tlng=en Abstract Gold mining and ore processing are activities of great economic importance. However, they are related to generation of extremely polluted effluents containing high concentrations of heavy metals and low pH. This study aims to evaluate the optimal conditions for gold mining effluent treatment by crossflow membrane filtration regarding the following variables: nanofiltration (NF) and reverse osmosis (RO) membrane types, feed pH and permeate recovery rate. It was observed that retention efficiencies of NF90 were similar to those of RO membranes though permeate fluxes obtained were 7-fold higher. The optimum pH value was found to be 5.0, which resulted in higher permeate flux and lower fouling formation. At a recovery rate above 40% there was a significant decrease in permeate quality, so this was chosen as the maximum recovery rate for the proposed system. We conclude that NF is a suitable treatment for gold mining effluent at an estimated cost of US$ 0.83/m3. <![CDATA[A COMBINED ELECTROCOAGULATION-ELECTROOXIDATION TREATMENT FOR DAIRY WASTEWATER]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100109&lng=en&nrm=iso&tlng=en Abstract Dairy industry effluent is characterized by high chemical oxygen demand (COD) and other pollution load. This study addresses the elimination of organic compounds in dairy wastewater using electrocoagulation (EC), electrooxidation (EO) and a synergistic combination of EC and EO. The removal of COD, color and turbidity was investigated at various current intensities by using different electrodes and at various electrolysis times. Results show that EC is a relatively quick process (6 min), which is very effective in removing colloidal and suspended particles, as seen in changes in turbidity and color, but it is effective to eliminate only half of the COD. However, EO reduces 40% of COD in a practical time of about 30 min. To improve the removal of COD we proceeded to combine the two processes. Thus, the coupled process eliminates 60% of COD in a practical amount of time (21 min), removes the colloidal and suspended particles and eliminates color, turbidity, phosphorus, K+ and NTK. The use of the seed toxicity test allows evaluating the quality and effectiveness of the studied effluent treatment system. Seed irrigated with raw waste or treated dairy effluent show no phytotoxicity. <![CDATA[BIOLEACHING OF METALS FROM A SPENT DIESEL HYDRODESULFURIZATION CATALYST EMPLOYING <em>Acidithiobacillus thiooxidans</em> FG-01]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100119&lng=en&nrm=iso&tlng=en Abstract This study evaluates the recovery of heavy metals employing a spent catalyst from the hydrodesulfurization (HDS) of diesel, with no chemical, thermal or physical pretreatment, using the bacterial strain Acidithiobacillus thiooxidans FG-01. Direct and indirect bioleaching tests were carried out in Erlenmeyer flasks (500 mL). The influence of the pulp density and supplementation with elemental sulfur on the bioleaching were also investigated. The spent catalyst contained organochlorines, petroleum hydrocarbons and heavy metals in its composition. The best recovery results (26% Al, 26% V and 39% Mo) were achieved in the two-stage (indirect) bioprocess, with a pulp density of 50 g/L. It was not possible to recover Co, Cu and Ni (&lt; 5%) under any of the conditions tested. The bacterial strain A. thiooxidans FG-01 was found to be a promising candidate for the recovery of Al, V and Mo using the crude spent HDS catalyst. <![CDATA[USE OF A GRIFFITH TUBE TO EVALUATE THE ANAEROBIC SLUDGE SEDIMENTATION IN A UASB REACTOR TREATING AN EFFLUENT WITH LONG-CHAIN FATTY ACIDS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100131&lng=en&nrm=iso&tlng=en Abstract This paper proposes to study the sedimentation characteristics of anaerobic sludge, by determining the settling velocity of sludge granules with the Griffith Tube. This is a simple, low-cost method, suitable for use in full-scale treatment plants. The settling characteristics of sludge from two laboratory-scale UASB reactors fed with saccharose and different concentrations of sodium oleate and sodium stereate were evaluated. Addition of fatty acids caused a gradual destabilization of the system, affecting overall performance. The sedimentation profile changed after addition of fatty acids to the synthetic substrate, decreased sedimentation velocity and increased granule diameter. This behaviour was attributed to the adsorption of fatty acids onto the granules, modifying the diameter, shape and density of these bioparticles. <![CDATA[QUALITY, PERFORMANCE ANALYSIS, MASS TRANSFER PARAMETERS AND MODELING OF DRYING KINETICS OF SOYBEAN]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100143&lng=en&nrm=iso&tlng=en Abstract Different aspects of soybean drying such as energy and exergy analyses, quality, mass transfer parameters, and modeling of drying kinetics were investigated in a microwave dryer. Results showed that energy and exergy efficiency increased with increasing microwave power, while values of energy efficiency (33.70 to 66.0%) were higher than exergy efficiency (23.38 - 48.30%). Specific energy consumption and energy loss varied 4.93 to 9.11 MJ/kg water and 5.04 to 8.89 MJ/kg water, respectively. Approximately 8.94 to 20.07% of the total energy input is consumed by increasing of the product temperature. The values of improvement potential changed between 1.31- 5.35 MJ/kg water. Bulk density, degree of shrinkage and rehydration ratio varied from 726.6 to 762.8 kg/m3, 0.888 to 0.910, and 0.618 - 0.799, respectively. Parameters total color change (14.68 - 19. 89) and hue angle (88.07 to 91.73º) increased with increasing microwave power. Effective diffusivity and mass transfer coefficient varied from 1.99×10−9 to 12.25×10−9 m2/s and 2.71×10−6 to 19.98×10−6 m/s, respectively. The activation energy was found to be 4.98 W/g for a diffusion model and 5.33 W/g for a mass transfer model. Among the models, the Page model was found to best describe the drying behavior of soybean. <![CDATA[EXPERIMENTAL STUDY ON THE COLLABORATIVE DRAG REDUCTION PERFORMANCE OF A SURFACTANT SOLUTION IN GROOVED CHANNELS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100159&lng=en&nrm=iso&tlng=en Abstract Turbulence with a relatively larger vortex is obtained in drag-reducing surfactant solution, which provides an excellent condition for the application of small scale grooves. In this work, the coupling drag reduction performance of surfactant solution and grooves was experimentally investigated to explore the complementary possibility between their drag reduction mechanisms. The cationic surfactant cetyltrimethyl ammonium chloride (CTAC) mixed with the counterion salt sodium salicylate (NaSal) was experimented in smooth or grooved channel, respectively, at the mass concentrations of 50-150 ppm. It was found that the surfactant solutions gave more effective drag reduction in the grooved channel by the interaction between the "restriction effect" and "peak effect" of grooves. Moreover, the critical temperature and critical Reynolds number of the surfactant solution were smaller in the grooved channel, and the friction factor in the grooved channel increased much more rapidly than that in the smooth channel when Re is larger than a critical value. <![CDATA[EXPERIMENTAL APPROACH TO ASSESS EVAPORATIVE COOLING UNDER FORCED AIR FLOW]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100171&lng=en&nrm=iso&tlng=en Abstract Air blast is one of the most employed industrial chilling methods. It can be enhanced, i.e., increasing heat transfer and reducing cooling time, by superficial evaporative phenomena. This work reports a methodology, including experimental setup and mathematical modelling, to quantify the air chilling enhancement by wetting the surface of the object to be chilled. A spherical metal model was covered by a cotton tissue (wet or dry) and placed into a cold chamber. The effective heat transfer coefficient was determined at different temperature, air velocity, and relative humidity from time-temperature profiles into the sphere. Under the same air conditions, the effective coefficient between sphere and air was increased three-fold by moistening the cotton tissue on the sphere surface. Furthermore, comparing a dry and wet surface showed that evaporative cooling resulted in much shorter chilling times. The proposed approach was able to assess evaporative heat transfer by measuring only the time-temperature profile, and is suitable for industrial applications. <![CDATA[THE FORMATION BEHAVIOR OF A SINGLE BUBBLE IN POWER-LAW FLUIDS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100183&lng=en&nrm=iso&tlng=en Abstract The formation behavior of a single bubble in power-law fluids (carboxymethyl cellulose solution, CMC) and Newtonian fluids (glycerol solution) was experimentally investigated via a high-speed camera. The effects of liquid property, orifice diameter and gas flow rate on bubble volume and aspect ratio were observed. It was found that the formation time and detaching volume increased with the increase of fluid viscosity. The increase of bubble aspect ratio during the bubble formation process was complex, with main emphasis on the decrease in the initial stage and an increase in the final stage along with the shear thinning property variation. Nevertheless, the bubble detaching volume, instantaneous volume and formation time increased following the increase of orifice diameter and gas flow rate. On the contrary, the bubble aspect ratio decreased with the orifice diameter increase but increased with a higher gas flow rate. <![CDATA[DECHLORINATION OF ZINC OXIDE DUST DERIVED FROM ZINC LEACHING RESIDUE BY MICROWAVE ROASTING IN A ROTARY KILN]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100193&lng=en&nrm=iso&tlng=en Abstract The dechlorination efficiency of zinc oxide dust using microwave roasting was investigated capitalizing on the different microwave absorbing capacities of the compounds such as chlorine, lead, and zinc oxide. The associated dechlorination reactions were discussed in detail and the effect of all the influencing parameters such as the air flow rate, steam flow rate, the roasting temperature, roasting duration, and the mixing rate were assessed to identify the optimal conditions. The results indicated that a near 93% dechlorination of zinc oxide dust could be achieved, which would satisfy the requirements of the wet smelting electrolysis process. The optimal process parameters were identified to be an air flow of 300 L/h, a steam flow of 8 mL/min, a stirring speed of 60 rpm, a roasting temperature of 650 ºC, and a roasting duration of 60 min. Water vapor has an enhanced effect on dechlorination by microwave roasting. <![CDATA[PREPARATION OF ZEOLITE X COATINGS ON SODA-LIME TYPE GLASS PLATES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100203&lng=en&nrm=iso&tlng=en Abstract The dissolution of glass in highly alkaline reaction mixtures and the impact of this phenomenon on zeolite coating formation were investigated. Coating samples were prepared and characterized by X-ray diffraction (XRD), field emission gun scanning electron microscopy (FEGSEM) and thermogravimetry (TG). It was demonstrated that zeolite X coatings might be prepared on soda-lime glass. Glass dissolved to some degree, up to 2% of its original mass, in the reaction mixtures for the conditions investigated. This dissolution affected the zeolite synthesis taking place on the glass surface, resulting in phases different from those obtained on inert metal surfaces in some cases, especially for the use of reaction mixtures with relatively high Si/Al ratios. The percentage of dissolution of glass plates increased with their decreasing thickness, indicating a surface phenomenon for the dissolution. The stabilities of the coatings, which varied with the synthesis conditions, benefited from the addition of extra thin layers of polyacrylic acid. <![CDATA[MATHEMATICAL MODELING OF THE ELECTRIC CURRENT GENERATION IN A MICROBIAL FUEL CELL INOCULATED WITH MARINE SEDIMENT]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100211&lng=en&nrm=iso&tlng=en Abstract Microbial fuel cells (MFC) are electrochemical devices that utilize the ability of some microorganisms to oxidize organic matter and transfer electrons resulting from their metabolism to an insoluble acceptor. The goal of the present study was to model the kinetics of electrical current generation from an MFC inoculated with marine sediment. For this purpose, a differential equation system was used, including the Nernst-Monod relationship and Ohm's Law, to describe the microbial metabolism and the mechanism of extracellular electron transfer (EET), respectively. The experimental data obtained by cyclic voltammetry analysis were properly described by the model. It was concluded that marine microorganisms preferably use a direct mechanism of EET by means of nanowires to establish the electrochemical contact with the anode. The mathematical modeling could help understand MFC operation and, consequently, contribute to improving power generation from this source. <![CDATA[INVESTIGATING THE LONG-TERM STABILITY AND KINETICS OF SUPEROXIDE ION IN DIMETHYL SULFOXIDE CONTAINING IONIC LIQUIDS AND THE APPLICATION OF THIOPHENE DESTRUCTION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100227&lng=en&nrm=iso&tlng=en Abstract The long-term stability of superoxide ion (O2•−) with four ionic liquids (ILs), namely 1-(2-methoxyethyl)-1-methylpiperidinium tris(pentafluoroethyl)trifluorophosphate [MOEMPip][TPTP], 1-(3-methoxypropyl)-1-methylpiperidinium bis(trifluoromethylsulfonyl)imide [MOPMPip][TFSI], N-ethyl-N,N-dimethyl-2-methoxyethylammonium bis(trifluoromethylsulfonyl)imide [N112,1O2][TFSI], and ethyl-dimethyl-propylammonium bis(trifluoromethylsulfonyl)imide [EDMPAmm][TFSI], was studied for up to 24 h using two-second intervals. This was achieved by chemical generation of O2•− by dissolution of potassium superoxide salt in dimethyl sulfoxide and the subsequent addition of the IL. The decrease in the concentration of O2•− after the introduction of the IL was monitored using a UV-vis spectrophotometer. The ammonium-based ILs were found to be more stable than piperidinium-based ILs. To the best of our knowledge, this was the first time that O2•− stability with ILs has been monitored continuously for up to 24 h. This should provide a better insight into the stability and kinetics of O2•− for industrial applications and its role in energy-storage devices. The most appropriate IL as a medium was [EDMPAmm][TFSI], and O2•− generated in this IL was used to destroy nearly 90% of thiophene. <![CDATA[EFFECTS OF NANOPARTICLES AND SURFACTANT CHARGE GROUPS ON THE PROPERTIES OF VES GEL]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100241&lng=en&nrm=iso&tlng=en Abstract Application of viscoelastic surfactant (VES) fluids in hydraulic fracturing is still in the development stage, though shear thinning behavior and water solubility are the two important characteristics behind increasing interest in their use in fracturing jobs. Effects of ionic characteristics and the concentration of different surfactants on the rheological properties of VES fluid have been investigated in detail in the present study for a number of surfactant systems. Phase behavior of the system was studied and the gel region was identified. Effects of alkali on the viscosity, thermal stability, and miscibility (in water) of the developed gel were also investigated. Dynamic rheological study was carried out to determine the storage modulus and loss modulus. This study shows that mixed anionic-anionic system gives improved rheology compared to single anionic and mixed anionic-zwitterionic surfactant systems. <![CDATA[SPINNABILITY, MORPHOLOGY AND MECHANICAL PROPERTIES OF GELATINS WITH DIFFERENT BLOOM INDEX]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100253&lng=en&nrm=iso&tlng=en Abstract The influence of the concentration, viscosity, electrical conductivity and Bloom index of gelatin solutions on the electrospinning process and the fibrous membrane formed was evaluated. Electrospun membranes were produced at different concentrations for three Bloom values (90, 250 and 280); the solutions were evaluated in terms of viscosity and electrical conductivity and the fibrous membranes by SEM and tensile tests. Results indicate that the electrospinning was most successful when the solution viscosity was within the range of 300 to 700 mPa·s, regardless of the type of gelatin used in the investigated conditions. The average fiber diameter increased with the increased solution viscosity and the relationship between them was well described by a linear equation. With regard to the mechanical properties, GeB250 and GeB280 fibrous membranes showed elongation, on average, at least ten times higher than that of GeB90 membranes. <![CDATA[EVALUATION OF LIMESTONE IMPURITIES IN THE DESULFURIZATION PROCESS OF COAL COMBUSTION GAS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100263&lng=en&nrm=iso&tlng=en Abstract Limestones have been used to capture SO2 emitted during the combustion of coal for decades. However, due to the complexities of the variables involved in this process, many issues are still being studied. Some tests were performed in a fluidized bed reactor, which was used to evaluate the performance of the limestones in the bed for flue gas desulfurization, burning low sulfur coal. Metamorphic dolomitic limestones of low cost were evaluated considering the impurity level and need for beneficiation. They were characterized chemically, physically and microstructurally (X-ray fluorescence, X-ray diffraction, laser particle size analyzer, scanning electronic microscope). The data obtained were compared to a calcitic limestone of elevated purity and higher market value. The results showed little effect of the major impurities present in the dolomitic limestones in the calcination and desulfurization processes. Microcrystalline impurities showed a marked effect promoting grain sintering in calcination conditions of TGA/DTA tests in different atmospheres, as shown in SEM images. Dolomitic limestones generate more solid waste and capture less SO2 per kcal (a slightly decrease in the thermal efficiency of the reactor) compared to calcitic limestones. However, due to the lower cost, they were considered to be attractive for the FBC process (2 mg SO2/kcal at Ca/S=3). <![CDATA[CHEMICAL DEMULSIFICATION OF MODEL WATER-IN-OIL EMULSIONS WITH LOW WATER CONTENT BY MEANS OF IONIC LIQUIDS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100273&lng=en&nrm=iso&tlng=en Abstract The demulsification of model water-in-oil (w/o) emulsions containing 1% wt. water by [Omim][PF6] and Aliquat® 336 ionic liquids (IL) as demulsifiers was investigated in batch mode at different temperatures (30, 45 and 60 °C) and demulsifier concentrations (2.5×10‒3, 1.2×10‒2 and 2.9×10‒2 mol L‒1). The model oil is a mixture n-heptane/toluene (70/30% wt.) with 1% wt. of Span® 83 as a surfactant. Experimental results showed that the main differences in demulsification dynamics between systems containing IL and blank (i.e., in the absence of demulsifier) are detected at 30 °C and for short demulsification times (t≤4 h). In particular, the demulsification efficiency is 8, 21 and 74% for the blank sample, [Omim][PF6] and Aliquat® 336 tested under the more concentrated IL condition, respectively. The superior demulsification performances of Aliquat® 336 with respect to [Omim][PF6] were related to the greater molecular weight and more hydrophobic character of its cation, likely able to induce a faster desorption of the surfactant at the w/o interface and consequently promoting water droplet coalescence. Moreover, the kinetic demulsification data were successfully interpreted by an empirical pseudo-first order model. In general, the obtained outcomes encourage future research efforts in the use of ionic liquids for the removal of low water fractions from w/o emulsions. <![CDATA[AN ALTERNATIVE ROUTE TO PRODUCE STANDARDS FOR GEL PERMEATION CHROMATOGRAPHY USING NITROXIDE MEDIATED POLYMERIZATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100283&lng=en&nrm=iso&tlng=en Abstract All over the world standards for Gel Permeation Chromatography (GPC) are produced using ionic polymerization. Standards are commercialized in a broad range of molecular weight and their dispersity (Ð) must be lower than 1.1. This work proposes the synthesis of polystyrene standards using Nitroxide Mediated Polymerization (NMP), an alternative technique to produce controlled polymers that is much more robust when compared to ionic polymerization. Standards with different ranges of molecular weights were obtained, all of them with very narrow molecular weight distribution (MWD) and dispersity (Ð) lower than 1.10. In order to do that, several combinations of different initiators were tested. Advanced GPC Triple Detector was used to obtain important properties, such as absolute number and weight average molecular weights, dispersity and intrinsic viscosity. The analytical method used in the characterization of the samples was in-house validated in terms of linearity, accuracy, precision, repeatability and robustness. The validation study demonstrated the quality of the measurements and ensured that the information obtained for a given analyte by the GPC technique is reliable. <![CDATA[SYNTHESIS OF 2,6-DIMETHYLNAPHTHALENE OVER SAPO-11, SAPO-5 AND MORDENITE MOLECULAR SIEVES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100295&lng=en&nrm=iso&tlng=en Abstract Shape-selective methylation of naphthalene over SAPO-11, SAPO-5 and mordenite molecular sieves were carried out in a fixed-bed flow reactor under atmospheric pressure. Methanol and mesitylene were used as methylation and solvent agents. The experiment results showed that SAPO-11 exhibited higher stability, higher selectivity of 2,6-dimethylnaphthalene (2,6-DMN) and higher 2,6-/2,7-DMN ratio than SAPO-5 and mordenite molecular sieves. The catalytic performances for the methylation of naphthalene were mainly related to the pore structure of the catalysts. The comparison of the spent SAPO- 11 with fresh SAPO-11 suggested that structure collapse of the SAPO-11 by dealumination was occurred during the methylation of naphthalene with methanol, which may have been caused by high temperature steam from water produced in the reaction or by high temperature methanol vapor. <![CDATA[NUMERICAL RESEARCH ON THE THREE-DIMENSIONAL FIBER ORIENTATION DISTRIBUTION IN PLANAR SUSPENSION FLOWS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100307&lng=en&nrm=iso&tlng=en Abstract To describe flow-induced fiber orientation, the Fokker-Planck equation is widely applied in the processing of composites and fiber suspensions. The analytical solution only exists when the Péclet number is infinite. So developing a numerical method covering a full range of Péclet number is of great significance. To accurately solve the Fokker-Planck equation, a numerical scheme based on the finite volume method is developed. Using spherical symmetry, the boundary is discretized and formulated into a cyclic tridiagonal matrix which is further solved by the CTDMA algorithm. To examine its validity, benchmark tests over a wide range of Péclet number are performed in a simple shear flow. For Pe=∞, the results agree well with the analytical solutions. For the other Pe numbers, the results are compared to results available in the literature. The tests show that this algorithm is accurate, stable, and globally conservative. Furthermore, this algorithm can be extended and used to predict the three-dimensional orientation distribution of complex suspension flows. <![CDATA[CONTROL PROPOSAL FOR A HIGH PURITY COLUMN BASED ON THE SEPARATION OF VARIABLES BY THE INDEPENDENT COMPONENT ANALYSIS METHOD]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100317&lng=en&nrm=iso&tlng=en Abstract Many industries are complex when it comes to operation mode. In order to reduce the problems related to strong coupling in these processes, the search for the incorporation of artificial intelligence devices has shown an increasing trend in recent years. Due to this complexity and control in multivariable processes, diagnosis and fault monitoring in the processes have become increasingly difficult. Therefore, the application of these devices has achieved satisfactory results regarding the procedures performed with human operators. Independent Component Analysis (ICA) is a signal separation technique that is based on the use of higher order statistics to estimate each of the unknown sources, through observation of various mixtures generated from these sources. Although there are recent works on using the ICA in industrial processes, few studies have been made in cases involving distillation columns. This paper proposes a control strategy based on the ICA technique, which makes the control loops decoupled and hence the performance easier. Compared to the conventional method, the technique provided a great improvement in control performance. Control structures were implemented in Simulink/Matlab® in communication with a 1,2-dichloroethane (1,2-EDC) plant simulated in Aspen Plus DynamicsTM. <![CDATA[TITANATE NANOTUBES PRODUCED FROM MICROWAVE-ASSISTED HYDROTHERMAL SYNTHESIS: CHARACTERIZATION, ADSORPTION AND PHOTOCATALYTIC ACTIVITY]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100331&lng=en&nrm=iso&tlng=en Abstract A microwave-assisted hydrothermal (MAH) method was employed to synthesize TiO2 nanotubes (TNTs) and these were compared to the conventional hydrothermal (CH) method. The nanotubes were characterized for their crystallinity, morphology, surface area and photocatalytic activity. The TiO2 P25 was used for comparison purposes and efficiently degraded both dyes. However, methylene blue was adsorbed on the nanotube surfaces, which can be attributed to the electrostatic interaction between the cationic methylene blue and the negatively charged TNT surface. On the other hand, all nanotubes had a photocatalytic performance with methyl orange (anionic dye). Additional degradation was observed for nanotubes synthesized via the MAH method at 150 °C. This can be directly related to their larger surface area. Adsorption mechanisms of TNTs were also discussed by applying the Langmuir and Freundlich isotherm. The results show an efficient dye wastewater treatment through the application of TNT photocatalyst. <![CDATA[EXPERIMENTAL DATA, THERMODYNAMIC MODELING AND SENSITIVITY ANALYSES FOR THE PURIFICATION STEPS OF ETHYL BIODIESEL FROM FODDER RADISH OIL PRODUCTION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100341&lng=en&nrm=iso&tlng=en Abstract The goals of this work were to present original liquid-liquid equilibrium data of the system containing glycerol + ethanol + ethyl biodiesel from fodder radish oil, including the individual distribution of each ethyl ester; to adjust binary parameters of the NRTL; to compare NRTL and UNIFAC-Dortmund in the LLE representation of the system containing glycerol; to simulate different mixer/settler flowsheets for biodiesel purification, evaluating the ratio water/biodiesel used. In thermodynamic modeling, the deviations between experimental data and calculated values were 0.97% and 3.6%, respectively, using NRTL and UNIFAC-Dortmund. After transesterification, with 3 moles of excess ethanol, removal of this component until a content equal to 0.08 before an ideal settling step allows a glycerol content lower than 0.02% in the ester-rich phase. Removal of ethanol, glycerol and water from biodiesel can be performed with countercurrent mixer/settler, using 0.27% of water in relation to the ester amount in the feed stream. <![CDATA[MODELING OF THE SOLVENT EXTRACTION EQUILIBRIUM OF URANIUM (VI) SULFATE WITH ALAMINE 336]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100355&lng=en&nrm=iso&tlng=en Abstract The present study investigated the solvent extraction of uranium from sulfate acid solutions using Alamine 336 as an extractant dissolved in commercial kerosene Exxsol D-100 and 5% v/v of tridecanol as a modifying agent at room temperature (25±2) ºC and an aqueous/organic volumetric ratio of unity. Experiments were carried out at typical concentration levels like those used at the uranium plant of INB (Indústrias Nucleares do Brasil), Brazil. Data fitting using the slope analysis method revealed that uranium is extracted by Alamine 336 as UO2SO4 and UO2(SO4)22- species, forming (R3NH+)2UO2(SO4)22- in the organic phase; the extraction of the species UO2(SO4)34- seems improbable for the operating conditions investigated. The extraction of uranium is significantly reduced when the concentrations of sulfate and chloride ions in the aqueous phase are increased. <![CDATA[Solubility of 1-Adamantanamine hydrochloride in Six Pure Solvents between 283.15 K and 333.15 K]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0104-66322017000100363&lng=en&nrm=iso&tlng=en Abstract The solubility of 1-adamantanamine hydrochloride (1-AH) in ethanol, acetic acid, distilled water, N -methylpyrrolidone (NMP), N,N -dimethylformamide (DMF) and dimethylacetamide (DMAC) between 283.15 K and 333.15 K was measured using a laser monitoring observation technique. Results of these measurements were correlated with the NRTL equation and a semi-empirical equation. For six solvents studied, the data are well fitted with the two equations, which can be used as a useful model in the production process of 1-AH.