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Brazilian Journal of Chemical Engineering, Volume: 30, Número: 3, Publicado: 2013
  • Investigation of heat transfer processes involved liquid impingement jets: a review Reviews

    Molana, M.; Banooni, S.

    Resumo em Inglês:

    This review reports research on liquid impingement jets and the abilities, limitations and features of this method of heat transfer. Some available and important correlations for Nusselt number are collected here. Also we demonstrate the capability of nanofluids to be applied in heat transfer processes involved liquid impingement jets.
  • Kinetic study of the enzymatic hydrolysis of sugarcane bagasse Bioprocess Engineering

    Carvalho, M. L.; Sousa Jr., R.; Rodríguez-Zúñiga, U. F.; Suarez, C. A. G.; Rodrigues, D. S.; Giordano, R. C.; Giordano, R. L. C.

    Resumo em Inglês:

    This work presents a kinetic study of the enzymatic hydrolysis of three cellulosic substrates: filter paper (FP), used as a low recalcitrance substrate model; steam exploded sugarcane bagasse (SB); and weak acid pretreated SB (1:20 dry bagasse:H2SO4 solution 1% w/w), the last two delignified with 4% NaOH (w/w). The influence of substrate concentration was assessed in hydrolysis experiments in a shaker, using Accellerase® 1500, at pH 4.8, in 50 mM sodium citrate buffer. Cellulose loads (weight substrate/weight total) were changed between 0.5%-13% (for FP) and 0.99%-9.09% (for SB). For FP and low loads of steam exploded SB, it was possible to fit pseudo-homogeneous Michaelis-Menten models (with inhibition). For FP and higher loads of steam exploded SB, modified Michaelis-Menten models were fitted. Besides, it was observed that, after retuning of the model parameters, it is possible to apply a model fitted for one situation to a different case. Chrastil models were also fitted and they were the only feasible approach for the highly recalcitrant acid-treated SB.
  • Utilization of orange bagasse and molokhia stalk for production of pectinase enzyme Bioprocess Engineering

    Ahmed, S. A.; Mostafa, F. A.

    Resumo em Inglês:

    Studies were conducted on the production and extraction of exo-polygalacturonase (PG) in solid-state fermentation (SSF) using orange bagasse (Ob) and molokhia stalks (Ms) as a new solid support by Penicillium pinophlilum Hedg 3503 NRRL. The parameters affecting PG production under SSF were optimized. The maximum PG activity of ~ 3270 U/ g dry solid substrate was obtained from P. pinophlilum Hedg 3503 NRRL grown for 7 days on Ob and Ms in the ratio 1:3 (w/w), moistened with distilled water at 68.2% initial moisture content. Highest enzyme titers occurred in SSF without added nutrients, indicating nutrient sufficiency of the Ob and MS mixture to sustain growth and a high level of pectic substances which induced PG production. The extraction of PG from the fermented biomass was optimized. Among the various solvents tested, the maximum level of enzyme activity was achieved when acetate buffer (0.05 M; pH 5.0) was used. The optimum volume of buffer was 50 mL, an extraction time of 60 min was sufficient to extract most enzyme, which yielded 3269.6 U/ g dry solid substrate of enzyme activity. Repeated washes under the optimum conditions showed that most of the enzyme (about 98%) was recovered in three repeated extractions. Moreover, 68.9% of total activity was achieved in the first wash.
  • Evaluation of the microbial diversity of denitrifying bacteria in batch reactor Bioprocess Engineering

    Maintinguer, S. I.; Sakamoto, I. K.; Adorno, M. A. T.; Varesche, M. B. A.

    Resumo em Inglês:

    Microbial communities in an industrial activated sludge plant may contribute to the denitrification process, but the information on the microorganisms present in denitrifying reactors is still scarce. Removal of inorganic nitrogen compounds can be accomplished by the addition of carbon sources to the biological process of denitrification. Ethanol is an economically viable alternative as a carbon source in tropical countries like Brazil, with large-scale production from sugarcane. This paper reports the successful aplication of activated sludge with nitrate and ethanol in a batch anaerobic reactor. The operation lasted 61.5 h with total consumption of nitrate in 42.5 h, nitrite generation (2.0 mg/L) and ethanol consumption (830.0 mg/L) in 23.5 h. Denitrifying cell counts by the most probable number at the start of the operation were lower than at the end, confirming the ability of the inoculum from activated sludge for the denitrification process. The samples from cell counts were identified as Acidovorax sp., Acinetobacter sp., Comamonas sp. and uncultured bacteria. Therefore, these species may be involved in nitrate reduction and ethanol consumption in the batch reactor.
  • Enzymatic hydrolysis optimization of sweet potato (Ipomoea batatas) peel using a statistical approach Bioprocess Engineering

    Betiku, E.; Akindolani, O. O.; Ismaila, A. R.

    Resumo em Inglês:

    In this work, two-step enzymatic hydrolysis of sweet potato peel was optimized. The effects of time, enzyme dose and temperature on glucose concentration were investigated. The Box-Behnken design was applied and a total of 17 experimental runs were generated for each step. For the liquefaction step, an ANOVA test showed the quadratic model obtained to be significant (p < 0.05). The statistical model predicted the maximum glucose concentration to be 126.66 g/L at a temperature of 56.4 ºC, α-amylase dose 1% (v/v) and time 60 min. A quadratic model was also obtained for the saccharification step and the model was also significant (p < 0.05). The statistical model for the second step predicted the maximum glucose concentration to be 178.39 g/L, established at the temperature of 45 ºC, glucoamylase dose 1% (v/v) and time 60 min. The optimized liquefaction and saccharification conditions were validated with the actual glucose concentrations of 126.03 and 176.89 g/L, respectively.
  • Pineapple fruit bromelain recovery using recyclable functionalized ordered mesoporous silica synthesized from sugarcane leaf ash Bioprocess Engineering

    Arumugam, A.; Ponnusami, V.

    Resumo em Inglês:

    Bromelain, a protease enzyme found in Ananas comosus (Pineapple), was recovered from the fruit juice by adsorption using recyclable functionalized Santa Barbara Acid-15 (SBA-15) synthesized from sugarcane leaf ash. In this work, highly ordered mesoporous silica was synthesized from sugarcane leaf ash by a template-assisted method. It was successfully used as an adsorbent for the recovery of bromelain from pineapple fruit pulp. Amine-functionalized mesoporous silica exhibited a recovery efficiency of 97.89% and a 6.2-fold purification. It was also established that the adsorbent could be easily regenerated by adjusting the pH. In this study, the adsorbent was reused for three cycles without noticeable loss in recovery efficiency. Thus, adsroption using functionalized SBA-15 appears to be a promising alternate separation technique for the recovery of fruit bromelain.
  • Laboratory apparatus to evaluate microalgae production Bioprocess Engineering

    Gris, L. R. S.; Paim, A. C.; Farenzena, M.; Trierweiler, J. O.

    Resumo em Inglês:

    The application of microalgae for energy purposes and CO2 biomitigation continues to present a number of challenges, including the optimization of culture conditions. The application of experimental designs for microalgae cultivation is difficult, since experiments involving such microorganisms generally last days or weeks. This work proposes a multipurpose laboratory apparatus for the optimization of microalgae experimental conditions that simultaneously enables the evaluation of variables such as temperature, irradiance, photoperiod and CO2 concentration in the aeration stream, as well as variables related to the concentration of culture media nutrients. A case study is also presented in which temperature, concentration of f/2 medium sodium nitrate and the effects of incident light intensity on Nannochloropsis oculata lipid content are evaluated. Experiments were carried out following central composite designs, in batch cultivation within an airlift photobioreactor apparatus. The best experimental result was obtained at 21 ºC, 119 mg/L NaNO3 and 137 µE.m-2.s-1, corresponding to 41.8% lipids and 211.9 mg.L-1 final lipid concentrations.
  • Influence of co-substrates in the anaerobic degradation of an anionic surfactant Environmental Engineering

    Okada, D. Y.; Esteves, A. S.; Delforno, T. P.; Hirasawa, J. S.; Duarte, I. C. S.; Varesche, M. B. A.

    Resumo em Inglês:

    The removal of linear alkylbenzene sulfonate (LAS) was evaluated in a UASB reactor using short-chain alcohols (ethanol and methanol) and complex co-substrate (yeast extract). Using only methanol and ethanol as co-substrates resulted in removal of LAS between 30 and 41%. At the end, addition of a complex substrate (yeast extract) increased the removal of LAS to 50%. During the assay, water supply aeration increased the volatile fatty acid of the effluent (70 mg HAc.L-1) and decreased the removal of LAS (from 40 to 30%). According to the fluorescence in situ hybridization (FISH) results, the amount of Archaea decreased due to water supply aeration (from 64 to 48%). Furthermore, addition of complex co-substrate increased the total anaerobic bacteria and methanogenic archaea content (three and four log units, respectively), which were estimated using the most probable number technique.
  • Inactivation of Bacillus atrophaeus spores in healthcare waste by uv light coupled with H2O2 Environmental Engineering

    Iannotti, M. T.; Pisani Jr., R.

    Resumo em Inglês:

    Healthcare waste inoculated with B. atropheaus spores was used to evaluate a treatment process using UV light in combination with H2O2. First, the influence of the waste mass on the spore inactivation fraction was investigated for a constant radiation exposure time of 10 min and power per unit mass of waste (44-237 W/kg). The degree of inactivation of the spores was then determined as a function of exposure time (5-30 min) and power per mass unit (67-178 W/kg) for a constant waste mass. The experimental results were adjusted according to four kinetic models. The Hom and power law models were the most appropriate for the description of the disinfection process. The maximum experimental inactivation fraction (95%) achieved was obtained with 178 W/kg irradiation for 30 min.
  • Las degradation in a fluidized bed reactor and phylogenetic characterization of the biofilm Environmental Engineering

    Oliveira, L. L.; Costa, R. B.; Sakamoto, I. K.; Duarte, I. C. S.; Silva, E. L.; Varesche, M. B. A.

    Resumo em Inglês:

    A fluidized bed reactor was used to study the degradation of the surfactant linear alkylbenzene sulfonate (LAS). The reactor was inoculated with anaerobic sludge and was fed with a synthetic substrate supplemented with LAS in increasing concentrations (8.2 to 45.8 mg l-1). The removal efficiency of 93% was obtained after 270 days of operation. Subsequently, 16S rRNA gene sequencing and phylogenetic analysis of the sample at the last stage of the reactor operation recovered 105 clones belonging to the domain Bacteria. These clones represented a variety of phyla with significant homology to Bacteroidetes (40%), Proteobacteria (42%), Verrucomicrobia (4%), Acidobacteria (3%), Firmicutes (2%), and Gemmatimonadetes (1%). A small fraction of the clones (8%) was not related to any phylum. Such phyla variety indicated the role of microbial consortia in degrading the surfactant LAS.
  • Physical and physicochemical evaluation of different brands of traditional, low calorie and sugar-free guava preserves Fluid Dynamics; Heat And Mass Transfer; And Other Topics

    Pereira, P. A. P.; Souza, V. R.; Carneiro, J. D. S.; Borges, S. V.; Ferreira, L. O.; Queiroz, F.

    Resumo em Inglês:

    The aim of this study was to evaluate the physical and physicochemical properties of different brands of traditional (A, B and E), low calorie (C) and sugar-free (D) guava preserves. The results of these analysis indicated that there are differences in the physical and physicochemical properties of the different brands studied, and the partial and/or total exclusion of sugar from guava alters its physical and physicochemical properties, making the product redder; even added body and sweetening agents are incapable of conferring properties similar to those of conventional products. Regarding the relaxation test, the Maxwell model was the best for sample discrimination. The results also showed that the samples have a traditional standardization and that the sample labeled "low calorie" has a tendency to exhibit a composition similar to the conventional sample, which is evidence that brand (C) cannot be considered to be low calorie.
  • Hydrodynamics and oxygen mass transfer characteristics of petroleum based micro-emulsions in a packed bed split-cylinder airlift reactor Fluid Dynamics; Heat And Mass Transfer; And Other Topics

    Moraveji, M. Keshavarz; Mohsenzadeh, E.; Fakhari, M. Ebrahimi; Davarnejad, R.

    Resumo em Inglês:

    The effects of aeration velocity and liquid properties on the pertinent hydrodynamic and mass transfer parameters in a split-cylinder airlift reactor (with and without packing) were examined. Four different oil-in-water micro-emulsion systems containing kerosene, heavy naphtha, light naphtha and diesel as the oil at the concentration of 7% (v/v) were used in the experiments and the results were compared with pure water. The experimental results showed that the gas (air) hold-up and the volumetric gas-liquid oxygen transfer coefficient values for the micro-emulsion systems were usually greater than those of pure water. The packing installation increased the overall gas-liquid volumetric mass transfer coefficient by increasing the flow turbulence and Reynolds number, compared to the unpacked column. The packing increased the gas hold-up and decreased the bubble size and liquid circulation velocity. Furthermore, two empirical correlations were developed to predict the overall gas hold-up and volumetric oxygen transfer coefficient. A good agreement was observed between the experimental and correlated data.
  • Mass transfer of SO2 absorption with an instantaneous chemical reaction in a bubble column Fluid Dynamics; Heat And Mass Transfer; And Other Topics

    Li, Xiaolei; Zhu, Chunying; Lu, Sumin; Ma, Youguang

    Resumo em Inglês:

    Gas absorption accompanied by an instantaneous irreversible chemical reaction in bubble columns has been analyzed theoretically. A mass transfer model based on the Dankwerts surface-renewal model as well as the penetration theory for surface stretch proposed by Angelo et al. was developed, in which the effects of bulk motion and turbulence on mass transfer were taken into account. The analytical expressions for the time-average mass transfer coefficient and the enhancement factor have been obtained. The fast reactive absorption of SO2 from gas mixtures into aqueous NH4HCO3 solution was investigated experimentally in a bubble column reactor to validate the mass transfer model, and the results calculated by the present model agree well with the experimental results.
  • An experimental simulation model for coated paper drying Fluid Dynamics; Heat And Mass Transfer; And Other Topics

    Hallajisani, A.; Shahbeig, H.; Hashemi, S. J.; Douglas, W. J. Murray

    Resumo em Inglês:

    Due to the lack of information regarding the phenomena of mass, heat, and momentum transfer in coated paper drying, substantial research work still needs to be done. A simulation model for coated paper drying is introduced which integrates heat and mass transfer mechanisms. In the model, the coated paper was assumed to have 3 layers (coated layer, wet and dry layers of the base paper), in which the thickness of each layer is a function of drying time and condition. The thickness of the wet layer of the base paper was considered to be a function of water permeability rate that in turn is a function of the moisture diffusion coefficient, time and drying rate. Movement of vapor resulting from evaporation in the middle layer was assumed to be a combination of laminar bulk flow and molecular diffusion. Radiation absorption was used as a diminishing exponential model, which depends on moisture content. Hot air and super heated vapor were used as drying fluids. Functional variables were temperature, drying fluid velocity and delay time. To verify the simulation results two compositions were applied for the coating suspension. The simulation results matched well with experimental outcomes.
  • Influence of reaction operation conditions on the final properties of high impact polystyrene (hips) Kinetics And Catalysis; Reaction Enginneering; And Materials Science

    Cunha, F. R.; Costa, J. M.; Nele, M.; Folly, R. O. M.; Souza Jr., M. B.; Pinto, J. C.

    Resumo em Inglês:

    The main objective of the present work is to analyze the influence of some important operational reaction parameters (agitation speed, polybutadiene - PB - content and initiator concentration) on the final properties of High Impact Polystyrene (HIPS) produced in bulk. Variable effects are analyzed both qualitatively and quantitatively with the help of a fractional factorial design. Physical, chemical and mechanical properties were evaluated through measurement of the weight-average molecular weight (Mw), polydispersity (PD), volume-average diameter of PB particles (D(4,3)) and impact strength (Izod). It was found that PD and D(4,3) depend strongly on the initiator concentration, rubber concentration and agitation speed; Mw depends on initiator and rubber concentrations; and Izod depends on the rubber concentration, PD and D(4,3) in the analyzed experimental range. As a consequence, it was shown that control of final polymer properties can be easily performed through proper manipulation of the analyzed operational variables.
  • Preparation, characterization and gas permeation study of PSf/MgO nanocomposite membrane Kinetics And Catalysis; Reaction Enginneering; And Materials Science

    Momeni, S. M.; Pakizeh, M.

    Resumo em Inglês:

    Nanocomposite membranes composed of polymer and inorganic nanoparticles are a novel method to enhance gas separation performance. In this study, membranes were fabricated from polysulfone (PSf) containing magnesium oxide (MgO) nanoparticles and gas permeation properties of the resulting membranes were investigated. Membranes were prepared by solution blending and phase inversion methods. Morphology of the membranes, void formations, MgO distribution and aggregates were observed by SEM analysis. Furthermore, thermal stability, residual solvent in the membrane film and structural ruination of membranes were analyzed by thermal gravimetric analysis (TGA). The effects of MgO nanoparticles on the glass transition temperature (Tg) of the prepared nanocomposites were studied by differential scanning calorimetry (DSC). The Tg of nanocomposite membranes increased with MgO loading. Fourier transform infrared (FTIR) spectra of nanocomposite membranes were analyzed to identify the variations of the bonds. The results obtained from gas permeation experiments with a constant pressure setup showed that adding MgO nanoparticles to the polymeric membrane structure increased the permeability of the membranes. At 30 wt% MgO loading, the CO2 permeability was enhanced from 25.75×10-16 to 47.12×10-16 mol.m/(m².s.Pa) and the CO2/CH4 selectivity decreased from 30.84 to 25.65 when compared with pure PSf. For H2, the permeability was enhanced from 44.05×10-16 to 67.3×10-16 mol.m/(m².s.Pa), whereas the H2/N2 selectivity decreased from 47.11 to 33.58.
  • Magnetohydrodynamic axisymmetric flow of a third-grade fluid between two porous disks Process Systems Engineering

    Shafiq, A.; Nawaz, M.; Hayat, T.; Alsaedi, A.

    Resumo em Inglês:

    This paper investigates magnetohydrodynamic axisymmetric flow of a third-grade fluid between two porous disks. The governing partial differential equations are transformed into ordinary differential equations by similarity transformations. The resulting non-linear problem is solved by a homotopy analysis method (HAM). The effects of dimensionless parameters on the radial and axial components of the velocity are illustrated through plots. The skin-friction coefficients at the upper and lower disks are tabulated for various values of the dimensionless physical parameters.
  • Boundary layer stagnation-point flow of a third grade fluid over an exponentially stretching sheet Process Systems Engineering

    Rehman, A.; Nadeem, S.; Malik, M. Y.

    Resumo em Inglês:

    In this paper, the mixed convection steady boundary layer stagnation point flow and heat transfer of a third grade fluid over an exponentially stretching sheet is investigated. Both the analytical and numerical solutions are carried out. The analytical solutions are obtained through the homotopy analysis method (HAM) while the numerical solutions are computed by using the Keller box method (K-b). Comparison of the HAM and Keller-box methods is also given. The effects of important physical parameters are presented through graphs and the salient features are discussed.
  • Flow of a Williamson fluid over a stretching sheet Process Systems Engineering

    Nadeem, S.; Hussain, S. T.; Lee, Changhoon

    Resumo em Inglês:

    In the present article, we have examined the two dimensional flow of Williamson fluid model over a stretching sheet. The governing equations of pseudoplastic Williamson fluid are modelled and then simplified by using similarity transformations and boundary layer approach. The reduced equations are then solved analytically with the help of homotopy analysis method. The physical features of the model are presented and discussed through graphs.
  • The effect of the introduction of an exit tube on the separation efficiency in a cyclone Process Systems Engineering

    Cernecky, J.; Plandorova, K.

    Resumo em Inglês:

    The paper shows the analysis of the effect of introduction of an exit tube into the cylindrical part of a cyclone on the flow velocity, pressure losses and, above all, the separation efficiency. We made measurements and carried out CFD simulations for three levels of the exit tube introduction. The ratios of the depth of the exit tube introduction to the cyclone diameter (Hp/D) were 0.4, 0.475 and 0.89 at three velocity settings of 8 m.s-1, 13 m.s-1 and 15 m.s-1. The Reynolds Stress Model (RSM), which was compatible with the experimental results, was used for numerical solutions. The efficiency of cyclone separation was explored on a sample of oak sawdust. The efficiency of cyclone separation increased with the geometric size of the particles, the inlet velocity and a deeper introduction of the exit tube.
  • Numerical aspects of direct quadrature-based moment methods for solving the population balance equation Process Systems Engineering

    Santos, F. P.; Lage, P. L. C.; Fontes, C. E.

    Resumo em Inglês:

    Direct-quadrature generalized moment based methods were analysed in terms of accuracy, computational cost and robustness for the solution of the population balance problems in the [0,∞) and [0,1] domains. The minimum condition number of the coefficient matrix of their linear system of equations was obtained by global optimization. An heuristic scaling rule from the literature was also evaluated. The results indicate that the methods based on Legendre generalized moments are the most robust for the finite domain problems, while the DQMoM formulation that solves for the abscissas and weights using the heuristic scaling rule is the best for the infinite domain problems.
  • Adsorption of remazol brilliant blue on an orange peel adsorbent Separation Processes

    Mafra, M. R.; Igarashi-Mafra, L.; Zuim, D. R.; Vasques, É. C.; Ferreira, M. A.

    Resumo em Português:

    A novel orange peel adsorbent developed from an agricultural waste material was characterised and utilised for the removal of Remazol Brilliant Blue from an artificial textile-dye effluent. The adsorption thermodynamics of this dye-adsorbent pair was studied in a series of equilibrium experiments. The time to reach equilibrium was 15 h for the concentration range of 30 mg L-1 to 250 mg L-1. The adsorption capacity decreased with increasing temperature, from 9.7 mg L-1 at 20 ºC to 5.0 mg L-1 at 60 ºC. Both the Langmuir and Freundlich isotherm models fitted the adsorption data quite reasonably. The thermodynamic analysis of dye adsorption onto the orange peel adsorbent indicated its endothermic and spontaneous nature. Thus, the application of orange peel adsorbent for the removal of dye from a synthetic textile effluent was successfully demonstrated.
  • Effect of drying conditions on the physical properties of impregnated orange peel Separation Processes

    Manjarres-Pinzon, K.; Cortes-Rodriguez, M.; Rodríguez-Sandoval, E.

    Resumo em Inglês:

    Orange peel represents approximately 30-40 g/100g of the fresh fruit weight and could be used to develop value-added products. Hence, this study aims to evaluate the effects of drying conditions on the physical properties of orange peel impregnated with sucrose solution. The response surface method (RSM) was used to optimize two parameters: drying temperature (35-55 ºC) and air flow rate (2-3 m/s). The measured responses used to determine the effect of dying process conditions were: moisture content. drying time. total soluble solids. color and hardness. The dried orange peels from the optimal process were subjected to a sensory test by 60 consumers. The optimum conditions for the drying of orange peels were determined to obtain minimum hardness, moisture content and drying time for a w values below 0.6. The optimum conditions were found to be a dying temperature of 52.3 ºC and air flow rate of 2.0 m/s. At this point, drying time, hardness and moisture content were found to be 20 h, 78.4 N and 7.6%, respectively. The sensory results showed that consumers aged over 30 years old accepted well the dried orange peel.
  • Influence of polyvinylpyrrolidone on the interaction between water and methanol Thermodynamics

    Guettari, M.; Gomati, R.

    Resumo em Inglês:

    The present work aims to determine the influence of a dissolved polymer, polyvinylpyrrolidone, on the interaction between water and methanol. First, the dynamic viscosities were measured for polymer solutions by a rotational concentric cylinder at 25 ºC and for the polymer concentration range from 0.1 to 0.6 g/dl. The results show a polynomial dependence of the viscosity on polymer concentration. On the hypothesis of a quasi-binary system, a pseudo Grumberg-Nissan constant, d'p, was introduced to quantify the interaction between unlike molecules in the presence of polymer. The interaction between unlike molecules due to the presence of the polymer was quantified by the deviation of the Grumberg-Nissan constant, δd'p= d p. Generally, this constant is negative which means that the interactions between water and methanol decrease in the presence of polyvinylpyrrolidone at 25 ºC. The presence of the polymer induces a perturbation of the dynamic equilibrium between free and complexed molecules
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