Resumo em Inglês:

Abstract The production of protease from Bacillus licheniformis LBA 46 was studied in a 6 L reactor using the experimental design tool. The higher protease production was obtained in the exponential phase of growth reaching maximum activity (~3,000 U/mL) after 48 h of fermentation at 30 ºC and 300 rpm in a culture medium made of agroindustrial by-products. In the thermostability study, the semi-purified enzyme retained about 78% of the initial activity after 120 min at 50 ºC. The protease was purified 3.33 times by ammonium sulfate precipitation and DEAE-Sepharose column chromatography and had a molecular mass estimated at 40 kDa by SDS-PAGE. The purified protease showed optimum activity at 50 and 60 ºC, optimal activity in pH 8.5 and stability in the range between pH 5-10 after 24 h of incubation at 4 ºC, presenting more than 86% of the initial activity.

Resumo em Inglês:

Abstract Biological flocculants are advantageous due to their biodegradability and safety to living beings. In this work, four bacterial strains, isolated from sugarcane cropped soil (Bacillus megaterium LBPMA-APFSG3Isox and B. toyonensis LBPMA-ACOPR1.Isox) and sludge of an agroindustrial effluent (B. pumilus LBPMA-BLD07 and B. thuringiensis LBPMA-EFIII), were studied. It was found that all of them secreted bioflocculants, at 37 ± 1 °C, with no pH changes over time and the flocculant activity increased during the time course of incubation. These results stimulated the optimization of the culture conditions to improve flocculation rates, such as the pH, nitrogen sources and carbon. For B. toyonensis LBPMA-ACOPR1.Isox and B. thuringiensis LBPMA-EFIII, the best pH for the bioflocculant production was 5.0. Sucrose and maltose were the best sources of carbon, while urea was the preferred source of nitrogen for two of the tested isolates (B. pumilus LBPMA-BLD07 and B. toyonensis LBPMA-ACOPR1.Isox), followed by (NH4)2SO4 (B. megaterium LBPMA-APFSG3Isox) and peptone (B. thuringiensis LBPMA-EFIII). The FTIR-ATR spectra of each extracted material responsible for the flocculant activities of the strains displayed carboxyl, hydroxyl and methoxy functional groups characteristic of polysaccharides.

Resumo em Inglês:

Abstract CO2 biofixation of the microalgae Chlorella sp. for different CO2 concentrations and gas flow rates in a bubble column reactor has been investigated in this study. Microalgae were cultivated under different CO2 concentrations (at 1.75% and 9.45% v/v) and gas flow rates (at 30, 50 and 70 ml/min). The maximum specific growth rate of Chlorella sp. was obtained for the CO2 concentration of 1.75 % and the gas flow rate of 50 mL/min. The highest biomass productivity rate (at 0.17 g L-1 day-1) was for a sample with 1.75 % CO2 at a flow rate of 70 ml/min. Moreover, the results have shown that the specific growth rate and CO2 biofixation have a direct relation with culturing of Chlorella sp. Also, limiting CO2 supplementation noticeably decreased biomass concentration. Therefore, the results have shown that a high flow rate and low concentration of CO2 might promote a decrease in CO2 fixation efficiency by Chlorella sp.

Resumo em Inglês:

Abstract Protein hydrolysis can improve food’s nutritional, techno-functional and biological properties, which can increase the possibilities of application in industry. The objective of this research article was to study the effect of lipids on the enzymatic kinetics of red tilapia viscera (RTV) hydrolysis with subtilisin Carlsberg. The RTV were hydrolyzed in an enzyme/substrate ratio of 0.153 (U/g), at 53° C, at a pH of 9.5, initial concentrations of lipids of 1, 19 and 50 g/L, and different initial substrate concentrations for each initial lipid concentration. To explain the lipid action mechanism, we evaluated a Michaelis-Menten model and another semi-physical model based on kinetic expressions and mass balances. Additionally, a molecular docking analysis was performed between subtilisin Carlsberg and the main fatty acid in RTV (palmitic acid). For both models, the results suggest a strong competitive inhibition by lipids, with an inhibition constant of 2.36 and 3.01 g/L for the first and second models, respectively. On the other hand, docking suggested that palmitic acid could form van der Waals interactions and hydrogen bonds with the residues of the active site of subtilisin Carlsberg and occupy part of the substrate binding site, thus acting as an effective competitive inhibitor.

Resumo em Inglês:

Abstract Fructooligosaccharides (FOS) are mainly produced by microbial fructosyltransferases (FTase, E.C.2.4.1.9), and Aspergillus oryzae IPT-301 has shown high fructosyl transferring and low hydrolytic activities, which leads to high FOS production yields, but the main operating parameters for its best performance have been scarcely studied. Thus, this work aimed to evaluate the cellular growth, production and characterization of mycelial and extracellular FTases by Aspergillus oryzae IPT-301. Experimental design showed that the extracellular FTase performance was optimized (high transfructosylation activity and low hydrolytic activity) for reaction pH 5.5 - 6.75 and temperature of 45-50 °C and was fitted by the Michaelis-Menten model, while the mycelial FTase showed better performance at pH below 6.5 and temperature above 46 °C and was better fitted by the Hill model. The results obtained showed that the fungus represents a promising source for FOS production on a laboratorial scale.

Resumo em Inglês:

Abstract The aim of this investigation was to study the degradation of tributyl phosphate (TBP) in aqueous solution by heterogeneous photocatalysis (UV-C/TiO2). To perform the investigation, aqueous solutions containing the contaminant were exposed to UV radiation in the absence or presence of TiO2 in suspension or supported on a Fe-Cr metal alloy plate. TBP analyses before and after the treatment were performed by Ultra-Performance Liquid Chromatography (UPLC) in order to quantify the contaminant degradation. The results showed that the TiO2 photocatalytic system was able to remove TBP from the solution and the formation of some by-products was observed. TiO2 photocatalytic systems were able to reduce acute toxicity in an Artemia Salina bioassay according to the increase in LC50 from 10.2 ± 0.5%(v/v) to 16.9 ± 0.6 %(v/v) for the immobilized system and to levels which were not possible to detect by the applied method any more for the suspension system.

Resumo em Inglês:

Abstract This study evaluated the biooxidation of pyrite contained in a Colombian coal (2.38 mm < particle size < 0.50 mm). The variables were cysteine concentration (0-600 mg/L) and culture type (pure Acidithiobacillus ferrooxidans (ATCC 23270) and a consortium of Acidithiobacillus thiooxidans (ATCC 15494) and Acidithiobacillus ferrooxidans). Pyrite oxidation for the assays without cysteine was 31.14% after 12 days. In the presence of pure A. ferrooxidans, oxidation increased by 8.18% in the assays containing 60 mg Cys/L. In contrast, the counterpart using the consortium exhibited a significant increase in redox potential, which improved oxidation by 28.44%. Since all the assays had a similar kaolinite removal (around 31.45%), and the experiments without cysteine did not show differences in behaviour, the A. thiooxidans-cysteine interactions might have been responsible for increasing Fe3+ regeneration, alleviating the toxic effect of Al3+ ion dissolution, thus improving pyrite oxidation. The consortium-cysteine-coal interactions contrasted with those proposed by other authors for A. ferrooxidans-cysteine-pure pyrite and A. thiooxidans-cysteine, indicating different metabolic pathways in the presence of inorganic and organic coal matrices. On the other hand, the biooxidation rate decreased for both cultures in the presence of 600 mg Cys/L, showing similar inhibition to that reported in the literature.

Resumo em Inglês:

Abstract Submerged Membranes Bioreactors (SMBR) are an established technology for wastewater treatment for water recovery and reuse. However, its routine application is still compromised by the high energy consumption to overcome the fouling effect. This study evaluated the effect of aluminum sulfate and cationic polymer in the orthophosphate removal and sludge filterability improvement in the mixed liquor of a SMBR pilot system. Parameters such as coagulant concentration, filtration time, extracellular polymeric substances (EPS) reduction and orthophosphate removal were evaluated by using a jar-test and a stirred cell. As results, aluminum sulfate and polymer additions improved the filtration index (FI30) from 25% to 32 %, for both chemicals. Time-to-filter (TTF) results evidenced a positive and significant correlation between aluminum sulfate dosage and colloidal EPS reduction.

Resumo em Inglês:

Abstract Structured catalysts were prepared, characterized and evaluated in NO3 - removal from drinking water. Different suspensions containing a previously optimized PdCu/5wt% ZrO2-Al2O3 powder catalyst (hereinafter PdCu/5ZAp) were prepared and deposited on cordierite monoliths by washcoating. The effect of suspension concentration, the particle size, the immersion number, the use of suspension stabilizer agent, and an alumina pre-coating on the coating adherence and catalytic performance were studied. All the prepared structured catalysts were active for the elimination of NO3 - and presented good selectivity to N2 (> 93%) in synthetic water samples. The catalyst performance was related to the amount of deposited catalyst. The highest activity and the best coating adherence were obtained with the structured catalyst prepared by a single immersion in a 14 wt% concentration suspension, which was obtained from the powder catalyst milled for 10 h and stabilized with colloidal alumina. This catalyst also showed good activity when it was reused for four cycles and when it was evaluated with real water samples.

Resumo em Inglês:

Abstract Thermophilic anaerobic digestion treatment of industrial wastewater generated at high temperatures can be used as an alternative for environmental pollution control and bioenergy production. Therefore, this study investigated thermophilic anaerobic reactors containing immobilized biomass (AnSBBR) to treat vinasse for methane production, in batch and fed-batch mode, in a three-step approach. In Step I (batch), the biomass was properly adapted to the thermophilic condition (55 °C) with a feed containing vinasse plus molasses as a co-substrate. In Step II (batch), the applied volumetric organic load (AVOL) was increased and resulted in a methane molar productivity of 304 molCH4.m-3.d-1 at an AVOL of 25.9 gCOD.L-1.d-1 and a yield of methane per removed organic matter near 331 NmL-CH4.gCOD-1. In Step III, a fed-batch strategy was employed at an AVOL of 25.1 gCOD.L-1.d-1 and achieved an optimum methane productivity of 352 molCH4.m-3.d-1 with COD and carbohydrate removal efficiencies of approximately 80 % and 90%, respectively. A kinetic model fitted to the experimental data allowed better understanding of the anaerobic metabolic reactions. Finally, the results obtained demonstrated that a thermophilic AnSBBR is an efficient technological alternative for methane production through vinasse digestion.

Resumo em Inglês:

Abstract Biological acid mine drainage treatment depends significantly on inoculum origin, pH, COD/sulfate ratio, and carbon source. In this study, the performance and microbial diversity of anaerobic batch reactors used for sulfate reduction was evaluated. A medium COD/sulfate ratio of 1.14 ± 0.10 was used, and the evaluation was performed in two steps: Phase 1, based on the inoculum source (autochthonous, AUT, and non-autochthonous, N-AUT); and Phase 2, based on the carbon source (lactate, ethanol, and formate) and low pH. In Phase 1, the sulfate removal using both AUT and N-AUT biomasses were similar, 53% and 59%, respectively. In Phase 2, ethanol and lactate as electron donors yielded similar sulfate removal efficiencies of 42% and 44%, respectively, at neutral pH. When the initial pH was reduced from 4 to 3, sulfate removal using formate remained nearly constant at 34%, whereas it reduced from 43% to 30% with lactate, and dropped significantly from 18% to 7% with ethanol. Denaturing gradient gel electrophoresis analyses for sulfate-reducing bacteria revealed their presence in all samples. Microbial activity and sulfate removal obtained for AUT cultures indicated that they possess the potential for use in local acid mine drainage decontamination processes.

Resumo em Inglês:

Abstract In the present work, the potential of native isolates of fungi strains to biodegrade vegetable tannins used in the tanning industry was evaluated. Penicillium citrinum showed to be more efficient for consumption of acacia tannin, reaching 94.85%. Aspergillus chevalieri needs a greater adaptation phase (48 h) in both acacia and chestnut medium, evidenced by the slow growth (0.022 h-1) and low biomass productivity (0.31 g.L-1. h-1). The acacia tannin presented a higher COD/BOD ratio (2.97) and lower total phenol content (68%) when compared to chestnut tannin. In addition, there was greater consumption of this tannin in the cultivations, which contradicts previous reports and corroborates the results obtained with FTIR analysis that suggests the biodegradation of acacia by Penicillium citrinum and aethiopicum. The expressive results obtained demonstrated that the biodegradation of condensed tannins may be a promising alternative, with the potential to minimize tannery waste.

Resumo em Inglês:

Abstract This research investigated the performance of two pilot-scale treatment plants: an activated sludge and a hybrid model type IFAS (Integrated Fixed-Film Activated Sludge), combining sanitary landfill leachate with domestic sewage treatment with the objective of removing organic substances. In order to assess the possible impacts on the treatment, three experimental phases were developed with leachate inputs in the influent composition: 5%, 10% and 20% of the total load of BOD. As can be seen from the results, even with the highest levels of leachate input, there were no significant changes in the behavior of the biological processes. Regarding the oxidation of nitrogen compounds, expressed in terms of TKN, approximately 90% removals were observed for the IFAS process in all the phases. In the Activated Sludge process, removal rates during the study were approximately 70%, indicating poor performance. The kinetic coefficients for the autotrophic metabolism related to the Activated Sludge process remained stable, while a progressive decrease was observed for each stage in the IFAS process. In general, the IFAS process presented better performance than the Activated Sludge process in terms of removal efficiency of nitrogen matter, as well as higher operating stability.

Resumo em Inglês:

Abstract Belo Horizonte, capital of Minas Gerais state, is a highly urbanized city located in the third largest metropolitan area of Brazil, being one of the most important cities in the country. There are several potential air pollutant emission sources in the studied area, such as industry and the vehicular fleet (1,669,884 vehicles in 2015). These can affect the air quality, which can have an impact on population health. Despite this critical scenario, few studies have been developed with the objective of evaluating the air quality in this city, especially regarding the identification of pollutant emission sources. Thus, the aim of this study was to identify and quantify atmospheric emissions by stationary sources of significant environmental impact in Belo Horizonte. The quantification of emissions was preferably performed based on chimneys monitoring data. However, in the absence of these data, estimates were made based on AP-42 guidelines. As a result, 75 chimneys were identified, belonging to 28 companies. Pollutant emission rates of 305, 235, 234, 224, 206, 180 and 63 t year-1 were observed for NOX, CO, TSP, PM10, PM2.5, SO2 and VOC, respectively. The results obtained can contribute to the diagnosis, modeling and management of air quality in Belo Horizonte.

Resumo em Inglês:

Abstract The present study evaluated the phosphorus removal in a Sequencing Batch Reactor (SBR - 2,500L) used to treat the wastewater from an office building in two steps: phase I-Enhanced biological phosphorus removal (EBPR) and phase II-co-precipitation using FeCl3 as precipitant. The raw sewage presented a high organic load variation ranging from 0.11 (phase I) to 0.66 (phase II) kgCOD.m-3.d-1. A better phosphorus removal performance was obtained during co-precipitation (from 19.0 to 1.2 mg.L-1 = 93% of efficiency) compared with biological removal (from 15.6 to 9.0 mgL-1 = 42% of efficiency). FISH analyses did not demonstrate a strong PAO inhibition; however, nitrifying and denitrifying organisms (NSO and PAE) showed a significant activity reduction during phase II. Therefore, the bench tests made to obtain the oxygen uptake rate (OUR) revealed a heterotrophic organisms activity significantly lower in phase II (46.8 mgDQOT.L-1) than phase I (211.8 mgDQOT.L-1), indicating metabolic inhibition. The co-precipitation processes enhanced phosphorus removal, bringing the SBR effluent into accord with state law requirements; however, the inhibitory effect of ferric chloride on microorganism activity was highlighted.

Resumo em Inglês:

Abstract This study describes the application of ZnO commercial oxide and ZnO/ZnFe2O4 mixed oxides to reduce the mercury ion (Hg2+) in the aqueous phase. The catalysts synthesized were characterized by thermogravimetric analysis, adsorption and desorption of N2, scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, photoacoustic spectroscopy and Mössbauer spectroscopy. The heterogeneous photocatalysis process was studied in synthetic effluent treatment containing mercury chloride (HgCl2) in a batch and solar reactor. The results indicated that commercial ZnO catalyst totally reduced the Hg (II), in all conditions and reaction systems studied. On the other hand, for the mixed oxides (ZnO/ZnFe2O4), there was a decrease in the reduction efficiency in the batch reactor, indicating no ability to reduce Hg(II) in the presence of sunlight.

Resumo em Inglês:

Abstract The impeller geometry is a determining factor for mixing efficiency in a stirred vessel. In this study, the effect of disc-blade intercepting angle on power number, just suspended speed and mass transfer coefficient was investigated in a multiphase system under turbulent conditions. The impellers used in this study were fabricated with 3D printing. The interactions between the experimental parameters were analysed using Response Surface Methodology (RSM). The impeller power number was found to have a linear positive relation with disc-blade intercepting angle from 30° to 90°. Beyond 90°, the impeller power number became lower with increment in the disc-blade intercepting angle. The results confirmed better suspension efficiency in the angle range of 50° to 120° in 5 wt% solid suspensions. The lowest specific power requirement (Ɛjs) at just suspension condition was observed in the angle range of 30° to 80°. The highest mass transfer coefficient was obtained for the impellers with disc-blade intercepting angle in the middle range. Two models were established on power number and mass transfer coefficient for various disc-blade intercepting angles. The study confirmed that the hydrodynamic and mass transfer performance of disc blade impellers could be maximized by changing the disc-blade intercepting angle for a selected system.

Resumo em Inglês:

Abstract Illicium verum Hook essential oil (EO) is composed mainly of trans-anethole (TA), which has therapeutic potential. The extraction is usually by hydrodistillation, taking long hours, leaving the process costly and product with lower quality. Thus, the present study sought to optimize dehydrated fruit fragmentation by Box-Wilson central composite design and EO extraction and EO quality using a 24-1 fractional factorial design. It is concluded that the fruits must be fragmented to sizes smaller than 425 μm using a knife mill. For hydrodistillation, the condition reported as ideal was granulometry < 0.425 mm, 8% mass, 1 hour and water volume of 200 mL. This process provided an EO yield of 10.2% and high-grade TA (96.6%), requiring shorter time of extraction.

Resumo em Inglês:

Abstract This study presents a numerical investigation of the dynamics of methane adsorption in granular activated carbon beds with bidisperse packing in order to reduce the void spaces between the adsorbent particles and to improve the storage capacity in adsorbed natural gas vessels. Two distinct particle sizes (d and D) were used for the packing of the bidisperse bed, and the following particle size ratios were investigated: δ = d/D = 1 (monodisperse bed), 1/5, 1/10, 1/15, and 1/20. Compared with the monodisperse bed condition, the results obtained showed that bidisperse packing increases bed density by about 30% and methane storage capacity by up to 20%. The results also showed that the charging time could be optimized by increasing the pressure drop applied to the bed and that the storage capacity can be increased by cooling the admitted gas in the vessel.

Resumo em Inglês:

Abstract Coal slurry pipe, being a new type of energy transportation mode, changes of the particle composition and the effect on other parameters are worth studying. Comparison of ring tube test measured data and batch grinding model simulation data shows that batch grinding model can predict the coal particle gradation to a certain extent. The effect of collision and wear of overcurrent components in the centrifugal pump, friction and collision between particles and piping and piping accessories, and initial particle size distribution during hydraulic conveying were also investigated by laboratory studies. Meanwhile, the effect of particle composition change on slurry viscosity, hydraulic resistance and minimum resistance critical velocity was studied based on the experimental data. The experimental and theoretical analysis indicates that the change of slurry particle composition can lead to the change of viscosity, resistance and minimum resistance critical velocity of the slurry. Moreover, based on the previous studies, the calculation model of minimum resistance critical velocity of coal slurry is proposed.

Resumo em Inglês:

Abstract In the present study, the thermal conductivities of ionic liquid + water in the concentrations 0.1-0.6 %w/w and temperatures (302.5-337.9 K) are determined. The thermal conductivity of aqueous 1-butyl-3-methylimidazolium bromide declined with increasing concentration and temperature. A quadratic model is developed for predicting the thermal conductivity of aqueous ionic liquid using response surface methodology with R2 = 0.99. A two-layered feed forward back propagation neural network 2-10-1 is also modeled with mean square error, root means square and absolute average error percentage of 0.005, 0.071 and 2.684, respectively. The thermal conductivity of nanofluid (γ-Al2O3/water) is estimated and compared with the ionic liquid solution at the same concentration and temperature range. Thermal conductivity enhancement ratios of aqueous ionic liquids are found to be more than nanoparticle suspensions.

Resumo em Inglês:

Abstract A computational methodology is proposed and applied to calculate the temperature effectiveness, P, and the logarithmic mean temperature difference (LMTD) correction factor, F, of TEMA E shell-and-tube heat exchangers with one-pass and fluids flowing in counter-flow. An arbitrary number of baffles is considered along with three different mixture conditions of the shell-side fluid. The methodology is based on various modeling considerations adopted in several publications addressing crossflow and shell-and-tube heat exchangers. Each section between two baffles is idealized as a crossflow heat exchanger with different shell-side mixing conditions. The obtained results are compared to available solutions from the literature, showing a very good agreement. New closed-form mathematical P relations and approximate F correlations depending on the number of baffles, very appropriate for preliminary computerized analysis and design procedures, are provided. A theoretical study about the influence of the number of baffles and two shell-side fluid mixing hypotheses over P and F values is presented. The proposed methodology could be used to obtain P and F values for a particular arrangement of 1-1 shell-and-tube heat exchanger.

Resumo em Inglês:

Abstract ZnO-NPs can be obtained through various methods, resulting in nanoparticles with different size and morphology, which directly influences their antimicrobial potential. The objective of this work was to evaluate the antibacterial activity of ZnO-NPs obtained by a solochemical process against important human foodborne pathogens: Staphylococcus aureus, Salmonella Typhimurium, Bacillus cereus and Pseudomonas aeruginosa. ZnO-NPs were identified as nanorods with the length between 90.1 and 100 nm (10.5 % frequency), the diameter between 80.1 and 90 nm (21 % frequency), and wurtzite type crystalline structure. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) were equal to 0.05 mg mL-1 and 0.5 mg mL-1 for S. aureus and S. Typhimurium, respectively, lower than previous results related in the literature. ZnO-NPs produced by solochemical method had a superior antibacterial activity. For instance, they can be incorporated in packaging materials for increasing microbial safety and food shelf-life by inhibiting bacterial growth.

Resumo em Inglês:

Abstract This study investigated the formation of composite particles of chitosan (CS) and theophylline (TPH) via supercritical assisted atomization (SAA) using aqueous ethanol (50%, v/v) as the solvent and supercritical CO2 as the spraying medium. According to XRD, DSC, and FTIR analyses, the crystal form of the SAA-treated TPH from the as-received TPH was unchanged. The effect of different mass ratios of CS to TPH on the in vitro release of TPH showed that the dissolution of the highly water-soluble TPH was retarded when included in the composite particles and could be controlled by the mass ratio of the component in the SAA process. The in vitro dissolution data showed a good fit with the Peppas-Sahlin model, which was used to conclude that the drug release from the composite particles resulted from a combination of drug diffusion and relaxation of the polymer. As the mass ratio of CS to TPH increased, the mechanism relating to polymer relaxation became crucial in the TPH-CS composite particles.

Resumo em Inglês:

Abstract The objective of this study was to evaluate the antioxidant activity of the natural extracts catechin, curcumin and quercetin on the oxidative stability of methylic cottonseed oil biodiesel. The oxidative stability was evaluated using the Rancimat method (EN 14112) for biodiesel with 500, 1000, 1500, 2000 and 3000 ppm of additives, and compared with the commercial antioxidant butyl hydroxyanisole at the same concentrations. Kinematic viscosity was also evaluated at the same concentration. All additives had a positive effect on the oxidative stability; moreover, all extracts presented better results than BHA. Catechin was the most effective additive, achieving an induction period almost three times greater than BHA for 3000 ppm. In addition, all three extracts caused a reduction in kinematic viscosity, but it remained within the technical specification. These results prove catechin, curcumin and quercetin to be powerful natural antioxidants.

Resumo em Inglês:

Abstract The aim of this study was the synthesis of composites containing hydroxyapatite (Hap) or silicon substituted hydroxyapatite (HapSi), carboxyl functionalized carbon nanotubes (fMWCNT) and gelatin (G) in different ratios. Ibuprofen (IBU) was chosen as a model drug for the formulation of extended-release dosage forms. The obtained composites were characterized using X-ray diffraction, laser diffraction particle size analyzer, Brunauer-Emmett-Teller surface area measurements, transmission electron microscopy and Fourier transformed infrared spectroscopy. IBU adsorption and desorption was monitored by UV-VIS spectroscopy. The obtained results revealed that composites containing three components exhibit higher adsorption efficiency (Hap-fMWCNT-20G - 82.7% and HapSi-fMWCNT-20G - 84.6%) and extended-release of IBU, due to the chemical bonds between the carboxyl groups of IBU and the functional groups on the composite surface. The adsorption capacity of Hap composites is important for dental or orthopedic implants, the anti-inflammatory substances being adsorbed on their surface; but the adsorption capacity also enhances new bone formation (osteosynthesis) around the implants. These composites are thus attractive materials to be used in bone tissue engineering and drug delivery systems.

Resumo em Inglês:

Abstract The feedstock cost can comprise more than 75% of the overall biodiesel cost, and then economic issues are the main limitations of biodiesel production. This research focused on the use of alternative feedstock and production processes. The production of fatty acid esters from residues becomes an interesting alternative route since it is possible to reduce the cost of the process. The present work aimed to produce methyl esters from the residual oil of the poultry industry, using a commercial soluble lipase Eversa Transform 2.0® (NS-40116). The effects of methanol (1.2 to 1.8 eqv), water (1 to 2 wt%) and enzyme (0.1 to 0.5 wt%) contents on reaction conversion were evaluated through a 2³ experimental design with three central points, at 45 ºC, 250 rpm for 16 and 24 h of reaction time. From the results, by using 0.3 wt% enzyme, 1.5 wt% water, and 1.5 eqv of methanol it was possible to reach the most effective esters conversion (90.61%).

Resumo em Inglês:

Abstract Solid-state hydrogen storage is of considerable concern as a potential hydrogen source for portable fuel cell applications. This study mainly focuses on kinetics of NaBH4/Al2O3 nanoparticles (20 nm)/H2O system with CoCl2 as catalyst and the factors that affect the hydrogen generation rate (HGR). It is observed that the reaction rate increases considerably with increase in NaBH4, Al2O3 nanoparticle (20 nm), CoCl2 and NaOH concentrations and the respective reaction orders are calculated. Hydrogen generation rate is also investigated at different temperatures (303, 313, 323 and 333 K) for constant NaBH4 (1.25 moles/L), NaOH (1.4 moles/L), CoCl2 (0.02 moles/L) and Al2O3 (0.09 moles/L) concentrations. Kinetics of the NaBH4 hydrolysis reaction increases with γ-Al2O3 nanoparticles and the calculated activation energy is 29 kJ/moles. This study also reports that a combined dual-solid-fuel system is highly efficient in terms of hydrogen storage capacities compared with a single hydride based system. Maximum hydrogen generation efficiency, observed at a mass ratio of 0.09: 0.7 (Al2O3/NaBH4), is 99.34%.

Resumo em Inglês:

Abstract This study aimed to optimize ultrasound-assisted palm oil-in-water nanoemulsions. The influence of hydrophilic-lipophilic balance (HLB), oil and surfactants concentrations, ultrasound intensity and processing time were investigated by means of two experimental designs. Desirability profiles were applied to detect the optimal conditions for preparing the nanoemulsion. Stable nanoemulsions with small droplet size and polydispersity index (PDI) were obtained at an HLB of 6.5, oil and surfactant concentrations of 2.8 wt%, ultrasound intensity of 200 W.cm-2 and processing time of 15 minutes. The nanoemulsion presented stability for 30 days at three different temperatures (4°C, 25°C and 40°C), which makes it suitable for application in the food and cosmetic industries. Ultrasound was shown to be a promising technology to produce nanoemulsions containing palm oil.

Resumo em Inglês:

Abstract Repeated heating of fat oil may result in the formation of highly toxic aldehyde compounds. The oils having such compounds are considered as health hazards and therefore their repeated use is banned in many countries. Since huge quantities of the used oil need urgent disposal, this work is focused on the disposal of used oil for the resource recovery. The waste fat oil was converted into useful fuel through catalytic and non-catalytic pyrolysis. The catalyst was used to lower the oxygen content and to increase the amount of the hydrocarbons in the oil product. The pyrolysis reaction was catalyzed by three catalysts of the clinker type, namely ordinary Portland cement, white cement and burnt clay/clinker powder. The pyrolysis reactions were performed using a custom-made furnace and stainless steel pyrolyzer. Optimum temperature, time and catalyst quantity were identified for high liquid and gaseous fractions and low solid residue. The oil obtained during each reaction was characterized for chemical composition by using GC-MS technique. The oil product of simple pyrolysis, cement catalyzed, white cement catalyzed and clinker catalyzed pyrolysis had the hydrocarbon contents of 3%, 19%, 51% and 93%, respectively.

Resumo em Inglês:

Abstract Plant oils and their derivatives have been vigorously exploited as alternatives for synthesis of epoxides due to depletion of petroleum resources. In this study, crude jatropha oil (CJO) was subjected to a transesterification process to form jatropha methyl esters (JME) using peroxyacetic acid generated in situ from hydrogen peroxide and acetic acid via an acidic ion exchange resin (AIER). The effect of temperature, molar ratio of hydrogen peroxide to unsaturation, molar ratio of acetic acid to unsaturation, and catalyst loading were investigated. This study revealed that the maximum 89.9% relative conversion to oxirane rings was achieved after 6 h with the optimal reaction conditions of temperature at 70 ˚C, the molar ratio of hydrogen peroxide to unsaturation of 1.5 mol, the molar ratio of acetic acid to unsaturation of 0.5 mol, and catalyst loading of 16%. Fourier Transform Infrared (FTIR) spectra of the epoxidized jatropha methyl esters (EJME) showed oxirane peaks (doublet) at 825 and 843 cm-1.1H NMR confirmed the diepoxide group at 2.85 ppm and 2.98 ppm, while the diepoxide signals of 1C NMR were present at 56.88-57.06 ppm. Production of bio-epoxides from Jatropha methyl esters hence looks promising with favorable physicochemical properties, availability, and versatility.

Resumo em Inglês:

Abstract The main objective was to evaluate the stability and toxicity of a Solution Enhanced Dispersion by Supercritical Fluids (SEDS) formulated A. paniculata extract that was intended for food applications. The best formulated SEDS A. paniculata extract with improved dissolution of andrographolide (data not shown) was obtained using 25 mg/mL A. paniculata extract (maceration in acetone) and 6 mg/mL Eudragit L100-55 with acetone as feed solvent at the following SEDS co-precipitation conditions: 150 bar, 40 ̊C, 15 L/min CO2 flow rate (1 bar, 25 ̊C), 0.5 mL/min liquid feed flow. Sticky A. paniculata extract with 16% w/w andrographolide was transformed into SEDS co-precipitates concentrated with 20.4% w/w andrographolide. Only 20-30% of andrographolide was degraded after two-month storage under 5, 30, 45 ̊C at 75% relative humidity (RH). About 30-60% of andrographolide was degraded after addition into drinking water, orange drink, soybean milk for a day. This would imply its unstable nature after being dispersed and wetted in liquid food. SEDS co-precipitate was found to be practically acetone-free (< 0.1 ppm) by Headspace Gas Chromatography-Mass Spectrometry (GC-MS). This showed the capability of the SEDS process in stripping off acetone. Higher cytotoxic potential of SEDS co-precipitates (LC50 = 46.46 µg/mL) than extract (LC50 = 150.45 µg/mL) was observed.

Resumo em Inglês:

Abstract A solid catalyst for biodiesel production was synthesized from dolomite by calcination at different temperatures of 800 and 900oC for 2 h. The catalyst was characterized by scanning electron microscopy (SEM) and Brunauer Emmett Teller (BET). Its performance in the production of palm kernel biodiesel (PKB) using palm kernel oil in an optimization study was carried out by a definitive screening design. The varying process parameters for the optimization were methanol:oil molar ratio, reaction temperature, catalyst quantity, reaction time and dolomite calcination temperature. Tendency and extent of the catalyst reusability were also studied. The catalysts were found to contain calcium and magnesium oxides with morphological structures of: surface areas 507 and 560 m2/g, pore volumes 0.180 and 0.199 cm3/g, and pore sizes 27.07 and 31.48 Ȃ for Dolomite Catalyst Calcined (DCC) at 800oC (DCC800) and DCC at 900oC (DCC900), respectively. The optimal parameters of methanol:oil molar ratio 12:1, temperature 65oC, catalyst quantity 8% (w/w), time 4 h and DCC800 gave an optimum yield of 98.69% biodiesel. The catalyst was reused for the 8th cycle after which the %yield of PKB decreased by <4%. It can be concluded that the dolomite catalyst has a great activity and potential as a viable catalyst for quality biodiesel production.

Resumo em Inglês:

Abstract We applied ultrasonic technology for the transesterification of soybean oil catalyzed by a mixture of lipases (combi-lipase: 75 % Novozym 435; 10 % Lipozyme TL-IM; and 15 % Lipozyme RM-IM), verifying the effects of ultrasonic amplitude, pulse conditions, the ethanol:oil molar ratio, enzyme concentration, and the influence of solvent (tert-butanol on the reaction. We also compared this system against ultrasound combined with mechanical stirring, and the efficiency of the combi-lipase, compared with the individual use of each lipase. The optimum conditions for the transesterification reaction were determined as enzyme concentration of 15 % (in relation to oil mass); ethanol:oil molar ratio of 3:1; ultrasonic amplitude of 30 %, duty cycle of 50 % and time pulse of 15 sec. The yields of conversion of ethyl esters with and without solvent were similar, indicating that the use of solvents during enzymatic transesterification reactions is not necessary when ultrasonic technology is applied to the system. The combination of mechanical stirring and ultrasound did not improve the yields of conversion compared to ultrasonic technology alone. The proposed combi-lipase produced higher yields of ethyl esters (75 %) than the individual lipases (55 %) in 5 h under ultrasonic-assisted batch reactions.

Resumo em Inglês:

Abstract This study aims at clean production of 2-ethylhexyl palmitate catalyzed by lipase Fermase CALB 10000 in a solvent-free system using ultrasound technology. The central composite design (CCD) of response surface methodology with 4 factors at 3 levels consisting of acid to alcohol molar ratio (1:3-1:7), enzyme loading (3 %-7% (w/w)), ultrasound power (60 - 100 W) and duty cycle (30%-70 %) was used for optimization of the reaction. All the reactions were carried out at a fixed temperature of 60°C, 200 rpm and reaction time (120 min). The statistical software, Design-Expert 9.0, was used for regression analysis and graphical analysis of the responses obtained by running the set of designed experiments. The polynomial equation of quadratic order was employed to fit the experimental data. The operating conditions for optimum synthesis of 2-ethylhexyl palmitate were molar ratio of 1:5.5, 5.61 % (w/w) of the enzyme with ultrasound power 79.54 W and duty cycle 48.04 %, leading to a reaction conversion as high as 96.56% in 120 min. The operational stability of the enzyme was maintained at >70% conversion up to 5 cycles. Thus, ultrasound is a promising green technology for the lipase catalyzed synthesis of ethylhexyl esters.

Resumo em Inglês:

Abstract Extractive desulfurization with ionic liquids has attracted significant attention from a growing number of scientists due to the current environmental restrictions on fuel. Protic ionic liquids (PILs) were synthesized via equimolar neutralization of morpholine and formic-based compounds. The obtained PILs were characterized by Fourier transform infrared and 1H NMR spectroscopy and used as a promoter for the room temperature deep desulfurization of model oil and commercial B0S500 diesel. Extractive desulfurization of the model oil in n-octane showed that the alkyl chain length of the ionic liquid [Nmorph]+[HCOO]- does not enhance the efficiency of dibenzothiophene (DBT) removal. Regardless, the [Morph]+[HCOO]- IL is the most promising candidate for extractive desulfurization. The best results were obtained using multistage extraction (n = 3) and a 1:1 volume ratio, resulting in a 99.44% removal rate of sulfur compounds. For commercial B0S500 diesel, extraction time significantly influenced the removal of sulfur species. For samples with multistage extraction and a 1:1 volume ratio, [Morph]+[HCOO]- removed approximately 47.48% of the sulfur-containing compounds. The recycling study of [Morph]+[HCOO]- suggests that the IL remains active for up to three operating cycles without losing efficiency.

Resumo em Inglês:

Abstract The concern about the effective use of agro-industrial residues from the food industry has increased. Bromelain is an enzyme mainly obtained from the pineapple plant (A. comosus), including its parts normally considered as waste. It is a high value-added product with a wide variety of applications such as in food, cosmetic and pharmaceutical industries. Many approaches have been used to purify this enzyme, but an efficient method to produce highly active and pure bromelain is still highly desirable. The investigated methods include ion exchange chromatography, precipitation, an aqueous two-phase system as well as affinity and filtration membranes. This paper gives an overview about the advantages and limitations of each one. Chronologic results and advances for these separation processes are also shown. The major tendency is the use of combined processes, such as hybrid or integrated ones.

Resumo em Inglês:

Abstract Hydroalcoholic extracts prepared by conventional methods (in stirred vessel at 25 °C and 1 bar) and, hydroalcoholic and supercritical carbon dioxide (scCO2) extracts prepared in fixed bed extractors (60 ºC and 400 bar) were obtained from pitanga leaves (Eugenia uniflora L.) in order to recover phenolic compounds. Hydroalcoholic and ethanolic extracts obtained in fixed bed were further fractionated in four separators by gradual pressure reduction, using scCO2 as an antisolvent. All extracts and fractions were characterized in terms of extraction yield and the presence of total phenolics and flavonoids. Solvents were found to significantly influence the extraction yields and composition. Yields increased as a function of polarity, whereas the hydroalcoholic extractions displayed the highest yields and the highest amounts of extracted phenols and flavonoids.

Resumo em Inglês:

Abstract In this work, vapor - liquid (VLE) equilibrium for the binary system carbon dioxide (1) + coumarin (2) at high pressures was measured by a static synthetic method using a variable-volume view cell. Experimental data were obtained in the temperature range of 318 - 338 K and pressures up to 20 MPa. Coumarin molar fraction ranged from 3.0x10-3 to 6.0x10-3. Coumarin melting point reduction at high pressures was observed. The experimental results were modeled using the Peng-Robinson (PR) equation of state with van der Waals quadratic mixing rules (vdW - QMRs), providing a good representation of the experimental phase equilibrium data. Critical properties and the acentric factor were estimated using the Constantinou and Gani method, which showed to be satisfactory on the quality of data correlation. Results indicate coumarin solubility increases with increasing phase transition pressure at a given temperature.

Resumo em Inglês:

Abstract This paper presents a thermodynamic model developed for a prototype absorption chiller using NH3/LiNO3 with 10 kW of nominal capacity. The study was undertaken using thermodynamic modeling based on the mass and energy balance, takes the overall heat transfer coefficients into consideration and uses the characteristic equation method. First, the results obtained from the thermodynamic modeling developed were compared with those obtained from the characteristic equations of thermal power activation and the cooling capacity. These showed good agreement with the experimental data, there being maximum relative errors of around 5% for most of the operational conditions of the system. Secondly, a parametric analysis was made by altering the variables, such as temperature, mass flow rate, and configuring the heat dissipation that influences the overall performance of the prototype chiller.