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Arthrospira platensis has stood out, especially due to its high protein content and its potential for food application. However, the exploration of protein concentration techniques of this microalgae still presents a great challenge. Thus, the objective of this study was to evaluate the purification of A. platensis proteins by applying two different aqueous two-phase systems (ATS) composed of potassium phosphate and ethanol, and sodium citrate and ethanol, in addition to the association with membrane separation process (MSP), and the characterization of the fractions obtained. ATS under the optimised conditions (19% potassium phosphate and 30% ethanol, and 19.5% sodium citrate and 29% ethanol) resulted in 1.27 and 1.31 purity, and 77.45% and 78% recovery, respectively. The sodium citrate and ethanol ATS showed significantly greater purity; thus, the upper phase was submitted to MSP. The association of ATS and MSP increased the recovery (~ 87%) and the purity (1.5). The top phase of ATS showed higher protein content (61%) than the bottom (5.9%), confirming the protein preference to the top. When the MSP was evaluated, the protein was increased about 8.0%, and antioxidant activity was kept (42 and 40% to top phase and ATS/MSP concentrate, respectively). Emulsions formed by ATS top phase showed a lower droplet size (33.69 µm D4.3 and 6.02 µm D3.2), and a significantly lower degree of overall destabilization (0.04 × 10–6 s−1 kh and 3.54 × 10–3 s−1 ks) than those stabilized with bottom phase and MSP/ATS concentrate. ATS associated with membrane process showed efficiency in the concentration A. platensis protein, being able to be an alternative to be used in industrial systems.

The present work proposes a study on the combination of artificial neural network based model and multivariate calibration techniques, as principais component analysis (PCA) and partial least squares (PLS) combined with near infrared spectrophotometer (NIR) to formulate online water content monitoring models for recovered fuel oils after effluent treatment of a Brazilian thermoelectric plant. The database for adjustments of these models was built using oil samples supplied by the SUAPE II thermoelectric plant, where they were characterized in laboratories and analyzed via NIR. 450 spectra were used to construct the PLS model for predictive model calibration using the PLS technique and 118 spectra for the model based on artificiais neurais networks. In the obtained PLS model, it was possible to obtain correlations around 0.97, cross-validation error (RMSECV) of 0.0906 and test prediction error (RMSEP) of 0.0651. The RNA model presented coefficient of determination R² of 0.99 for training and R² of 0.98 for test with prediction error of 0.062

Commercial chiral stationary phases (CSPs) are based mainly on polysaccharides supported on silica; however, the pharmaceutical industry shows a special interest on chiral separations, exhibiting high financial investment in the development of new CSPs. These can be structured by a new optically active compound or different support. Thus, metal–organic frameworks (MOFs) are crystalline materials that arise with great potential for support, due to its high porosity, the strong intermolecular force between the metal and the ligand selectivity, and high adsorption capacity. Interested in this, this work proposes a new CSP using the metal–organic structure ZIF-8 (Basolite Z1200) due to its high mechanical stability. To this end, it is proposed the modification of the ZIF-8 with the optically active compound, tris-3,5-dimethylphenylcarbamate amylose. Through characterization textural, structural, and physicochemical performed, it is possible to confirm the synthesis of the chiral compound (amylose carbamate), as well as the functionalization of the metal–organic structure with tris-3,5-dimethylphenylcarbamate amylose (ZIF-8-PEI-CA). In addition, as a validation technique, HPLC can detect the presence of enantiomers present in the racemic mixture of Troger bases.

The high protein content of Arthrospira platensis makes this cyanobacterium a great component of food. Thus, the protein obtained should guarantee the nutrient characteristic, in this case, as bioactivity and techno-functional properties. Membrane separation processes (MSPs) have been highlighted by their capacity to separate proteins and keep their properties. Therefore, MSP was used to concentrate and separate the proteins from A. platensis, which were characterized by their physicochemical and techno-functional properties. Different ultrafiltration (UF) membranes and operational conditions (10- and 50-kDa pore size, conventional and tangential flow, hollow fiber type and pressures of 1.0, 1.5, and 2.0 bar) were tested and associated with diafiltration (DF). The maximized condition of UF/DF (hollow fiber, 50 kDa, tangential flow at 1.5 bar, associated with one DF) was up scaled (pilot scale) and allowed concentrate and permeate fractions with 81.75% and 61.20% of protein, respectively, to be obtained. A protein concentrate with 142 mg L−1 of phycocyanin, 90% of antioxidant activity, with proteins more soluble at high pH (50% soluble protein at pH 7.0) and molecular weight among 5–15 and 100 kDa, was obtained. Protein thermal and emulsifying properties were maintained by the MSP, and the concentrate fraction presented results similar as A. platensis biomass, which confirms the advantage of this method in guaranteeing the protein quality.

The development of online monitoring techniques is of great relevance for understanding the structural changes of proteins under different conditions in order to maximize their catalytic activity. This study aimed to evaluate the potential of the NIR (near-infrared spectroscopy) technique for the monitoring of alterations of secondary and tertiary structures of Horseradish peroxidase (HRP), an oxidoreductase that has several applications in the industrial environment, food industry and bioremediation. The NIR associated to the multivariate calibration, through the PLS (partial least square) method allowed the construction of a robust model for the prediction of the analysis. The values of the correlation coefficient (R²), root mean square error of calibration (RMSEC), root mean square error of prediction (RMSEP) and root mean square error of cross validation (RMSECV) for secondary structure analysis using circular dichroism (CD) data as reference (actual values) were 0.9681, 0.647 (mdeg), 0.945 (mdeg), and 1.12 (mdeg), respectively. For tertiary structure analysis, fluorescence spectroscopy (FL) data were used as reference. R2, RMSEC, RMSEP and RMSECV were, respectively 0.9999, 1.95 (a.u.), 2.09 (a.u.); and 2.19 (a.u.). NIR combined multivariate calibration showed promising results for sctructural changes monitoring of HRP.

Structural, chemical, morphological, and hydrophilic surface characteristics of SBA-15 silica synthesized by hydrothermal method in an autoclave and in a microwave-heated reactor were analyzed in this work. The influence of time and temperature on these characteristics was investigated. Materials were characterized by textural analysis (BET), FTIR, TGA, XRD, goniometer contact angle, SEM, and TEM. It was possible to obtain SBA-15 silicas assisted by microwave heating irradiation with short-time synthesis (0.5–8 h) compared with the hydrothermal classic method (24 h). Materials presented surface area between 650 and 850 m2 g−1. Through the XRD and TEM results, it was observed that mesostructured materials with two-dimensional, long-range, and hexagonal ordered channels are characteristic of SBA-15. This study showed that heating by microwave irradiation during silica synthesis generates materials with a greater amount of silanol groups. It is possible to control the surface properties of SBA-15 during the microwave-assisted synthesis through temperature tuning. Higher temperature provided SBA-15 with higher hydrophilicity.

Hancornia speciosa has bioactive molecules such as phenolic compounds which exhibit antioxidant and antimicrobial properties. Nevertheless, the separation of these substances from a medicinal plant can be different according to the extraction process and solvent used. Thus, the present study aimed was to separate phenolic compounds from Hancornia speciosa leaves in three steps by using a sequential pressurized liquid extraction and evaluated their antioxidant and antibacterial activity. Results showed that the temperature increase from 25 to 60° C provides a significative enhancement in the extraction yield. The raw ethanol extract (39.0 ± 0.2%) showed the highest overall extraction yield. However, fractionated ethanol extract (FEE) at 60 °C exhibited the highest amount of total phenolic compounds (347.0 ± 4.12 mg/g extract). Fractionated ethyl acetate extract (FAE) at 60 °C presented improved quantity of total flavonoids (230.4 ± 3.5 mg/g extract) and rutin content (16.6 ± 0.3 mg/mL extract). The antioxidant activity results for IC50 of DPPH indicated that FEE (3.8 ± 0.1 µg/mL) was the best free radical scavenger. FAE and FEE were able to inhibit the growth of multidrug-resistant E. coli.

The synthesis of adequate adsorbents and efficient methods to separate CO2 present in natural gas streams in petroleum industry has been receiving increased attention in academic and industrial centers. The presence of CO2 in those streams causes serious inconvenient in the transport and processing of natural gas. In this work, the synthesis of pure (SA) and functionalized with (3-aminopropyl) triethoxysilane (APSA) silicas aerogel was performed under microwave irradiation and subsequent drying with supercritical CO2 (SC-CO2). Materials were characterized in relation to their surface area (BET), pore volume (BJH), thermal decomposition (TGA), carbon, hydrogen and nitrogen content (CHN), functional groups (FTIR) and morphology (SEM). The results indicated a modification of the surface of silica with APTES. In addition, the methodology for synthesis and drying of the silica aerogel was efficient and reduced the total time of synthesis. Materials were used as adsorbents in the separation of CO2/CH4 mixtures by using a high-pressure adsorption cell coupled to a near infrared spectroscopy (NIR) probe to monitor CO2 and CH4 concentrations. Adsorption experiments were conducted at 20°C, pressures from 90 to 120 bar and CO2 concentration in the mixture up to 10 mol%. Silica APSA presented adsorptive capacities of 3.30 mmol g−1 at 90 bar and 10.20 mmol g−1 at 120 bar, better than those obtained with the commercial 3-aminopropyl-functionalized silica gel (APSC) of 0.88 mmol g−1 at 90 bar and 9.43 mmol g−1 at 120 bar. NIR was able to quantify the adsorption of CO2 at high-pressure.

Phenolic compounds are toxic pollutants that are harmful to the human body and aquatic environments, with carcinogenic potential and frequently found in industrial effluents at high levels....

In this study, the extraction yield, the mathematical modeling of pressurized liquid extraction (PLE) kinetics with sub- and supercritical carbon dioxide (SC-CO2) of olive leaves (Olea europaea) and the biological activity of the extracts were evaluated. The extraction with PLE was conducted isobarically (10.3 MPa), varying the temperature (20, 40 and 60 °C) and the solvent (ethyl acetate, acetone, ethanol, ethanol:water—80:20, v:v), solvent flow (2 mL min−1) and time (110 min) and the extractions with SC-CO2, varying the temperature between 20 and 60 °C and the pressure between 8 and 25 MPa, keeping the time constant (210 min) and the CO2 flow of 2 mL min−1. In the extracts, antioxidant activity, total phenolic and flavonoid contents and oleuropein were evaluated. The highest total extract yield in the PLE was 30.91% at 60 °C, 10.3 MPa using ethanol:water (80:20, v:v). The yield obtained using the supercritical fluid was 0.68% at 60 °C and 25 MPa. The PLE extract obtained with ethanol at 60 °C presented the highest concentration of total phenolic content (386.42 mg GAE g−1 extract), total flavonoids content (33.43 mg CAT g−1 extract), oleuropein (73.65 mg g−1 extract) and antioxidant activity (82.87%). The overall extraction curves were modeled using the well-established Sovova model and kinetic extraction model based on the Brunauer–Emmett–Teller theory of adsorption. Both kinetic models used were able to correlate well with the experimental data with slightly better results obtained by the former. The alternative PLE extraction technique investigated in this work was found to be suitable for the extraction of olive leaves after short times of extraction obtaining an extract with high biological activities.

Aprotic ionic liquids ([C4pyr]+[NTf2]-, [C8mim]+[NTf2]-, [C8mim]+[OTf]-, [C8mim]+[PF6]-, [C8mim]+[BF4]-, [C12mim]+[NTf2]-, and [C12mim]+[Cl]-) were successfully evaluated as viscosity modifiers, emulsion inhibitors, and demulsifiers. They are prone to be applied for the heavy oil production since such crude oil type potentializes some issues that are typically observed in the petroleum industry. Among them, it is worth highlighting the low flowability due to the oil's high viscosity. Also, high-viscous crude oil usually generates stable emulsions since they have high resins and asphaltene contents, which are interfacial-active. Thus, for operational and economic reasons there is a need for technologies that facilitate the improvement of the heavy-oil flowability as well as the demulsification process. Then, this work aimed to analyze the influence of the ionic liquid chemical structure (cationic alkyl length, cationic functional group, and anion type) upon the oil viscosity, emulsion inhibition or demulsification, at concentrations of 5 and 100 ppm (m/m). Two Brazilian heavy-oils were used for this study. Viscosity measurements of these oils at room temperature (25 °C) were made by an oscillatory rheometer before and after the addition of ionic liquid. Also, the emulsification inhibition and demulsification efficiency were analyzed by centrifugation. The results showed that the 1-dodecyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide promoted a demulsification efficiency higher than 99%. In turn, the 1-butylpyridinium bis(trifluoromethylsulfonyl)-imide was the one that worked as an emulsion inhibitor. On the other hand, the interaction between the studied oils and some of the used ionic liquids enhanced the oil viscosity. All the evidence points out to the fact that it was caused by the asphaltene aggregation due to the formation of an ionic liquid-asphaltene molecular structure. The observed viscosity increase was of 11% for oil A and 7% for the oil B.

The energy industry has registered a considerable growth of petroleum production from reservoirs located in deep and ultra-deepwater, mainly in Brazil. The Brazilian Pre-Salt fields, specifically, have shown high carbon dioxide content which favors the precipitation of organic particles such as asphaltenes. This scenario has turned flow assurance into a major technical and economic challenge for the exploitation of those fields. In this work a variable-volume cell equipped with a near-infrared probe was used to study the onset of asphaltene precipitation induced by carbon dioxide, evaluating the effects of pressure, temperature, asphaltene concentration, and system composition. Furthermore, the Cubic Plus Association (CPA) was applied to model the asphaltene precipitation. The results show that temperature and the oil model system composition were the parameters that most influenced the asphaltene stability, and that the CPA adequately described the asphaltene precipitation.

The large volumes of natural gas production mean that the processes currently used in the oil industry no longer meet such demand. Therefore, there is an expectation that adsorption processes will reach up to 200 bar in order to process the large volume of natural gas produced. However, it is not known if the materials used in this process would remain stable after being subjected to high pressures. In this way, sorption studies of host molecules such as CO2 at high pressures are important to understand the structural, thermal and chemical changes of this material. Therefore, the objective of this work is to perform stability experiments with MOF-177 using CO2 in an equilibrium cell at a fixed pressure of 200 bar at different temperatures of 20 °C, 40 °C and 60 °C for 12 h. The X-ray diffraction measurements showed that the metal-organic structure underwent irreversible amorphization with increasing temperature. The samples treated at 20 °C and 40 °C did not show significant surface area changes. However, at 60 °C there was an expressive reduction. All samples showed thermal stability up to 400 °C. By means of the FT-IR and SEM analysis, it was possible to observe that there was no chemical and morphological change in the MOF-177 and in the samples submitted to high pressure at different temperatures.

Sol-gel technique aiming enzymatic immobilization in situ with ionic liquids as additives is poorly studied. In this process, the addition of the enzyme is carried out in the synthesis of the support. The characteristics of ionic liquids, such as low vapor pressure, thermal stability, and non-flammability, make them strong candidates for use as immobilization additives. The objective of the present study was to immobilize the Candida antarctica B lipase by the sol-gel technique using ionic liquids as additives. The optimum points determined for ionic liquids 1-butyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium bromide, and 1 hexadecyl-3-methylimimidazolium were 0.30, 0.27, and 0.22 g/mL of enzyme and 1.60, 1.52, and 1.52% of additive, respectively. The amount of enzyme and ionic liquids used in aerogel immobilization was the same as the optimized values in the xerogel immobilization process (for each ionic liquid). Ionic liquids proved to be good additives in the enzymatic immobilization process. Xerogel, regardless of the ionic liquid, presented a greater number of use cycles and better thermal stability compared to aerogel.

Microbial biofilms, structured communities of microorganisms, have been often associated to the infection and bacterial multiresistance problem. Conventional treatment of infection involves the use of antibiotics, being an alternative approach is the use of red propolis, a natural product, to prepare polymer nanoparticles. The aim of the present study was to encapsulate red propolis extract in poly(lactic-co-glycolic acid) (PLGA) nanoparticles for destruction in vitro of pathogenic biofilms. Poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) containing red propolis hydroethanolic extract (2 mg/mL) were produced by emulsification solvent diffusion method. The extract and developed nanoparticles were analyzed for antimicrobial activity and inhibition of bacterial biofilm formation in vitro against Staphylococcus aureus and Pseudomonas aeruginosa. Transmission electron microscopy images confirmed spherical nanoparticles in the range size from 42.4 nm (PLGA NPs) to 69.2 nm (HERP PLGA NPs), with encapsulation efficiencies of 96.99%. The free extract and encapsulated in polymer nanoparticle presented antimicrobial potential, with a minimum inhibitory concentration from 15.6 to 125 μg mL−1 and from 100 to 1560 μg mL−1 to inhibit biofilm formation for the Staphylococcus aureus and Pseudomonas aeruginosa, respectively.

Antineoplastic potential in human breast adenocarcinoma, cervical cancer cells and cytotoxicity in non-tumoral cells was assessed using Pecan nut (Carya illinoinensis L.) oil. The global yield of Pecan oil extracted by Goldfish method (GD) ranged from 23.53% (1 h) to 47.73% (6 h) whereas than by pressurized ethanol extraction (PEE) and pressurized propane extraction (PPE) it was obtained a maximum global yield of 32.43% and 54.79%, during 40 min, respectively. Chromatographic profiles indicated the presence of palmitic, stearic, oleic (main compound), linoleic, linolenic, caproic and arachidic acids. Cervical squamous cancer cells (SiHa), breast cancer cells (MCF-7) and non-tumoral immortalized human keratinocytes (HaCat) were treated with different concentrations of oils by 24 h and cell viability was measured by MTT assay. The extracts obtained from Goldfish method showed the best results for the treatment of cervical cancer cells (IC50 of 16.46 μg mL-1 and selectivity index of 0.75).

The increased demand for biotechnological processes in industrial applications requires the development of highly active and stable heterogeneous biocatalysts. For this reason, the present work aimed to study the immobilization process by physical adsorption of lipase from Burkholderia cepacia (BCL) on aerogel modified with protic ionic liquid (2-hydroxy-N-methylethanaminium pentanoate – C5). The adsorption study of BCL on aerogel modified with protic ionic liquid (Aerogel-IL) has been performed and compared with unmodified support (Aerogel-Control). It was observed that the modification of aerogel allowed a greater retention of BCL (337 mg.gsupport –1 or 977.7 U.gsupport –1) than the unmodified support (297 mg.gsupport –1 or 863.5 U.gsupport –1). Experimental data obtained in physical adsorption of BCL on Aerogel-IL and Aerogel-Control were well-fitted to Sips and Redlich-Peterson isotherm models, respectively. BCL adsorption on both supports was found to be a spontaneous process. Immobilized BCL on Aerogel-IL has shown a better thermal stability than free and immobilized BCL on unmodified support being active for more than 14 days. These results reveal that the modified aerogel prepared in this work can be a promising support to prepare stable and active biocatalysts.

It is recognized that asphaltenes have a tendency toward aggregation and precipitation. Even at low concentrations, they can adsorb at interfaces/surfaces where each type of interaction plays an im...

The non-catalytic esterification of oleic acid with supercritical ethanol was carried out in a tubular reactor at different temperatures (150–300 °C), molar ratios (1:1–6:1) and volumetric flow rates (0.001–0.005 dm3/min). The highest free fatty acid conversion was obtained at 300 °C, ethanol to oleic acid molar ratio of 6:1 and fixed pressure of 150 bar. A phenomenological axial dispersion model was developed to evaluate the intrinsic effects of the operating variables on the conversion of oleic acid to ethyl oleate. The density of the reaction mixture was estimated using the Peng-Robinson equation of state. Distinct experimental data set were used for parameter estimation and validation of the model. The results demonstrated that the correction of the flow velocity is necessary, and that the axial dispersion effect cannot be neglected.

In the present work NIR detection capacity for biocatalytic oxidation of guaiacol catalyzed by horseradish peroxidase (HRP) was evaluated. UV–vis absorbance values were established as parameters for NIR spectra calibration. HRP was treated at 30 and 45 °C during 5 h, diluted 100x and 200x, and subsequently applied in the oxidation of the guaiacol. The spectral bands adopted for NIR monitoring was 900–1450 nm. Absorbance variations represents the bonding or breaking of certain bonds in the guaiacol conversion and tetraguaiacol molecule structuring. Four specific intervals of the NIR spectra were analyzed (940–1000 nm / 1010–1080 nm / 1116–1230 nm / 1240–1350 nm). The results indicate that in the spectral band studied, it is possible to monitor the formation of product in the medium using Near Infrared (NIR) spectroscopy, since high correlation values were observed when relating the UV–vis and the NIR spectra data. The highest correlation values (R2), were observed when HRP was treated at 30 °C–0.1 mg/mL - 200x (R2 0.9930) and 45 °C–100x–0.2 mg/mL (R2 0.9876). The excellent correlation coefficient values obtained show that NIR can be a great alternative to UV–vis spectroscopy, which allows in situ analysis of biocatalytic reactions.

During the crude oil production, stable water-in-oil (W/O) emulsions are generally found along the pipeline between the reservoir and surface facilities. The main objective of this work is discussing about the influence of the salinity (with NaCl at 0, 50, and 100 g·L–1), pH (2, 6, and 10 values), and water content (variations between 8% and 65%) upon the rheological behavior of water-in-crude oil emulsions. Tests including the rotational and oscillatory rheology for assessment of profiles of viscosity, elastic and viscous modulus for the different cases were performed. Semi-theoretical models and available empirical literature models have been successfully used to fit the rheological data, enabling a better understanding of the interactions between the constituents of the samples at a colloidal level. Results presented here show that the emulsion loss modulus calculated from bulk rheological tests does not respond differently for acid, quasi-isoelectric point and alkaline aqueous phase; this modulus also...

This study aimed at investigating flaxseed (Linnum usitatissimum) oil extraction using subcritical propane. Extractions were performed in a laboratory scale unit at temperature (20–60 °C) and pressure (80–120 bar) experimental conditions. Subcritical extraction process kinetic aspects evaluation was performed using four mathematical models found in the literature. The subcritical propane process successfully extracted Omega 3-6-9 fatty acids presenting good yielding in the experimental conditions studied. Physical characterization for commercial and subcritical propane extraction oils presented 1.477 and 1.473 refractive indexes at 40 °C, respectively. The oil extracted using subcritical propane presented free fatty acid contents lower than commercial oil (0.95% wt vs 1.37% wt). The adjusted parameters models presented good fitting with the experimental data under the investigated conditions.

Caseous Lymphadenitis (CLA) is a chronic disease that affects also small ruminants. CLA is caused by Corynebacterium pseudotuberculosis and is responsible for high economic losses due to the formation of superficial and visceral granulomas, the latter is considered as asymptomatic CLA causing high levels of dissemination. Several vaccination strategies, in which the use of synthetic peptides stands out. Thus, this work aimed to evaluate the protective potential of peptide vaccines designed to determine the immunodominant epitopes of CP40 against CLA in mice. The animals were divided into eight groups separated in controls (G1—PBS, G2—Saponin and G9—rCP40) and experimental (G3—pep1, G4- pep2, G5-pep3, G6-pep4, G7-pep5 and G8-pep6), these were vaccinated on days 0 and 15 by a subcutaneous route. 60 days after the first immunization, all animals were challenged with C. pseudotuberculosis. On days 0, 15, 60, and 120 after the first immunization, blood samples were taken to measure immunoglobulins. On the same day of the challenge, the splenocytes were isolated and assayed for the production of IL-2, IL-4, IL-6, IFN-γ, TNF-α, IL-17, and IL-10. After vaccinations, the animals were challenged and all of them were affected by the disease which led to their death. The G6 and G8 groups provided 10% protection and the G7 provided 20%. The G3 and G4 groups provided 30% and 40% protection respectively. The peptides showed the production of Total IgG antibodies and cytokines (IL-2, IL-4, IL-6, IFN-γ, and TNF-α), indicating a possible activation of the Th1 type response. However, groups G3, G5, G6, and G8 showed production of IL-17. None of the study groups showed IL-10 production. The immunogenicity of the peptides was not enough to protect these animals and it is believed that the use of adjuvants based on PAMPs may improve the immune response offered by these peptides.

Strontium-based injection water for enhanced oil recovery has been neglected due to the low solubility of the cation in water. However, challenging reservoirs like those in the Brazilian pre-salt region demand non-conventional solutions to improve oil production. This work shows for the first time that the strontium cation in low salinity water solutions shall be henceforth considered as a potential component in the development of enhanced/improved oil recovery (EOR/IOR) studies. Acidic and non-acidic model oils and real crude oils from Brazilian post-salt and pre-salt fields were used for this study. The oil/brine interfacial tension and viscoelastic properties of the interfacial films were measured by an ascendant drop tensiometer. The results showed that strontium presents the highest interfacial activity among the other alkaline-earth metals. Also, the strontium-based low salinity water produced the most elastic interfacial film, which is desired for the improvement of oil volumetric sweeping promoted by water flooding. Nonetheless, it is worth highlighting that further studies including core flooding experiments must be performed to assess the strontium effect on the crude oil outflow through reservoir pores as well as the influence of water/oil/rock interactions upon it.

During petroleum production and refining, water-in-crude oil emulsions are formed in a desirable or undesirable fashion. However, for economic and operational reasons it is necessary to separate water from oil. In order to present an alternative to the currently available techniques used to solve such task, this study aims to analyze the influence of microwave application modes (multimode and single mode) on the breaking efficiency of a synthetic water-in-crude oil emulsion. In both heating modes, it was observed that the water content, temperature, and total applied energy are preponderant parameters regarding obtain higher efficiencies. The single mode heating required less energy to reach the same temperature and/or demulsification efficiency while the multimode provided better reproducibility. The power dissipation and, consequently, the microwave heating efficiency was dependent on the heating temperature and the emulsion water content. Furthermore, it was noticed that the presence of chemical additives tends to minimize any effect of irradiation mode on demulsification efficiency at temperatures above the 120 °C.

The competing acid catalyzed reactions of fumaric acid (F) isomerization to form maleic acid (Mx) (reaction R1), and the hydration of F to malic acid (M) (reaction R2) were investigated under microwave heating. The kinetic experiments were performed in a sealed microwave-irradiated batch reactor operated at pressures between 615 and 1715 kPa, in the temperature range from 433 to 478 K, and for reaction times up to 21,600 s. Hydrochloric acid at three different concentrations (C H = 0.65, 1.30 and 1.94 M) was used as the catalyst. The concentrations of F, Mx and M were periodically determined by HPLC analyses. The Arrhenius parameters for the forward rate constants of the reactions R1 and R2 were tuned on the experimental data of species concentrations (k 10 = 5.63 ± 0.04 M−1 s−1, E a1/R = 4837 ± 121 K, k 20 = (6.9 ± 0.3) × 107 M−2 s−1, E a2/R = 13,532 ± 212 K). The tuning procedure involved the Simplex method of optimization, and a kinetic model represented by a system of four ordinary differential equations from material balances on species F, Mx, M and HCl. The model was able to reproduce the variation in species concentrations with time for all experimental conditions investigated, just with a partial set of the currently obtained data used to adjust the model parameters (C H = 0.65 M and 1.94 M). The current results at C H of 1.30 M and analogous data from the literature under quite different reaction conditions (e.g.; C H = 0.97 M, non-isothermal reactor externally heated with glycerol) confirm the reliability of the modeling approach. The catalyst concentration had the expected significant effect on the reaction rates, but the influence of microwave irradiation on the kinetics of the conversion of F and on the selectivity of M was small.

The possibility of producing new compounds that combine organic and inorganic materials for improved properties has become increasingly attractive to material science research. The synthesis of organic-inorganic hybrid materials, such as silica modified with an ionic liquid, is an emerging alternative, because the porous silica matrix is already used in several chemical and materials science fields, and ionic liquids have advantageous characteristics compared to other organic compounds. However, the synthesis of hybrid materials involves long reaction times and high temperatures. To overcome this problem, the synthesis of these materials assisted by microwave irradiation has been tested, because is a simple and efficient alternative that reduces reaction time. Some organic synthesis reactions assisted by microwaves have higher reaction rates due to thermal effects, related to specific molecular interactions of microwaves with the material. So, the purpose of this work was to synthesize silica modified with the ionic liquid 1-methylimidazolium chloride using conventional heating and microwave irradiation, as well as to characterize and compare the materials synthesized in both methodologies. After synthesizing the organic-inorganic hybrid material by microwave irradiation, it was observed that it reduced synthesis time and improved its textural properties and chemical composition, when compared to material synthesized with conventional heating.

Thermochemical treatments are traditionally employed to perform the separation between the oil and water phases the petroleum industry. The chemical agents have the function of reducing the barrier rigidity formed by natural surfactants present in the emulsion, thus favoring destabilization. The main objective of this study was to analyze the viscoelastic properties of samples composed by water and a crude oil with the addition of distinct ionic liquids. The methodology used to obtain the interfacial properties was the drop pendant technique. The results showed that the addition of the ionic liquids induced a reduction in the interfacial elasticity and an increase in the compressibility of interfacial films. It was also observed that an enhancement in the alkyl chain length has a positive effect on changing the interfacial properties. The ionic liquid with highest alkyl chain length investigated ([C12min]+[NTf2]-) showed ability to produce the more elastic films for the crude oil investigated.

The dilatational rheological interfacial properties are important in colloidal systems due to the possibility of studying changes in the interfacial tension because of interface relaxation and diffusion. Information on these properties enables analyses on the interfacial activity and mechanical behavior of surfactants in the interfaces for different colloidal systems such as petroleum emulsions. The determination of elastic modulus is crucial for characterizing the interfacial behavior of films containing asphaltenes at interfaces. In this study, the pendant drop tensiometry technique was used to describe the rheological interfacial properties of asphaltenes extracted from two Brazilian oils at toluene/water and heptol (heptane + toluene)/water interfaces under varying proportions of organic solvents (1:1 and 1.5:1) and asphaltene concentrations. The applicability of adsorption isotherm models for involving Gibbs theory and Langmuir equation was investigated for the systems studied. For systems containing...

The asphaltene precipitation and deposition cause severe operational, economic, and environmental problems to the petroleum industry in all of its streams, such as pipe clogging, emulsion stabilization, and incrustation in separators. It is induced by temperature, pressure, and composition changes at crude oil production and refinement. The crude oil incompatibility is the main reason for asphaltene precipitation at refinery plants. Although it has been the subject of studies for the last 50 years, there is still a lack of robust and reliable tools that can detect and monitor the asphaltene precipitation online. In this scenario, the present work aims to use near-infrared spectroscopy to analyze the oil compatibility regarding asphaltene stability as well as to study the influences of pressure, temperature, and composition variation at desalter conditions. For this, a near-infrared spectrometer equipped with a transflectance probe connected to a variable volume high-pressure cell was used. The results sho...

Starch polymer matrices were developed with the incorporation of 1% clove essential oil (EO) (Syzygium aromaticum) aiming for use as active packaging for sausages. At the concentration of 1% EO in the polymer matrix, it showed exponential behavior with respect to oil release over 30 days, with faster release in the beginning and a tendency towards a reduction in release velocity over time. The presence of OE in the biofilm led to significant differences versus the control in terms of aroma and flavor parameters. It was found that EO had an antioxidant effect in sausages with a significant difference between treatments with respect to TBA (thiobarbituric acid) values at the end of a 15 day period of refrigerated storage. There were no significant variations in pH and Aw among treatments during the evaluated period. A significant negative correlation (−0.78) between brightness (L*) and the lipid oxidation of the products was observed.