Brazilian Journal of Chemical Engineering最新文献

Decades of heavy reliance on petroleum refineries for energy have led to perpetual environmental pollution. These emissions include sulfur oxides, nitrogen oxides, carbon monoxide, and C1–C4 light hydrocarbons. Researchers worldwide strive to convert these pollutants into value-added products using catalysts. The current review provides a comprehensive overview of valorization of C4 hydrocarbons into value added chemicals, including methacrolein, methacrylic acid, or methyl methacrylate using a green solid catalyst, Keggin-type heteropolyacids. In this review, structures and properties related to catalytic activities are discussed, with the focus on the advancements of Keggin-type heteropolyacids. The influencing factors of the process design are then discussed and succeeded by mechanistic pathways. It is a timely review to place emphasis on sustainable and green chemistry resolution, meanwhile, advocating Sustainable Development Goals No. 8 Affordable and Clean Energy and No. 12 Responsible Consumption and Production.

In this work, we present a pioneering study about the application of blue light-emitting diodes (LED) in the submerged cultivation of the diazotrophic bacterium Ensifer meliloti SEMIA 135. We hypothesize that applying blue light can modify the physiological parameters of cultivation, increasing extracellular polymeric substances (EPS) production and improving its antioxidant activity. Firstly, blue LED was applied during all 96 h of cultivation, which promoted higher biomass concentration and specific growth rates than the one without illumination. However, a clear influence of blue light intensity was not observed in the production of polymeric substances. A novel strategy was proposed, consisting of the application of blue LED only up to the first 24 h of cultivation (exponential phase). In such conditions, cultures exposed to 50 μmol m⁻² s⁻¹ showed a maximum EPS production (4.79 g L⁻¹) at 72 h, while the control without illumination showed 3.17 g L⁻¹ at 96 h. Finally, the effects of the EPS produced through cultivation under blue LED incidence were evaluated regarding antioxidant activity by capturing DPPH^• and ABTS^• radicals and reducing power. A dose-dependent behavior was observed for all antioxidant assays performed. However, only DPPH^• radical antioxidant assay showed a positive influence when blue LED at 50 μmol m⁻² s⁻¹ was applied. These results showed that cultivation associated with blue LED could improve EPS synthesis and their antioxidant activity. The results expand the opportunities for EPS applications as a thickener, stabilizer, emulsifier, or antioxidant agent and demonstrate the advantages of high productivity associated with an eco-friendly approach.

Solubility is one of the most important physicochemical properties, because it is related to some industrial processes such as: formulation, preformulation, purification and quantification. The experimental determination of solubility requires rigorous processes that involve a significant amount of resources. In this context, mathematical models allow estimating solubility under conditions different from the experimental ones from a limited number of data. The objective of this research was to evaluate the pertinence of 10 mathematical models (Extended Hildebrand, van’t Hoff, Two-parameter Weibull, Buchowski–Ksiazczak (lambda h), van’t Hoff-Yaws, Apelblat, Wilson, NRTL, Modified Wilson and van’t Hoff-Modified Wilson) in the calculation of the solubility of isoniazid in PEG 200 (1) + Water (2) cosolvent mixtures, the parameters of each model were calculated using Python, Pandas and the NumPy and SciPy library. Once each model was evaluated, two models were defined as the best alternatives based on their predictive power and mathematical simplicity. Thus, the van’t Hoff and Modified Wilson models were combined to obtain an equation that allows the calculation of solubility as a function of temperature and cosolvent composition, obtaining MRD% less than 3.0. In conclusion, mathematical models represent a good prediction tool being a potential alternative in relation to the optimization of some industrial processes related to solubility.

Textile industries produce extensive dye waste which if discharged into the freshwater bodies, can result in contamination and toxic effects on humans as well as ecosystem. Rhodamine B (RhB) is one of the major pollutants in textile wastewater and requires considerable attention for its remediation. The present study focuses on developing a novel design of a swirling flow photolytic oxidation reactor for large volume treatment of RhB dye. Degradation of Rh-B was studied at varying initial concentrations, variable quantities of Fenton’s reagent and hydrogen peroxide as additives, individually and in combination to achieve maximum efficacy. Further, the treatment efficacy of the reactor was optimized using surface response method based on Doehlert matrix with initial dye concentration (ppm), Fenton’s reagent (g) and pH as independent factors optimized to achieve maximum RhB degradation (%). The article also describes in detail about the design considerations and advantages of swirling flow photolytic reactor over classical UV/Fenton batch reactor setup. It highlights advantages of the design modifications along with catalytic oxidative reactions to achieve maximum dye degradation. The swirling flow photocatalytic reactor showed promising results especially for large volume degradation of RhB dye, while degradation percentage was significantly improved using the optimized parameters. When compared to the individual UV irradiation (25% degradation), the approach involving the combination i.e. UV with Fenton in the modified reactor, demonstrated degradation of RhB as high as up to 100%.

Diesel oil is one of the main fuels applied in the transport industry. With a view to contributing to sustainable energy development, the use of mixtures containing diesel, biodiesel and alcohols is an attractive option. This research aims to develop and characterize new fuel formulations with DieselB10/Butanol/Methanol (DBM) and DieselB10/Butanol/Ethanol (DBE) using a combined approach of experimentation in diesel engines and advanced thermodynamic modeling. The formulations were determined based on equilibrium diagrams (25 °C) and submitted to density tests (ASTM D4052), kinematic and dynamic viscosities (ASTM D7042), corrosiveness to copper (ASTM D130), fluidity point (ASTM D97), cloud point (ASTM D2500), cold filter plugging point (ASTM D6371) and vapor pressure (ASTM D6378), which showed 100% compliance with National Petroleum, Natural Gas and Biofuels Agency (ANP) specifications. Next, the mixtures were used to construct diesel cycle engine power curves (ABNT – NBR ISO 1585). The miscibility curves indicated that the DBE system, which uses ethanol, has a smaller biphasic region compared to the DBM system, due to the lower polarity of ethanol. Thermodynamic models UNIQUAC (Universal Quasichemical) and NRTL (Non Random Two-Liquid) were employed, with UNIQUAC being more accurate (RMSD—Root Mean Square Deviation—of 0.34%) compared to NRTL (RMSD of 2.25%). The addition of alcohols increased the cloud point and vapor pressure while reducing viscosity and density. The formulations met ANP standards and did not present a corrosion risk. Engine tests showed that the DB formulation had lower hourly consumption and higher efficiency compared to DieselB10, with increased specific consumption due to the lower calorific value of the alcohols.

The N-[3-(Dimethylamino)propyl] hexadecanamide (DMPH) molecule is an important intermediate for synthesizing amphoteric and quaternary ammonium surfactants. Despite its importance for the household and personal care sectors, little to no information about its enthalpy of formation is found in the NIST database or literature, which hinders many industrial operations, especially its chemical production, by consuming much more energy than necessary. In this work, we present a first estimative of N-[3-(Dimethylamino)propyl] hexadecanamide's standard enthalpy of formation with a simple procedure that can be used to obtain similar parameters in chemical industry laboratories. The enthalpy estimative was obtained by reacting palmitic acid and dimethylaminopropylamine (DMAPA), yielding the desired compound. Hess's law was used to determine the enthalpy of the reaction through the heat associated with the extent of the reaction. The reagents were contacted in a simple calorimeter at room temperature (diluted with acetone) and 373.15 K (without acetone). The extent of the reaction was obtained by quantitative determination of the reaction medium in gas chromatography. The room temperature experiment led to an insignificant extent of reaction, which generated an unreliable result for the DMPH enthalpy of formation. In contrast, at 373.15 K, the estimated standard enthalpy of the reaction was adequately calculated, leading to an enthalpy of formation of − 753.86 ± 84.83 kJ/mol for the N-[3-(Dimethylamino)propyl] hexadecanamide. With this simple procedure, the heat consumption of an industrial reactor can be calculated with more precision, yielding economic and environmental benefits.

Spent catalysts from fluid catalytic cracking have been a new opportunity for recovering metallic species from secondary sources, avoiding species waste, and also contributing to the circular economy, allowing the manufacture of new products. Regarding the techniques used, electrokinetic remediation coupled with selective precipitation arises as an appropriate alternative in the removal of lanthanum from refinery catalysts. To that end, the present work aimed to evaluate the recovery of lanthanum by selective precipitation using the effluent obtained from the electrokinetic remediation process of the spent catalyst from the fluid catalytic cracking process. Subsequently, some precipitation experiments were conducted in different temperatures of ammonium oxalate solutions to foster lanthanum oxalate precipitation, and the kinetic precipitation parameters were also obtained. The extraction of lanthanum ions from electroremediation resulted in 88.43%. Moreover, the best temperature to obtain lanthanum oxalate occurred at 25 °C, recovering 99.85% of the product, with an energy consumption of 100.19 W h g⁻¹. The results indicated that the precipitation reaction fitted a first-order model, presenting an activation energy of 58.3 kJ mol⁻¹. In light of these results, the coupling of electrokinetic remediation and selective precipitation techniques presented themselves as a suitable alternative to the recovery of metallic species from spent catalysts.

Polysaccharides from Lentinus tigrinus are promising due to their properties that allow biotechnological applications in several areas. This study aimed to optimize the extraction of polysaccharides from the cell wall of L. tigrinus CCMB 553, in addition to characterizing it, performing antioxidant activity assays and evaluating the capacity to inhibit α-amylase in vitro. The optimal extraction conditions found were pH 13, temperature 90 °C and time 180 min. The Fourier Transform Infrared Spectroscopy indicated signals characteristic of polysaccharide and Gas Chromatography coupled with Mass Spectrometry demonstrated a polysaccharide composed of monomeric units such as galactoses, glycopyranose and mannopyranose. The in vitro antioxidant assays showed the potential of the polysaccharide in ABTS⁺, DPPH and hydroxyl radical elimination. The polysaccharide demonstrated the ability to inhibit α-amylase in vitro with a concentration of 0.1 mg mL⁻¹. The results suggest that L. tigrinus polysaccharide is a promising source for potential pharmaceutical products.

Pyrolysis has been essential in the context of renewable energies, offering an innovative approach for biomass and solid waste valorization. Therefore, mathematical models that can represent its phenomena are of fundamental importance in understanding the reaction progression and optimizing the process. In this sense, we sought to analyze the capability of single-particle models in representing the yields of pyrolysis reactions in fluidized beds. To describe the behavior and interaction between the phases, we utilized an Eulerian–Lagrangian CFD modeling approach, solving the continuity, momentum, energy, species, and turbulence equations using OpenFOAM. We adopted the multicomponent and multi-stage model to describe the kinetics of pyrolysis in three different types of biomass. The numerical results obtained for the yields of pyrolysis reactions using the proposed modeling approach showed good agreement with the experimental data reported in the literature. We observed a maximum discrepancy of 3% in the study of pure cellulose reaction, 5.14% in red oak, and 0.56% in sugarcane bagasse. Therefore, we concluded that the single-particle model accurately represents the yields of pyrolysis reactions, making it suitable for estimating yields and conversion rates, providing valuable insights into pyrolysis behavior, and aiding in developing projects and optimization studies.

The core-shell structured nanomaterial of MgCo₂O₄@MnO₂ on nickel foam (MCMNA/NF) was synthesized via a two-step hydrothermal method. It can be used as a self-supported electrode, which was constructed to an electrochemical sensor for sensitive measurement of glucose. The core-shell structure with a MnO₂ shell significantly enhances the material’s specific surface area and accelerates the electron transport process. Electrochemical catalytic oxidation tests were conducted on core-shell structured MCMNA/NF nanocomposite as a working electrode. The sensitivity is determined to be 9.37 μA·mM⁻¹·cm⁻² and the detection limit is 0.02 mM. These test results demonstrate that the material exhibits excellent stability and selectivity as a glucose sensor. The synergistic effect of MgCo₂O₄ and MnO₂ can effectively promote the application performance of the electrode materials. The MgCo₂O₄@MnO₂ glucose sensor material also exhibits exceptional resistance to interference, demonstrating no interference from Urea, Citric acid (CA), Ascorbic acid (AA), or specific inorganic salts during blood glucose detection.

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