Brazilian Journal of Chemical Engineering最新文献

Pesticides are chemical compounds widely used in crop pest control, ensuring high productivity and product quality control. However, pesticides are toxic and can be bioaccumulative. Their excessive use causes environmental and health impacts. In this study, the potential of glow discharge plasma to degrade diazinon present in water was investigated. For the degradation process, a glow discharge plasma (GDP) system was used to process diazinon at several plasma flow rates (10, 20, and 30 mL/min) and exposure times (10, 20, and 30 min). The degradation levels and the identification of the by-products were analyzed by gas chromatography coupled to mass spectrum (GC-MS). GDP processing efficiently degraded diazinon, reaching a maximum potential degradation of 8.19 ± 0.92 mg/L, sufficient to bring diazinon-contaminated waters to safe levels. Two parallel degradation routes were proposed for diazinon degradation by cold plasma.

In this work, the degradation of the fast green dye FCF (FG) by means of photocatalysis under natural solar and UVC radiation was studied. The following degradation parameters were evaluated: catalyst type, catalyst dosage, initial dye concentration and pH. Phytotoxicity evaluation was also carried out using Lactuca sativa seeds. ZnO promoted better degradation rates in both radiations, under the best experimental conditions (0.06 g of catalyst, 10 mg L⁻¹ of FG and pH = 6). A generalist kinetic model was developed in order to allow its broad use in a wide range of photodegradation systems. The developed kinetic model was able to fit to the total set of generated data with a coefficient of determination R² = 0.95. The phytotoxicity tests showed an increase in the relative growth of the roots after treatment, indicating a reduction in toxicity of the solution and the efficiency of the process.

One of the main promises of Industry 4.0 is the incorporation of computational intelligence techniques in industrial process control. For the chemical industry, the efficiency of the control strategy can reduce the production of effluents and the consumption of raw materials and energy. A possible, although currently underutilized approach is reinforcement learning (RL), which can be used to optimize many sequential decision making processes through training. This work used Van de Vusse kinetics as an evaluation environment for controllers based on reinforcement learning and comparison with conventional solutions like non-linear model predictive control (NMPC). These kinetics contain characteristics that make it difficult for classic controllers such as PID to handle, such as its non-linearity and inversion point. The investigated algorithms showed excellent results for this notable chemical process control benchmark. This study was divided into two experiments: setpoint change and operation around the inversion point. The former showed the ability of RL controllers to adjust the controlled variable and simultaneously maximize production. The latter revealed the excellent management capability of the reinforcement learning algorithms and NMPC at the inversion point. In this study, the RL algorithms performed similar to NMPC but with lower computational cost after training.

Mixed metal oxide-based nanocomposites (NCs) have remained broadly used for photocatalysis-facilitated elimination of harmful substances from the aquatic ecosystem. Nowadays, searching for an improved photocatalyst looks plentiful; metal oxide-based materials have begun to emerge from studies. In the present work, the use of ZnO/NiO NCs as photocatalytic treatment of wastewater utilizing oxides of metals as photocatalysts has become a subject of major concern. The way of coupling with other semiconductors for improved photodegradation in the presence of UV-visible light. NCs were mainly characterized by XRD, FT-IR, UV-DRS, morphological studies such as SEM and TEM, and elemental composition by EDAX, which all affirmed the effective synthesis of NCs. For instance, ZnO/NiO NCs having a bandgap of about 3.11 eV achieved outstanding degradation activity toward 100% photodegradation of methylene blue (MB) within a short period of time. Further, prepared ZnO/NiO NCs have excellent antibacterial activity against both Gram-negative and Gram-positive bacteria. This behavior is primarily caused by the accumulation of ZnO/NiO NCs on the bacteria’s surface, which results in cytotoxic bacteria and a relatively increased ZnO, resulting in cell death. Also, ZnO/NiO NCs exhibit essential, harmless effects on human red blood cells and their intervention with the action of clotting on both PPP and PRP in human erythrocytes. As an outcome, the studies have shown that Phyllanthus Niruri (L) mediated synthesis by combustion methods performs well as a good capping agent to synthesize ZnO/NiO NCs with important multi-disciplinary applications.

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Heparin is a well-known substance commonly introduced in the bloodstream in many medical procedures to avoid thrombogenicity. Polymer membranes used for biomedical applications, such as in hemodialysis and blood oxygenators, must also have good antithrombogenic and biocompatibility characteristics. Recently developed polyetherimide/polyvinylpyrrolidone (PEI/PVP) hollow fiber membranes showed good potential as an alternative to clinically available membranes, as evaluated by the transport properties of blood-targeted molecules relevant in the treatment of patients with renal chronic diseases. Aiming at improving the hemocompatibility of these membranes, the incorporation of heparin onto their surface was sought as a promising attempt to achieve this goal. In this work, flat sheet PEI/ PVP membranes were prepared by the phase inversion technique and were functionalized through the covalent grafting of heparin. Characterization included the follow-up of hydrophilicity, protein adsorption, prothrombin time (PT), activated partial thromboplastin time (aPTT), hemolysis occurrence, platelet adhesion, and complement system activation. The results showed that heparinization resulted in more hydrophilic membranes (contact angle reduced from 76.5° to 58.5°) and in the reduction of protein adsorption by more than 50%. In contact with human blood, these membranes reduced the occurrence of platelet adhesion, increased aPTT from 34 to 46 s, and did not lead to complement system activation. Such PEI/PVP membranes have therefore remarkable antithrombogenic and biocompatibility characteristics, which are highly desired for use in biomedical applications such as hemodialysis filters.

A spinning disk reactor (SDR) was applied and tested successfully for precipitated calcium carbonate particles synthesis in liquid–liquid system which is poorly understood in literature. The proposed SDR reactor consists of a spinning disk rotating at 4000–16,000 rpm. The proposed SDR resulted in a high local supersaturation ratio due to the intense energy dissipation produced by a high-speed spinning disk. The higher rotational speed of SDR produces calcium carbonate nanoparticles with smaller mean particle sizes and higher aragonite content. At the rotating speed of 15,000 rpm, precipitated calcium carbonate nanoparticles with a size of around 975 nm were produced. In addition, aragonite content increased from 10 to 95 wt% by increasing disk speed from 4000 to 15,000 rpm.

Naphthenate deposits are a major obstacle in ensuring an economic and successful flow in the production and processing of crude oil. The formation of these deposits depends mainly on a specific group of high molecular weight tetrameric acids, sometimes called ARN. Among the challenges of identifying and characterizing the ARN of this complex matrix, we propose the use of a new analysis methodology for identifying these species in oil samples and naphthenate deposits with minimal sample preparation. Such methodology is based on an unconventional approach to the negative-mode electrospray ionization technique, combined with high resolution and precision mass spectrometry. The methodology proved to be promising and advantageous, since it requires a simpler sample preparation and a reduced consumption of reagents and analysis time. With good feasibility of application to identify the nature of deposits and to estimate, in an initial phase, the potential for inorganic scale and the need for oil treatment in production units.

The increasing accumulation of agricultural residues like rice husk (RH) and plantain peels (PP) poses environmental challenges, necessitating efficient waste management strategies. The study explores the potential of anaerobic co-digestion (AcoD) as a sustainable solution, specifically investigating its capacity for biogas generation from these agricultural residues. The primary objective is to determine the optimal substrate mixing ratios (SMRs) to maximize biogas yield. In-depth examination revealed that the highest biogas production reached a significant 2880 mL with a blend of 60% RH and 40% PP (RH60PP40). Additionally, the 80% RH and 20% PP composite (RH80PP20) demonstrated a substantial yield of 1996 mL. However, when plantain peels were used as the major substrate, biogas outputs decreased to 1250 mL and 173 mL for RH40PP60 and RH20PP80, respectively. Synergistic indexes (SI), measuring compatibility, reported values of 1.36 and 1.96 for the most promising samples, underscoring their optimal blending for biogas enhancement. From the perspective of digestate quality, plantain peel-based digestate (PP100D) stood out as a leading biofertilizer candidate due to its enriched nutrient profile. For the kinetic analysis, the logistic model was identified as the most predictive, outperforming the exponential and modified Gompertz models in mapping biogas production dynamics. Conclusively, the study accentuates that strategically optimized anaerobic co-digestion (AcoD) of RH and PP not only amplifies biogas outputs but also presents a viable, sustainable avenue for managing the environmental concerns associated with unchecked agricultural residue accumulation.

Abstract

Microwave assisted glycerol acetylation reactions in a monomode pilot reactor were performed in order to obtain glycerol derivatives as potential biodiesel additives. The reactions were carried out with acetic acid and acetic anhydride using sulfuric acid, pyridine and triethylamine as catalysts. The acetylation reactions yielded a mixture of mono, di and triacetin respectively with short irradiation time and high selectivity to triacetin. Pyridine exhibits 100% of selectivity to triacetin in 30 min of microwave heating with 0.88% (w/w_T) of catalyst concentration. Microwave-heating technology has been demonstrated as an alternative to reach a green chemistry and to this end becomes essential the knowledge of the dielectric properties of the materials involved in microwave heating in order to operate under optimal conditions. Dielectric properties of the pure reagents and during the glycerol acetylation under conventional heating were measured. High loss tangent were obtained for reactions mixtures employing H₂SO₄ and triethylamine and dielectric heating is dominated by ionic conductivity whereas with pyridine the dielectric heating of the reaction mixture is governed by dielectric relaxation process. Physical–chemical analysis of blended biodiesel with triacetin show values for viscosity, flash point, water content, density and acid number in accordance with current international standards. Gaseous emissions analyses of blended biodiesel showed significant reduction of CO emission (50%), CO₂ (25%) and 30% reduction in unburned hydrocarbon (UBHC) and 50% of NOx emissions. The best values were observed in the samples containing 5 and 10% of triacetin.

Graphical abstract

In this work, the Ni/γ-Al₂O₃ (Ni/Al) and Ni/La₂O₃-γ-Al₂O₃ (Ni/La-Al) catalysts were synthesized using the all-in-one method and applied to dry methane reforming, with the aim of minimizing the effects of deactivation through the use of La and the application of monoliths. The characterization showed a smaller Ni crystallite size for the catalyst promoted by La, which was associated with better dispersion of its active phase. The monoliths showed a conversion rate around 15% higher than that of the powdered catalysts. By studying the deactivation of the monoliths and applying residual activity deactivation models (DMRA), it was possible to verify a fit with R² greater than 0.90 and RMSE values below 5%, with the model predicted and adjusted to the residual activity region. In addition, the highest and lowest deactivation of the structured systems was identified for WHSV values of 40 and 20 L h⁻¹ g⁻¹_cat, respectively. Finally, the regeneration of the catalysts with CO₂ proved to be superior to that with H₂, with a regeneration rate of 90% in the first two cycles.