Search Results (51)

Actions related to reducing CO₂ emissions have led to the development of technologies using raw materials in the form of broadly understood biomass as CO₂-neutral fuels. There has been a rapid development of pyrolysis processes (carbonization, dry distillation) of various types of biomass toward the production of biochar for industrial applications. Particularly high hopes are associated with the use of biochar as a substitute for fossil fuel in energy-intensive sectors of the economy, especially the metallurgical and steel industries. This paper characterizes the current state and potential for biochar application, using the iron and steel industry as a case study. The analysis focuses primarily on the characteristics of biochar production and its industrial application potential. The characterization includes the diversity of biomass feedstocks, processing methods, and reactor types, the influence of operational parameters on biochar yield, as well as the properties and applications of biochar. As part of the analysis of biomass use potential in the iron and steel industry, the study reviews the current levels of coal substitution achieved at the laboratory scale and presents examples of biochar implementation in existing industrial facilities. In addition, key factors limiting the feasibility of coal substitution in the iron and steel industry are identified. The summary includes the main directions for further research aimed at increasing the use of biochar in industry. Full article

With the rapid development of the livestock farming industry, the treatment of livestock farming wastewater has become increasingly important. The microbial-algal biofilm method has gained widespread attention for cattle wastewater treatment owing to its non-toxic nature, resistance to shock loading, and high treatment efficiency. In this study, three types of substrates—polyurethane sponge, ceramic material, and moving bed biofilm reactor media—were evaluated. The formation of biofilms was assessed through variations in chlorophyll content, microscopic observations, and measurements of biofilm dry weight and attachment rate. Biofilm characterization on the different substrates was conducted via Fourier transform infrared spectroscopy, confocal laser scanning microscopy, and scanning electron microscopy. The results demonstrated that polyurethane sponge was the most effective substrate. Furthermore, a single-factor experiment was conducted to optimize the cultivation conditions for the microbial-algal biofilms and identify the optimal parameters based on the ability of the biofilm to remove COD, TN, TP, and NH₄⁺-N. The optimal conditions were as follows: an illumination intensity of 8000 lux, red light, a temperature of 20 °C, a pH of 7, and an aeration intensity of 8 L/min. Under these conditions, the pollutant removal rates were exceptionally high: ~73.4% for COD, 51.8% for TP, 57.0% for TN, and 75.1% for NH₄⁺-N. Full article

The purpose of this study is to reveal the characteristics of a Pd/Cu membrane and Ni/Cr catalyst adopted in a biogas dry reforming (BDR) membrane reactor by the numerical simulation procedure. The commercial software COMSOL Multiphysics ver. 6.2 was adopted in the numerical simulation. COMSOL is one type of commercial software that can solve multiphysics phenomena, i.e., chemical reaction, fluid dynamics, heat transfer, etc. The impact of the initial reaction temperature and the thickness of the Pd/Cu membrane on the performance of the BDR membrane reactor using an Ni/Cr catalyst is also investigated. The initial reaction temperatures adopted were 400 °C, 500 °C, and 600 °C, and the thicknesses of the Pd/Cu membrane were varied at 20 μm, 40 μm, and 60 μm. It was discovered that when the initial reaction temperature was raised, the molar concentration of H₂ increased while the molar concentrations of CH₄ and CO₂ decreased. Because the penetration resistance of the Pd/Cu membrane decreased with the decrease in the thickness of the Pd/Cu membrane, the molar concentrations of H₂ remaining in the Pd/Cu membrane and sweep chamber rose with the decrease in the thickness of the Pd/Cu membrane. Full article

In this study, plasma-activated water (PAW) was generated using a large-volume (5 L) plasma reactor with a quasi-stationary, water-cathode glow-type discharge in atmospheric pressure air. Tap water was activated up to 75 min. PAW exhibited high concentrations of long-lived reactive nitrogen species (RNSs), reaching 8 mM, which is between 4 and 26 times higher than those reported in previous studies. The reactor reached an RNS synthesis efficiency of 61 nmol/J and an RNS production rate of 526 μmol/min, both among the highest reported. PAW was evaluated on tomato and bell pepper. Seedling emergence was determined in a nutrient-free substrate. To assess plant growth, seedlings were transplanted into pots filled with either nitrogen-free or nutrient-rich substrate. PAW-irrigation significantly promoted seedling emergence and leaf expansion, especially in tomato plants. The plant growth-stimulating effects of PAW were more pronounced in nitrogen-free substrate: fresh weight of tomato and bell pepper increased up to 13.1-fold and 2.6-fold, respectively. In contrast, the effect on the nutrient-rich substrate was negligible. Tomato plants grown in the nitrogen-free substrate and irrigated with 75-min PAW reached a dry weight comparable to those grown in nutrient-rich substrate. PAW irrigation did not induce oxidative stress, as confirmed by malondialdehyde (MDA) levels and antioxidant enzyme activity. Full article

Dry-type air-core reactors (DAR) are critical components in power systems but are prone to inter-turn short circuit faults which interrupt the symmetry of the winding structure. Inspired by the online detection of transformer winding deformation, the V-I method has been adapted to diagnose short circuit faults in reactors. However, the diagnostic criteria and thresholds of V-I method remain unclear. This paper presents a novel method for determining the threshold for detecting inter-turn short circuit faults in DAR, integrating V-I analysis with machine learning techniques. Specifically, Gradient Boosting Regression (GBR) is used to compute a standard diagnostic criterion value, and curve fitting is also used to define the threshold for identifying inter-turn short circuit faults. The experimental results demonstrate that this method effectively identifies fault conditions in DAR. Full article

Background: The callus cultures from the fronds of the lycophyte Phlegmariurus taxifolius produce the huperzine A (HupA) alkaloid, which is used in Alzheimer’s disease treatment. This study aimed to establish the growth kinetics and HupA production by the newly HupS21 cell line grown in 250 mL flasks and in a 2 L airlift bioreactor. Methods: Batch-type kinetics were carried out for 60 days in 250 mL flasks and for 20 days in a 2 L airlift bioreactor. Measurements of dry weight (DW), specific growth rate (μ), doubling time (dt), pH, carbohydrate consumption, and HupA quantification were performed. The acetylcholinesterase (AChE) inhibitory assay of the HupS21 alkaloidal extract was determined. Results: The 250 mL flasks kinetic reached a maximum cell growth of 8.17 g/L DW, with a μ of 0.045 day⁻¹ and a dt of 15.40 days. The maximum HupA production was of 2.03 μg/g DW at day 45. In the 2 L airlift reactor, a maximum growth of 16.70 g/L DW, a μ of 0.062 day⁻¹, a dt of 11.20 days, and HupA production of 2.48 μg/g DW at day 15 were obtained. The alkaloidal extract from the HupS21 cell line at 100 μg/mL showed an AChE inhibitory activity of 85.6 ± 1.27%. Conclusions: The airlift reactor outperformed the flask cultures in maximum cell growth, specific growth rate, doubling time, and HupA production. To our knowledge, this research is the first report on the establishment of suspension cell cultures of P. taxifolius in shaken flasks and in an airlift bioreactor, providing a foundation for scaling up HupA production for pharmaceutical use. Full article

Plasma-activated water (PAW) is a sustainable and innovative alternative for agriculture, especially in controlled environments like greenhouses. Tomato and pepper are key horticultural crops worldwide, with a considerable part of their production in greenhouses. This study examined the effects of PAW irrigation on seed germination, plant growth, and oxidative stress in tomato and bell pepper plants. PAW was activated for up to 15 min using a 1 L capacity plasma reactor based on a glow-type discharge in air with water-cathode. The concentration of nitrogen compounds and the energy efficiency of synthesis obtained with the reactor were moderately high (5.4 mM and 60 nmol/J, respectively). The most notable effects of PAW were observed in bell pepper. The germination percentage in bell pepper increased by up to 26%, while no significant effects were found in tomato seeds. PAW irrigation significantly promoted plant growth, with dry weight increasing by up to 61% in bell pepper and 42% in tomato. Lipid peroxidation results showed no oxidative damage in either crop. The biochemical analysis of antioxidant enzymes (catalase, superoxide dismutase, and guaiacol peroxidase) confirmed that plant defense systems responded adequately to PAW irrigation. These results highlight PAW’s potential as an innovative and eco-friendly alternative in agriculture. Full article

Dry-type air-core reactors (DARs) often have inter-turn short circuit (ITSC) faults. However, traditional fault detection methods for DARs generally demonstrate poor timeliness and low sensitivity, and few methods combine intelligent algorithms for objective and accurate diagnosis. Therefore, a novel online diagnosis method for ITSC faults was proposed. First, the “field-circuit” coupling 2D model of reactors was established to simulate the impact of ITSC faults on the characteristics of various state parameters; accordingly, the Lissajous graph was introduced to characterize the short circuit fault. Then, the variation law of the Lissajous graph under different inter-turn fault layers, turns, and degrees was explored to verify the feasibilities of the proposed method. Finally, to achieve rapid diagnosis and fulfill the requirements of edge computing, a lightweight network model named MobileNetV3-Small was used and combined as a classifier to achieve accurate diagnosis of ITSC faults. The results robustly validate that the Lissajous graphical method can significantly reflect ITSC faults through observing the variation in the graph and feature parameters. Furthermore, the MobileNetV3-Small model achieves a diagnostic accuracy of up to 95.91%, which can further enhance the diagnostic accuracy of the ITSC fault degree. Full article

Excessive (carbon dioxide) CO₂ emissions are a primary factor contributing to climate change. As one of the crucial technologies for alleviating CO₂ emissions, carbon capture and utilization (CCU) technology has attracted considerable global attention. Technologies for capturing CO₂ in extreme circumstances are indispensable for regulating CO₂ levels in industrial processes. The unique separation characteristics of the ceramic–carbonate dual-phase (CCDP) membranes are increasingly employed for CO₂ separation at high temperatures due to their outstanding chemical, thermal durability, and mechanical strength. This paper presents an overview of CO₂ capture approaches and materials. It also elaborates on the research progress of three types of CCDP membranes with distinct permeation mechanisms, concentrating on their principles, materials, and structures. Additionally, several typical membrane reactors, such as the dry reforming of methane (DRM) and reverse water–gas shift (RWGS), are discussed to demonstrate how captured CO₂ can function as a soft oxidant, converting feedstocks into valuable products through oxidation pathways designed within a single reactor. Finally, the future challenges and prospects of high-temperature CCDP membrane technologies and their related reactors are proposed. Full article

Coasts are home to one-third of the human population. In the process of energy transition, local biomass and waste resources represent a renewable fuel that can substitute fossil fuels in order to reduce greenhouse gas emissions, hence including marine resources as part of the eligible feedstock for renewable energy production. Gasification regroups different technologies that aim to convert a solid fuel into a useful gas, and has several applications, such as heat production, power generation, and chemical synthesis. Gasification technologies regroup the traditional “dry” processes that use relatively dry fuels, but recent developments have been made with “wet” processes such as hydrothermal gasification, in sub- or supercritical conditions for the water, which can accept wet fuel. This review focuses on scientific articles that performed gasification of marine resources in order to produce a syngas. First, a definition of marine resources is made, followed by the presentation of marine resources studied in the literature. Secondly, this review presents the different types of gasification reactors and their operating conditions, followed by a summary of the different syngas produced with their composition as a performance indicator. Finally, this review exposes the limitations of the current literature and concludes with perspective propositions. Full article

In this paper, we report the growth of high-quality ${\mathrm{In}}_{0.59}{\mathrm{Ga}}_{0.41}\mathrm{As}/{\mathrm{In}}_{0.37}{\mathrm{Al}}_{0.63}\mathrm{As}$ strain-balanced quantum cascade lasers (QCLs) in the low-pressure MOCVD production type multi-wafer planetary reactor addressing, in particular, quality and scaled manufacturing issues. Special attention was given to achieving the sharp interfaces (IFs), by optimizing the growth interruptions time and time of exposure of InAlAs layer to oxygen contamination in the reactor, which all result in extremely narrow IFs width, below 0.5 nm. The lasers were designed for emission at $7.7\mu$m. The active region was based on diagonal two-phonon resonance design with 40 cascade stages. For epitaxial process control, the High Resolution X-Ray Diffraction (HR XRD) and Transmission Electron Microscopy (TEM) were used to characterize the structural quality of the QCL samples. The grown structures were processed into mesa Fabry-Perot lasers using dry etching RIE ICP processing technology. The basic electro-optical characterization of the lasers is provided. We also present results of Green’s function modeling of QCLs and demonstrate the capability of non-equilibrium Green’s function (NEGF) approach for sophisticated, but still computationally effective simulation of laser’s characteristics. The sharpness of the grown IFs was confirmed by direct measurements of their chemical profiles and as well as the agreement between experimental and calculated wavelength obtained for the bandstructure with ideally abrupt (non-graded) IFs. Full article

In this work, the pyrolysis process and the characteristics of biochar produced using a bench-scale fixed-bed reactor and a prototype-scale auger reactor were studied. Residual forest biomass (RFB) from acacia, broom, gorse, and giant reed was used as feedstock. Besides information on pyrolysis characteristics of these specific biomass species from the Iberian Peninsula, new knowledge on the understanding of how results from small-scale reactors can be used to predict the behavior of higher-scale and continuous-operation reactors is offered. Batch pyrolysis was carried out using 40 g of biomass sample in a fixed-bed reactor with a heating rate of 20 °C∙min⁻¹, pyrolysis temperature of 450 and 550 °C, and a residence time of 30 min, while for the continuous process it was used a prototype of an auger reactor with continuous operation with a biomass flow rate up to 1 kg/h, with temperatures of 450 and 550 °C, and a solids residence time of 5 min. The biochar yield was in the range of 0.26 to 0.36 kg/kg biomass dry basis, being similar for both types of reactors and slightly lower when using the auger reactor. The proximate analysis of the biochar shows volatile matter in the range 0.10 to 0.27 kg/kg biochar dry basis, fixed carbon in the range 0.65 to 0.84 kg/kg biochar dry basis, and ash in the range 0.04 to 0.08 kg/kg biochar dry basis. The carbon, oxygen, and hydrogen content of the biochar was in the range of 0.71 to 0.81, 0.09 to 0.22, and 0.02 to 0.03 kg/kg biochar dry basis, respectively. The results show that the up-scaling of the reactor and regime of operation does not have an important influence on the yield and characteristics of the biochar produced. The biochar obtained in the two types of reactors has characteristics appropriate for environmental applications, such as an additive to improve soil properties. It is possible to see that the characteristics of the biochar are influenced by the type of biomass and the conditions and parameters of the process; therefore, it is of major importance to control and know of these conditions, especially when considering upscaling scenarios. Full article

Oak bark is a by-product known for its richness in polyphenols, with tanning substances being particularly interesting for their application in different fields. Vegetable tannins are mostly utilized in the leather sector, but are also widely used as adhesives, in cement plasticizers and for medical and agrochemical applications owing to their natural antimicrobial activity. This study aimed to develop a green and efficient pilot-scale technique for extracting polyphenols from oak bark by ultrasound-assisted extraction (UAE) using a modified Dual-Frequency Reactor (DFR). Different parameters, such as extraction time, temperature, and solvent type (water, sodium hydroxide or sodium sulfite and bisulfite solutions) were investigated for their influence on the total phenolic content (TPC) and the quantity of dry extract. Control experiments by conventional methods were also performed. UAE at 50 °C yielded the highest TPC and dry extract (confirmed by ANOVA analysis, p < 0.05) in just 10 min, suggesting that UAE can be considered an energy- and cost-effective alternative to conventional techniques. The most suitable solvent was found to be a 0.5% sodium hydroxide solution. The molecular profile of the extracts was assessed by FTIR-ATR spectroscopy, revealing typical signals of tannins in all extracts. Furthermore, antimicrobial activity tests demonstrated the complete absence of Gram-positive and Gram-negative bacteria in the extracts, ensuring the suitability of the product for different kinds of application. Full article

Dry-type air-core shunt reactors are integral components in power transmission and distribution networks, designed to control reactive power and enhance system stability. However, inter-turn short-circuit faults (ISCFs) are common occurrences in shunt reactors, which are caused by various factors, including manufacturing defects, insulation degradation, or operational stresses. At the early stage of the ISCFs, the current does not reach a sufficient level to activate the protective equipment. These faults may lead to serious consequences, such as overheating, insulation breakdown, and even catastrophic failures, posing risks to the entire power system. Therefore, developing an effective and reliable detection method for ISCFs at the early stage is paramount. In this paper, a new method named the fault detection factor (FDF) based on equivalent resistance is presented to detect the slight ISCFs in dry-type air-core shunt reactors considering insulation resistance. In addition, the effect of noise signal existence in the monitoring process is taken into account. A moving average filter is adopted to guarantee both the sensitivity and the reliability of the proposed method. Ultimately, the simulation results of the FDF under different conditions are presented, which show the effectiveness and potential of the proposed method in observing and monitoring slight ISCFs. Full article

CO and HCHO are the main pyrolysis gases in long-term running dry-type reactors, and thus the diagnosis of thermal insulation faults inside such devices can be realized by sensing these gases. In this paper, a single Au atom-decorated WS₂ (Au-WS₂) monolayer is proposed as an original sensing material for CO or HCHO detection to evaluate the operation status of dry-type reactors. It was found that the Au atom prefers to be adsorbed at the top of the S atom of the pristine WS₂ monolayer, wherein the binding force is calculated as −3.12 eV. The Au-WS₂ monolayer behaves by chemisorption upon the introduction of CO and HCHO molecules, with the adsorption energies of −0.82 and −1.01 eV, respectively. The charge density difference was used to analyze the charge-transfer and bonding behaviors in the gas adsorptions, and the analysis of density of state as well as band structure indicate gas-sensing mechanisms. As calculated, the sensing responses of the Au-WS₂ monolayer upon CO and HCHO molecule introduction were 58.7% and −74.4%, with recovery times of 0.01 s and 11.86 s, respectively. These findings reveal the favorable potential of the Au-WS₂ monolayer to be a reusable and room-temperature sensing candidate for CO and HCHO detections. Moreover, the work function of the Au-WS₂ monolayer was decreased by 13.0% after the adsorption of CO molecules, while it increased by 1.2% after the adsorption of HCHO molecules, which implies its possibility to be a work-function-based gas sensor for CO detection. This theoretical report paves the way for further investigations into WS₂-based gas sensors in some other fields, and it is our hope that our findings can stimulate more reports on novel gas-sensing materials for application in evaluating the operation conditions of dry-type reactors. Full article