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Showing records 27850 to 27874 of 43292. [First] Page: 1 1111 1112 1113 1114 1115 1116 1117 1118 1119 Last
27850. LAPSE:2023.11284
Research on Assembly Sequence Optimization Classification Method of Remanufacturing Parts Based on Different Precision Levels
February 27, 2023 (v1)
Subject: Energy Systems
Keywords: assembly sequence, combinatorial algorithm, engine, remanufacturing, selection matching
Aiming at resolving the problem of low assembly accuracy and the difficulty of guaranteeing assembly quality of remanufactured parts, an optimization classification method for the assembly sequence of remanufactured parts based on different accuracy levels is proposed. By studying the characteristics of recycled parts, based on the requirement that the quality of remanufactured products not be lower than that of the assembly quality of new products, the classification selection matching constraints of remanufactured parts are determined, and the classification selection matching optimization models of remanufactured parts with different precision levels is established. An algorithm combining particle swarm optimization and a genetic algorithm is proposed to solve the model and obtain the optimal assembly sequence. Taking the remanufacturing assembling of a 1.4 TGDI engine crank and a connecting rod mechanism as an example, the comparison of quality data shows that this method can effec... [more]
27851. LAPSE:2023.11283
Review of CFD-DEM Modeling of Wet Fluidized Bed Granulation and Coating Processes
February 27, 2023 (v1)
Subject: Modelling and Simulations
Keywords: CFD-DEM, coating, fluidized bed, granulation
Wet fluidized bed granulation and coating processes have been widely used in the pharmaceutical and food industries. The complex gas−solid flow coupled with heat and mass transfer in such processes made it hard to form complete control over the apparatuses. To serve better design, scaling-up, and optimization of granulators and coaters, the underlying micro-scale mechanisms must be clarified. Computational fluid dynamics coupled with the discrete element method (CFD-DEM) provides a useful tool to study in-depth the gas-solid hydrodynamics of the granulation and coating processes. This review firstly introduced the fundamental theory of CFD-DEM from governing equations, force calculation, and coupling schemes. Then the application of CFD-DEM in simulating wet fluidized bed granulation and coating was presented. Specifically, the research focus and the role of CFD-DEM in resolving issues were discussed. Finally, the outlook on the development of CFD-DEM in the context of granulation and... [more]
27852. LAPSE:2023.11282
Geometallurgical Detailing of Plant Operation within Open-Pit Strategic Mine Planning
February 27, 2023 (v1)
Subject: Planning & Scheduling
Keywords: geometallurgy, linear programming, metaheuristics, metallurgical plant, open-pit mine planning, Stochastic Optimization
Mineral and metallurgical processing are crucial within the mineral value chain. These processes involve several stages wherein comminution is arguably the most important due to its high energy consumption, and its impact on subsequent extractive processes. Several geological properties of the orebody impact the efficiency of mineral processing and extractive metallurgy; scholars have therefore proposed to deal with the uncertain ore feed in terms of grades and rock types, incorporating operational modes that represent different plant configurations that provide coordinated system-wide responses. Even though these studies offer insights into how mine planning impacts the ore fed into the plant, the simultaneous optimization of mine plan and metallurgical plant design has been limited by the existing stochastic mine planning algorithms, which have only limited support for detailing operational modes. The present work offers to fill this gap for open-pit mines through a computationally e... [more]
27853. LAPSE:2023.11281
Molecular Dynamics Simulation of the Interfacial Structure and Differential Capacitance of [BMI+][PF6−] Ionic Liquids on MoS2 Electrode
February 27, 2023 (v1)
Subject: Modelling and Simulations
Keywords: differential capacitance, electric double-layer structure, ionic liquid, MoS2 electrode, supercapacitor
MoS2 nanomaterials and ionic liquids (ILs) have attracted tremendous interest as the prime electrodes and electrolytes of supercapacitors. However, the corresponding charge storage mechanisms have not yet been clearly understood. Herein, we study the molecular-level energy storage mechanisms of the MoS2 electrode in imidazolium ionic liquid ([BMI+][PF6−]) using molecular dynamics (MD) simulation. The electric double-layer (EDL) structures of MoS2 electrodes in [BMI+][PF6−] electrolytes are comprehensively studied in terms of number density, MD snapshots, separation coefficient, and ion-electrode interaction energy. Based on this, the electric potential and electric field distributions are calculated by integrating Poisson equations. Importantly, a bell-shaped differential capacitance profile is proposed, different from the U-shaped curve from the conventional Gouy−Chapman theory. Especially, it can be well reproduced by the differential charge density curve in the Helmholtz layer. This... [more]
27854. LAPSE:2023.11280
Effect of Environmental Conditions on Strontium Adsorption by Red Soil Colloids in Southern China
February 27, 2023 (v1)
Subject: Environment
Keywords: Adsorption, China, soil colloid, strontium (Sr2+)
The fate of radionuclides in the environment is attracting increased attention. The effect of various environmental effects on the adsorption behavior of the strontium ion (Sr2+) by red soil colloids in Southern China was studied by a series of batch experiments, and the adsorption mechanism was briefly investigated as well. With the increase in the solid−liquid ratio and the concentration of Sr2+, the adsorption efficiency increased gradually. The effect of pH and ionic strength on adsorption was strong, while temperature had little effect. The adsorption data fitted to the Langmuir model indicates that the process is monolayered and homogeneous. The thermodynamic parameters also show that the adsorption of Sr2+ on red soil colloids is a spontaneous and exothermic process. The aim of this work is to gain insight into the role of red soil colloids on the fate of radionuclides in the field.
27855. LAPSE:2023.11279
Base-Level Fluctuation Controls on Migration of Delta Lobes: A Case Study from the Paleogene Shahejie Formation in the Huimin Depression, Bohai Bay Basin, NE China
February 27, 2023 (v1)
Subject: Process Control
Keywords: base level fluctuations, Huimin Depression, lacustrine deltas, Paleogene, sequence stratigraphy
Sandbody distribution patterns and controls are the most important foundation for petroleum exploration and development, particularly in a lacustrine basin with rapid changes in the sedimentary environment. To provide sedimentologists and petroleum geologists around the world with an analogue for sandstone reservoir prediction, the sedimentary facies of the fourth member of the Shahejie Formation (Sha-4 Member) in the Huimin Depression of the Bohai Bay Basin were analyzed, and the sequence stratigraphic framework was established based on characteristics of spontaneous potential logs and lithology. According to the findings of this study, the Sha-4 Member’s sedimentary environment was dominated by delta front and shallow lake facies. Delta front sandbodies were discovered to retrograde before prograding again throughout the established profile. The Sha-4 Member in the Huimin Depression is divided into a third-order sequence (LSC1), which can be further divided into four fourth-order seq... [more]
27856. LAPSE:2023.11278
Special Issue on “Progress in Food Processing in Section Food Processes”
February 27, 2023 (v1)
Subject: Food & Agricultural Processes
Food production is being confronted by numerous difficulties related to sustainability, food quality and security [...]
27857. LAPSE:2023.11277
Effect of Roasting Hass Avocado Kernels on Nutritional Value and Volatile Compounds
February 27, 2023 (v1)
Subject: Biosystems
Keywords: GC-MS profile, Hass avocado kernels, nutritional value, roasting
Because of the lack of commercial food applications of Hass avocado (Persea americana Mill) kernel, which are a useful agricultural waste and a good source of bioactive compounds, this study investigated the influence of roasting on the chemical composition, antinutritional factors, antioxidant activity, colour, and GC-MS profile in avocado kernels after roasting at 180 °C for 30 min. The nutritional data revealed a significant increase (p < 0.05) in the oil extract, crude fibre, total phenolic compounds, Ca, K, P, Na, Zn, browning index, and redness/greenness after roasting. Conversely, a significant decrease (p < 0.05) was noticed in crude protein, total flavonoids, Fe, antinutrients, lightness, and yellowness/blueness after roasting. The 94 volatile compounds separated by GC-MS included 51 compounds from raw Hass kernels and 65 compounds from roasted kernels. The identified compounds constituted 96.21% and 93.25% in raw and roasted Hass kernels, respectively. The most compound... [more]
27858. LAPSE:2023.11276
In-Situ Hydrothermal Synthesis of Ag3PO4/g-C3N4 Nanocomposites and Their Photocatalytic Decomposition of Sulfapyridine under Visible Light
February 27, 2023 (v1)
Subject: Materials
Keywords: Ag3PO4, g-C3N4, photocatalysis, sulfapyridine, visible light
Highly efficient visible-light-driven heterogeneous photocatalyst Ag3PO4/g-C3N4 with different weight ratios from Ag3PO4 to g-C3N4 were synthesized by a facile in situ hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), photoluminescence spectra (PL), UV−vis diffuse reflectance spectra (UV-Vis), and electrochemical impedance spectra (EIS). Under visible light irradiation, Ag3PO4/g-C3N4 showed very excellent photocatalytic activity for sulfapyridine (SP) which is one of the widely used sulfonamide antibiotics. When the ratio from Ag3PO4 to g-C3N4 was 1:2, the degradation rate of SP at 120 min was found to be 94.1%, which was superior to that of pure Ag3PO4 and pure g-C3N4. Based on the experimental results, the possible enhanced photocatalytic mechanism of Ag3PO4/g-C3N4 was proposed.
27859. LAPSE:2023.11275
Influence of Prefermentative Cold Maceration on the Chemical and Sensory Properties of Red Wines Produced in Warm Climates
February 27, 2023 (v1)
Subject: Biosystems
Keywords: bottle aging, prefermentative cold maceration, red wine, warm climate, wine aromatic profile
Red wines produced in warm climates generally possess a lower content of phenolic compounds and color structure than those produced in colder climates, which hinders bottle evolution. To improve these properties, cold maceration could be a useful procedure. To study the effect of this technique, Tempranillo, Merlot and Syrah grape varieties cultivated in the Jerez area (Southwest Spain) were cold macerated at 4 °C for ten days before alcoholic fermentation. Their composition and characteristics compared to the directly fermented control grapes were analyzed for phenolic content, color, volatile compounds, and sensory properties. It has been verified that phenolic content increased by around 10% during the treatment, which was maintained after the alcohol fermentation, along with an increase in color intensity and aromatic profile. This modification on the composition provided better scores for appearance, aroma intensity, and aroma quality in sensory analysis. The evolution of all stud... [more]
27860. LAPSE:2023.11274
Determination of Electrogenic Potential and Removal of Organic Matter from Industrial Coffee Wastewater Using a Native Community in a Non-Conventional Microbial Fuel Cell
February 27, 2023 (v1)
Subject: Biosystems
Keywords: agro-industrial wastewater, coffee waste, electroactive, MFC, microbial fuel cell, native microbial community
Microbial fuel cells (MFCs) are an alternative to conventional wastewater treatments that allow for the removal of organic matter and cogeneration of electrical energy, taking advantage of the oxidation−reduction metabolism of organic compounds conducted by microorganisms. In this study, the electrogenic potential and the capacity for the reduction of the organic matter of native microbial communities in wastewater from the wet processing of coffee were evaluated using open-cathode MFCs. To determine the electrogenic potential, a factorial experimental design was proposed in which the origin of the residual water and the source of the inoculum were evaluated as factors. The MFCs operated for 21 days in both open-circuit and closed-circuit operation modes. Voltage records, current determinations, and chemical oxygen demand (COD) analyses were used to establish the power reached in the electrochemical system and the degree of the decontamination of the wastewater. During the MFC operatio... [more]
27861. LAPSE:2023.11273
Development of Experimental Techniques for the Phase Equilibrium Study in the Pb-Fe-O-S-Si System Involving Gas, Slag, Matte, Lead Metal and Tridymite Phases
February 27, 2023 (v1)
Subject: Environment
Keywords: lead matte, lead metal, lead slag, phase equilibria experiments
Present society challenges, including metal scarcity, recycling, and environmental restrictions, resulted in the increased complexity and variability of metallurgical feed streams. Metallurgical processes involving complex lead and copper-containing slag and matte phases are now commonly used in response. Optimization of existing and development of new metallurgical processes require fundamental information on slag−matte phase equilibrium. Development of the experimental methodology for the characterization of slag−matte phase equilibrium is presented in the paper. Following a detailed analysis of the potential reaction pathways, experimental techniques have been developed that enable accurate measurement of slag−matte phase equilibrium in the Pb-Fe-O-S-Si system. The application of the techniques has been demonstrated for two important sets of conditions: (i) Condensed phase equilibrium for the slag−matte−metal−tridymite subsystem; and (ii) Gas−slag−matte−tridymite equilibrium at fixe... [more]
27862. LAPSE:2023.11272
Robustness Evaluation Process for Scheduling under Uncertainties
February 27, 2023 (v1)
Subject: Planning & Scheduling
Keywords: decision making, discrete event systems, Industry 4.0, production scheduling, robustness evaluation, uncertainties
Scheduling production is an important decision issue in the manufacturing domain. With the advent of the era of Industry 4.0, the basic generation of schedules becomes no longer sufficient to face the new constraints of flexibility and agility that characterize the new architecture of production systems. In this context, schedules must take into account an increasingly disrupted environment while maintaining a good performance level. This paper contributes to the identified field of smart manufacturing scheduling by proposing a complete process for assessing the robustness of schedule solutions: i.e., its ability to resist to uncertainties. This process focuses on helping the decision maker in choosing the best scheduling strategy to be implemented. It aims at considering the impact of uncertainties on the robustness performance of predictive schedules. Moreover, it is assumed that data upcoming from connected workshops are available, such that uncertainties can be identified and model... [more]
27863. LAPSE:2023.11271
Enzymatic Hydrolysis of Complex Carbohydrates and the Mucus in a Mathematical Model of a Gut Reactor
February 27, 2023 (v1)
Subject: Biosystems
Keywords: chemostat model, compartments, dietary fiber, gut model, hydrolysis, mucins
The human gut microbiota rely on complex carbohydrates for energy and growth, particularly dietary fiber and host-produced mucins. These complex carbohydrates must first be hydrolysed by certain microbial groups to enable cross-feeding by the gut microbial community. We consider a mathematical model of the enzymatic hydrolysis of complex carbohydrates into monomers by a microbial species. The resulting monomers are subsequently digested by the microbial species for growth. We first consider the microbial species in a single compartment continuous stirred-tank reactor where dietary fiber is the only available substrate. A two compartment configuration in which a side compartment connected by diffusion is also studied. The side compartment is taken to be the mucus layer of the human colon, providing refuge from washout and an additional source of complex carbohydrate in the form of mucins. The two models are studied using stability analysis, numerical exploration, and sensitivity analysi... [more]
27864. LAPSE:2023.11270
A Review of Real-Time Fault Diagnosis Methods for Industrial Smart Manufacturing
February 27, 2023 (v1)
Subject: Process Monitoring
Keywords: AI, industrial process monitoring, industrial smart manufacturing, machine condition monitoring, RTFD
In the era of Industry 4.0, highly complex production equipment is becoming increasingly integrated and intelligent, posing new challenges for data-driven process monitoring and fault diagnosis. Technologies such as IIoT, CPS, and AI are seeing increasing use in modern industrial smart manufacturing. Cloud computing and big data storage greatly facilitate the processing and management of industrial information flow, which helps the development of real-time fault diagnosis (RTFD) technology. This paper provides a comprehensive review of the latest RTFD technologies in the field of industrial process monitoring and machine condition monitoring. The RTFD process is introduced in detail, starting with the data acquisition process. The current RTFD methods are divided into methods based on independent feature extraction, methods based on “end-to-end” neural networks, and methods based on qualitative knowledge reasoning from a new perspective. In addition, this paper discusses the challenges... [more]
27865. LAPSE:2023.11269
Dataset of 3β-Corner and 3β-Corner-like Structures
February 27, 2023 (v1)
Subject: Biosystems
Keywords: 3β-corner, 3β-corner-like structure, dataset, structural motif of a protein
The study is devoted to the creation of a dataset of protein structural motifs of the 3β-corner type. The relevance and importance of creating a dataset of 3β-corners is determined by the fact that this structure can be an embryo or a ready-made structural block in the process of protein folding, and can also act as an independent object of research in the field of structural biology. The dataset also contains 3β-corner-like structures that are geometrically similar to 3β-corners. The dataset consists of 45,896 structures. For each motif, its characteristics are presented: the name of the protein in which the 3β-corner is recognized, the method and resolution of the protein structure, the coordinates of localization in the protein, the secondary structure of the amino acid sequence, the gyration radius, the solvent-accessible area, and the composition of the elements of the secondary structure. The dataset will allow a comprehensive study of structures on a large scale and advance the... [more]
27866. LAPSE:2023.11268
Study on the Shadow Effect of the Stress Field around a Deep-Hole Hydraulic-Fracturing Top-Cutting Borehole and Process Optimization
February 27, 2023 (v1)
Subject: Energy Systems
Keywords: fluid–solid coupling, fracture mechanics, prescribed hydraulic fracturing, stress shadow effect
The clean utilization and green development of coal resources have become a research focus in recent years. Underground hydraulic fracturing technology in coal mines has been widely used in roof pressure relief, top coal pre-splitting, gas drainage, roadway pressure relief and goaf disaster prevention. Different in situ stress types cause great differences in the stress field around the boreholes, the critical pressure of the fracture initiation, and the direction of the fracture expansion trend; in addition, the stress shadow effect generated by the superposition of stress fields between boreholes relatively close together has a mutual coupling effect on the evolution of the stress field, the development of the plastic zone, and the crack propagation of the rock mass. Therefore, an effective method to solve the problem is to establish a mechanical model of hydraulic fracturing in boreholes for theoretical calculation, determine the influence mechanism of the crack shadow effect, and d... [more]
27867. LAPSE:2023.11267
Optimization of an Indoor DWC Hydroponic Lettuce Production System to Generate a Low N and P Content Wastewater
February 27, 2023 (v1)
Subject: Optimization
Keywords: daily light integral, deep-water culture, Lactuca sativa L., light-use efficiency, N and P removal, water-use efficiency
Hydroponic production raises economic and environmental issues related to the treatment, recovery or disposal of hydroponic wastewater, which can be rich in eutrophication-related nutrients, nitrogen (N) and phosphorus (P). Little focus has been put on the influence of the growth conditions on the N and P content in hydroponic wastewater, which is of uttermost importance when it is intended to reuse the wastewater for irrigation or other purposes with reduced impact on the environment. This study aimed to optimize an indoor non-recirculating deep-water culture (DWC) hydroponic system for lettuce (Lactuca sativa L. var. crispa) production, in terms of daily light integral (DLI) and volume of nutrient solution (NS) per plant, to maximize both the biomass production and the N and P removal, allowing for the wastewater to meet the criteria established for reusing in irrigation and minimizing the eutrophication impacts. A small-scale DWC hydroponic system with a fluorescent light fixture wa... [more]
27868. LAPSE:2023.11266
Reuse of Carbon Fibers and a Mechanically Recycled CFRP as Rod-like Fillers for New Composites: Optimization and Process Development
February 27, 2023 (v1)
Subject: Optimization
Keywords: carbon fiber reinforced polymers, polymer composites, properties optimization, recycling processes
The rising amount of carbon fiber reinforced polymer (CFRP) composite waste requires new processes for reintroducing waste into the production cycle. In the present research, the objective is the design and study of a reuse process for carbon fibers and CFRP by mechanical recycling consisting of length and width reduction, obtaining rods and reintegrating them as fillers into a polymeric matrix. Preliminary studies are carried out with continuous and discontinuous unidirectional fibers of various lengths. The processing conditions are then optimized, including the length of the reinforcement, the need for a plasma surface treatment and/or for resin post-curing. The resin is thermally characterized by differential scanning calorimetry (DSC), while the composites are mechanically characterized by tensile strength tests, completed by a factorial design. In addition, the composites tested are observed by scanning electron microscopy (SEM) to study the fracture mechanics. Optimal processing... [more]
27869. LAPSE:2023.11265
Optimization and Prediction of Stability of Emulsified Liquid Membrane (ELM): Artificial Neural Network
February 27, 2023 (v1)
Subject: Numerical Methods and Statistics
Keywords: artificial neural network, emulsification time, emulsified liquid membrane (ELM), Span 80, stability, stirring speed
In this work, the emulsified liquid membrane (ELM) extraction process was studied as a technique for separating different pollutants from an aqueous solution. The emulsified liquid membrane used consisted of Sorbitan mono-oleate (Span 80) as a surfactant with n-hexane (C6H14) as a diluent; the internal phase used was nitric acid (HNO3). The major constraint in the implementation of the extraction process by an emulsified liquid membrane (ELM) is the stability of the emulsion. However, this study focused first on controlling the stability of the emulsion by optimizing many operational factors, which have a direct impact on the stability of the membrane. Among the important parameters that cause membrane breakage, the surfactant concentration, the emulsification time, and the stirring speed were demonstrated. The optimization results obtained showed that the rupture rate (Tr) decreased until reaching a minimum value of 0.07% at 2% of weight/weight of Span 80 concentration with an emulsif... [more]
27870. LAPSE:2023.11264
Water Cleaning by a Continuous Fixed-Bed Column for Cr(VI) Eco-Adsorption with Green Adsorbent-Based Biomass: An Experimental Modeling Study
February 27, 2023 (v1)
Subject: Modelling and Simulations
Keywords: chromate, eco-adsorption, fixed bed, process modeling, red peanut skin, Wastewater
In this study, chromate adsorption onto red peanut skin (RPS) was investigated in a fixed-bed column; FTIR, PZC, SEM, DLS, and BET were used to evaluate its adsorption properties. The experiments were conducted to determine the effect of physical parameters, including the inlet initial Cr(VI) concentration (100−500 mg L−1), bed height (10−20 cm), and feed flow rate (13.59−23.45 mL min−1). They were carried out to predict breakthrough curves. The adsorption capacity coefficients were determined using the most widely used Bohart−Adams model. It was tested to fit experimental data, for a better understand the dynamic behavior, and for further optimize column performance. It was found that the Cr(VI) uptake decreases when increasing the flow rate and that high chromate concentration and bed height consequently increase the column’s life span. A high column adsorption capacity can be achieved with a higher Cr(VI) concentration due to the higher driving force. The results indicated that the... [more]
27871. LAPSE:2023.11263
Biogas Production from Residues of Industrial Insect Protein Production from Black Soldier Fly Larvae Hermetia illucens (L.): An Evaluation of Different Insect Frass Samples
February 27, 2023 (v1)
Subject: Biosystems
Keywords: anaerobic digestion, black soldier fly, BMP tests, CSTR digestion, Hermetia illucens, insect frass
Insect biomass shows promise as an alternative animal feedstuff with a low climate effect. Industrial insect rearing generates residual materials, such as feed remains and insect excrements, so-called insect frass, which exhibits a high organic content. Commonly, these residues are utilized as soil amendment. Information on the suitability of these residues for biogas production is rather scarce. The energetic utilization of insect frass as feedstock for anaerobic digestion (AD) would allow for the simultaneous residue material reduction and bioenergy production. Additionally, synergies in heat management could arise using the exhaust heat of the biogas plant in the insect farming process. In laboratory-scale anaerobic digestion trials, the specific methane yield (SMY) of six different insect frass samples from black soldier fly (Hermetia) rearing were tested in batch biochemical methane potential (BMP) tests. Further, semi continuous anaerobic digestion trials on a lab scale using con... [more]
27872. LAPSE:2023.11262
Recent Progress of Non-Pt Catalysts for Oxygen Reduction Reaction in Fuel Cells
February 27, 2023 (v1)
Subject: Energy Systems
Keywords: alloy catalysts, high-entropy alloy catalysts, non-metallic catalysts, ORR, single-atom catalysts (SACs)
In recent years, non-Pt-based ORR catalysts have been developing rapidly and have achieved performance comparable to or even surpassing Pt precious metal catalysts in specific reactions, offering new possibilities for Pt-based catalyst replacement and showing great promise for application. This paper reviews the recent research progress of non-Pt-based fuel cell ORR catalysts. The latest research progress of non-Pt-based ORR SACs (including single metal active site ORR SACs, multi-metal active site ORR SACs, and non-Pt-based noble metal catalyst ORR SACs), non-metallic ORR catalysts, alloy-based ORR catalysts, high-entropy alloy ORR catalysts, and other non-Pt-based fuel cell ORR catalysts are presented in detail. This paper discusses in detail the synthesis methods, characterization means, optimization of performance, and application prospects of these non-Pt-based ORR catalysts. In addition, this review details the excellent performance of these catalysts in terms of compositional an... [more]
27873. LAPSE:2023.11261
Optimized Process for Melt Pyrolysis of Methane to Produce Hydrogen and Carbon Black over Ni Foam/NaCl-KCl Catalyst
February 27, 2023 (v1)
Subject: Process Design
Keywords: carbon black, Hydrogen, melt pyrolysis of methane, Ni foam
Methane pyrolysis transforming CH4 into hydrogen without a CO2 byproduct is a potential hydrogen production process under the net-zero emission target. The melt pyrolysis of methane is a technology that could simultaneously obtain hydrogen and carbon products. However, its catalytic activity and stability are still far from satisfactory. In this work, a new strategy for the melt pyrolysis of methane to hydrogen production was proposed using Ni foam and molten NaCl-KCl. The increase in the amount of Ni foam was found to enhance the methane conversion rate from 12.6% to 18%. The process was optimized by the different amounts of catalysts, the height of the Ni foam layer, and the filling method of Ni foam, indicating that the methane conversion rate of the string method could reach 19.2% at 900 °C with the designed aeration device. Furthermore, we observed that the addition of molten salt significantly alleviated the carbon deposition deactivation of the Ni foam and maintained its macrost... [more]
27874. LAPSE:2023.11260
Treatment Wetlands in Mexico for Control of Wastewater Contaminants: A Review of Experiences during the Last Twenty-Two Years
February 27, 2023 (v1)
Subject: Environment
Keywords: constructed wetlands, ornamental plants, phytoremediation, wastewater treatment
Constructed or treatment wetlands (CWs) are a sustainable option to clean wastewater in the face of water pollution problems. Consequently, this study was aimed at reviewing and analyzing the use of CWs in Mexico. This involved types, sizes, and functionality in the removal of pollutants, as well as the main plant species that are used. Furthermore, 67 studies regarding CWs were found, which were classified according to the treatment area as microcosms, mesocosms, pilot scale, and full-scale at 18, 30, 25, and 27%, respectively. The most used types of CWs are those of subsurface flow (87%) versus free-water surface (13%), of which horizontal flow direction (58%) are the most common. Considering Full-Scale CWs, the pollutant removal reported for COD, BOD5, TN, and TP oscillated between 50−90%, 60−90%, 30−90%, and 30−70%, respectively. Among the vegetation that is more used for Mexican CWs, 78 different species were detected; Typha and Cyperus hydrophytes species and ornamental flowering... [more]
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