Conventional Thermal Processing Research Articles

Design of Mixed-Matrix MOF Membranes with Asymmetric Filler Density and Intrinsic MOF/Polymer Compatibility for Enhanced Molecular Sieving.

The separation of high-value-added chemicals from organic solvents is important for many industries. Membrane-based nanofiltration offers a more energy-efficient separation than the conventional thermal processes. Conceivably, mixed-matrix membranes (MMMs), encompassing metal-organic frameworks (MOFs) as fillers, are poised to promote selective separation via molecular sieving, synergistically combining polymers flexibility and fine-tuned porosity of MOFs. Nevertheless, conventional direct mixing of MOFs with polymer solutions results in underutilization of the MOF fillers owing to their uniform cross-sectional distribution. Therefore, in this work, a multizoning technique is proposed to produce MMMs with an asymmetric-filler density, in which the MOF fillers are distributed only on the surface of the membrane, and a seamless interface at the nanoscale. The design strategy demonstrates five times higher MOF surface coverage, which results in a solvent permeance five times higher than that of conventional MMMs while maintaining high selectivity. Practically, MOFs are paired with polymers of similar chemical nature to enhance their adhesion without the need for surface modification. The approach offers permanently accessible MOF porosity, which translates to effective molecular sieving, as exemplified by the polybenzimidazole and Zr-BI-fcu-MOF system. The findings pave the way for the development of composite materials with a seamless interface.

Methanol-based thermochemical energy storage (TCES) for district heating networks

With increasing volatility in natural gas markets and the need for residential heat, research for alternative thermal systems based on green hydrogen-based fuels is necessary. Massive implementation of hydrogen in the current fleet presents a challenge for the decarbonisation of conventional thermal processes. This paper presents the integration of green methanol from a seasonal thermochemical energy storage system (TCES) coupled with district heating networks (DHN). It allows for a solar-based storage and low-temperature heat generation from the exothermic discharge reaction. The system uses concentrated solar thermal energy to decompose methanol into syngas at moderate temperatures (<315 °C), reducing GHG emissions from combustion to meet residential heat. Its potential is assessed through an analysis of 458 rural municipalities in Spain, achieving a substitution of 3.1 % of the natural gas demand. The system allows the production of green fuels from syngas using an open-loop approach, offering new market pathways in primary sector. In a closed-loop configuration, roundtrip efficiencies exceeding 60 % and chemical conversion efficiencies exceeding 70 % are reached, resulting in a global efficiency of 12 % for the DHN and methanol-TCES. The results show a levelized cost of stored energy highly competitive with other storage systems (<200€/MWh), given its simplicity.

Rapid thermal process for fabricating α-alumina tight ultrafiltration membrane with narrow pore size distribution

The development of tight ceramic ultrafiltration membranes for water purification facilitates is challenging because of high fabrication costs and low permeate flux. In this study, a low-energy rapid thermal process (RTP) was comprehensively investigated for fabricating of high-precision, permeable α-alumina tight ultrafiltration membranes. Compared to the conventional thermal process (CTP), RTP offers an ultra-fast heating rate and shorter holding time, effectively mitigating grain growth and pore aggregation. Moreover, the decomposition of organic matter is delayed during RTP, providing a lower interfacial energy that enables direct formation of α-alumina at a low temperature of 750 °C. During a secondary subsequent RTP, the residual phase is fully converted to α-alumina by the in-situ seeding effect. By utilizing RTP, we successfully prepared α-alumina ultrafiltration membranes within 30 min by calcination, with an average pore size of approximately 6 nm, a narrow pore distribution coefficient of 1.12, and high permeance of 219 L−1·m−2·h−1·bar−1.

Electrocatalysis Boosts the Methanol Thermocatalytic Dehydrogenation for High-Purity H2 and CO Production.

Hydrogen production from methanol represents an energy-sustainable way to produce ethanol, but it normally results in heavy CO2 emissions. The selective conversion of methanol into H2 and valuable chemical feedstocks offers a promising strategy; however, it is limited by the harsh operating conditions and low conversion efficiency. Herein, we realize efficient high-purity H2 and CO production from methanol by coupling the thermocatalytic methanol dehydrogenation with electrocatalytic hydrogen oxidation on a bifunctional Ru/C catalyst. Electrocatalysis enables the acceleration of C-H cleavage and reduces the partial pressure of hydrogen at the anode, which drives the chemical equilibrium and significantly enhances methanol dehydrogenation. Furthermore, a bilayer Ru/C + Pd/C electrode is designed to mitigate CO poisoning and facilitate hydrogen oxidation. As a result, a high yield of H2 (558.54 mmol h-1 g-1) with high purity (99.9%) was achieved by integrating an applied cell voltage of 0.4 V at 200 °C, superior to the conventional thermal and electrocatalytic processes, and CO is the main product at the anode. This work presents a new avenue for efficient H2 production together with valuable chemical synthesis from methanol.

Rapid Thermal Processing and Improved Photocatalysis of Bi2O3-BaTiO3 Heterojunction

Bi2O3-BaTiO3 heterojunction with high photocatalysis efficiency was directly synthesized by rapid thermal processing (RTP). Bi2O3 and BaTiO3 were mixed in ratio and treated by RTP and conventional thermal processing (CTP), respectively. RTP samples have obvious Bi2O3 diffraction peaks, while CTP samples show pure BaTiO3 tetragonal perovskite. More small particles and layered existed in RTP samples. Photodegradation of MB solutions shows that RTP can promote photocatalytic efficiency. Its main lies in the following points: RTP can remove grain boundary defects by strengthening the bond grains; RTP can limit the solution region of the two substances to a certain range to get the best built-in electric field width; and RTP can strengthen the tetragonal BaTiO3 phase to hasten ion movement. Therefore, RTP can achieve much higher photocatalytic efficiency by improving the build heterojunction. This work provides a direct and efficient route to get improvement and high performance of heterojunction.

Predicting dielectric properties of fruit juices at 915 and 2450 MHz using machine learning and physicochemical measurements

Microwave-assisted thermal processing can provide superior quality for fruit-based products when compared to conventional thermal processing. Understanding the temperature-dependent dielectric properties of liquid foods is needed for the analysis and optimization of the microwave applicator chamber since they govern the heating rate and temperature distribution. While literature offers correlations for specific products, there is a scarcity of methods capable of accommodating variability in composition or predicting behavior for broader product groups. In this study, we measured the dielectric properties (dielectric constant and loss factor) of eight fruit juices (passion fruit, melon, pineapple, cashew, orange, lemon, acerola, and guava) using an open-ended coaxial-line technique for temperatures ranging from 5 to 90 °C at commercial frequencies of 915 and 2450 MHz, alongside electrical conductivity. These properties were successfully correlated with the temperature for each individual juice; then, machine learning techniques (random forest, gradient boosting machine, and multilayer perceptron) were used to predict the properties of this diverse group of eight juices based on various physicochemical measurements. These techniques revealed temperature and electrical conductivity as the most critical predictors, while total solids, pH, acidity, ashes, and select color parameters also emerged as significant variables. These findings demonstrate that the integration of physicochemical analyses with machine learning tools offers an objective approach to correlate and predict dielectric properties for a group of food products, facilitating adjustments in product composition without additional measurements, thus enhancing the efficiency and accuracy of microwave-assisted thermal processing simulations and optimizations.

Sustainable biomimetic solar distillation with edge crystallization for passive salt collection and zero brine discharge

The urgency of addressing water scarcity and exponential population rise has necessitated the use of sustainable desalination for clean water production, while conventional thermal desalination processes consume fossil fuel with brine rejection. As a promising solution to sustainable solar thermal distillation, we report a scalable mangrove-mimicked device for direct solar vapor generation and passive salt collection without brine discharge. Capillarity-driven salty water supply and continuous vapor generation are ensured by anti-corrosion porous wicking stem and multi-layer leaves, which are made of low-cost superhydrophilic nanostructured titanium meshes. Precipitated salt at the leaf edge forms porous patch during daytime evaporation and get peeled by gravity during night when saline water rewets the leaves, and these salt patches can enhance vaporization by 1.6 times as indicated by our findings. The proposed solar vapor generator achieves a stable photothermal efficiency around 94% under one sun when treating synthetic seawater with a salinity of 3.5 wt.%. Under outdoor conditions, it can produce 2.2 L m−2 of freshwater per day from real seawater, which is sufficient for individual drinking needs. This kind of biomimetic solar distillation devices have demonstrated great capability in clean water production and passive salt collection to tackle global water and environmental challenges.

In‐Liquid Plasma Catalysis: Tools for Sustainable H2‐free Heavy Oils Upgrading

AbstractNon‐thermal plasma (NTP) catalysis, mirroring the trend towards non‐conventional electron‐mediated molecular activation, unfolds novel routes for chemical reactions. Operating at ambient pressure, lower temperatures, and energized by electricity that can powered by renewable sources, NTP offers a cost‐effective and efficient means of sustainable fuel production. This approach has the potential to revolutionize the oil and gas industry, meeting current energy demands while circumventing the challenges posed by conventional thermal catalysis processes, thereby enhancing environmental sustainability and energy security. Through an exploration of the synergistic effects between plasma, catalysis, and hydrocarbon molecules, this concept paper emphasizes the significant advancements made in in‐liquid plasma catalysis strategies for fuel production from heavy oil upgrading. We also provide insights into the heterogeneous catalyst design and the role of plasma gas as an additional catalyst for achieving efficient and sustainable energy solutions. The prospects of in‐liquid plasma catalysis, emphasizing its transformative role in shaping the energy future, are also discussed.

Cu2ZnSnS4 formation by laser annealing in controlled atmosphere

Laser annealing is an attractive process to form high-quality semiconductor films because of localized annealing area and short annealing time. In a previous study, a Cu2ZnSnS4 (CZTS) polycrystalline semiconductor film was realized using laser annealing in air as a light absorption layer for solar cells, although the crystallization was not sufficient in comparison with CZTS formed by the conventional thermal sulfurization process. In this study, we demonstrate a newly developed gas-atmosphere-controlled laser annealing system. A Cu–Zn–Sn–S-based precursor was formed, followed by laser annealing of the system. Laser annealing in air, Ar, and 5% H2S/Ar gas was performed to investigate the influence of the gas species on the crystallization of the precursor. A 5% H2S/Ar atmosphere promoted the crystallization of CZTS with the suppression of S desorption and Cu sulfide formation, while air and Ar atmospheres allowed the formation of Cu sulfide.

Fate of chlordecone during home cooking processes – Transfer into the liquid and aerial phases by conventional thermal processes

This study focuses on the fate of chlordecone (CLD) during cooking processes. Neat CLD was subjected to thermogravimetric analysis, which revealed that the vast majority of the compound (79 %) was vaporised at temperatures between 55 and 245 °C. In order to monitor the behaviour of CLD during cooking processes, a QuEChERS extraction protocol was optimised for vegetable cooking oil and a heating kinetics experiment was conducted at 195 °C on CLD-spiked cooking oil. The results showed a strong decrease in CLD over time and, for the first time to our knowledge, transformation of CLD into chlordecol. Finally, a comparison was conducted between the cooking of uncured pork with and without vegetable oil. The use of vegetable oil led to a significant decrease in CLD content, but revealed that a fraction of the CLD transferred into the cooking oil. This study provides data that shed light on the fate of CLD during cooking.

Facile interfacial defect healing in solution-processed In-Ga-Zn-O thin film transistor through rapid intense pulsed light annealing

We introduce intense pulsed light (IPL) annealing as a versatile and cost-effective interface treatment approach for solution-processed In-Ga-Zn-O thin film transistor, focusing on its potential to improve its operational stability. We fabricate solution-processed IGZO-based thin film transistors (IGZO-TFTs) and systematically investigate the dependence of IPL shot numbers on key parameters that dictate the electrical characteristics of the devices. Under identical positive bias stress (PBS) conditions, we compare the operational stability of IGZO-TFTs treated with IPL annealing during ∼5 min to those subjected to conventional high-temperature thermal processes during 2 h, and reveal that IPL-annealed IGZO-TFTs exhibit superior stability as well as significantly suppressed threshold voltage shifts by ∼22 % (from 3.31 to 2.58 V). To gain deeper insights, we employ photo-excited charge collection spectroscopy analysis, which provides quantitative evidence of the rapid recovery of oxygen vacancies and hydrogen-related interfacial defect states (located at 2.1 ∼ 2.5 eV and near 2.79 eV below conduction band minimum) affecting operational device stability. Our findings underscore the technical advantages of IPL annealing over time-consuming thermal processes, positioning it as a promising method for optimizing IGZO-TFT performance.

Structure and electrochemical behavior of coatings from complex concentrated alloys deposited by Metco Triplex Pro-210 gun

Complex concentrated alloys (CCAs) have gained a significant attention in the engineering and research community due to their unique phase structure and exceptional properties. CCAs are usually comprised of five or more principal alloying elements mixed in near-equimolar or equimolar ratio, which can derive their qualities from multiple principal elements owing to cocktail effect. In this study, atmospheric plasma spraying system equipped with a Metco Triplex Pro-210 gun was used to deposit CCAs designed coating compositions onto SS-316L steel substrate. The microstructure, mechanical and electrochemical behavior of the developed (CoCrFeNiMnx) CCAs were analyzed and compared to commercially used WC-17Co (Diamalloy 2005NS) and NiCr-75Cr2C3 (Metco 81NS) coatings deposited by APS Metco Triplex Pro-210 cascading arc plasma spray gun. The experimental results confirm that using Metco Triplex Pro-210 it is possible to manufacture a CCA coating layers with lower porosity, excellent phase stability in compare to conventional thermal spray processes. Coating characterization also reveals that the CCA coating’ grains experienced a significant amount of grain refinement as compared to those in as-received CCA feedstock powder materials due to the occurrence of shot peening effect and dynamic recrystallization caused by highly deformed splat boundaries during spraying process. The electrochemical results indicates that the CCA coatings have a lower corrosion rate in compare to its plasma sprayed counterparts.

Degassing Dissolved Oxygen through Bubbling: The Contribution and Control of Vapor Bubbles

An innovative yet sustainable approach for industrial deaeration is proposed, with demonstrated results and analyses, to contribute to finding solutions to improve energy efficiency in this field. Vacuum bubbling deaeration, sharing the same working principles of solubility control and the mass diffusion through vapor (or steam) with conventional thermal deaeration processes, works, however, at lower vacuum pressures. It neither resorts to heating nor requires any third-party materials such as membranes or gases, achieving orders of magnitude of reduction in the expected energy consumption in a simple and concrete way. In this study, the mechanisms of vapor bubble generation and retention were discussed by employing a vacuum bubbling model based on the experimental apparatus at Kongju National University, which uses a venturi-nozzle bubbler. The four parameters influencing vapor bubble generation and retention were identified as vessel pressure p1, nozzle depth Δh, nozzle performance p4−p3, and water temperature Tw. A series of deaeration experiments using the present approach for a tap water sample of 360~400 L were conducted under four different conditions to investigate the effects of the water temperature, vessel pressure, and bubbler nozzle depth. Final dissolved oxygen (DO) concentrations close to zero could be achieved with a vessel pressure of p1=1 kPa, with different bubbling times to reach a zero mg/L reading of DO concentration (case 2 and 3), which demonstrates the vital roles of the vapor bubble generation condition of (psat−p3) and retention condition of (p4−psat) in achieving the lowest DO concentration. Analysis of the test results, based on the discrete-bubble model with the measured DO concentrations and degassing rates, showed promising results in reproducing the experimental data. Though the potential of vacuum bubbling deaeration is demonstrated, for the first time, to its full extent, further research efforts are encouraged in many areas, including more case-specific validation test cases with optimum operating conditions along with the study of more detailed modeling for performance prediction, including energy analysis.

Electrochemical splitting of methane in melts: Producing and tuning high-value carbon materials with controllable morphology

Catalytic decomposition of methane offers a viable solution for producing pure hydrogen and nanocarbon without emitting carbon dioxide. However, conventional thermal catalytic processes and catalysts have limitations in terms of poor carbon quality and catalyst deactivation due to carbon deposition. The newly developed electrochemical splitting of methane (ESM) in molten salt has emerged as a promising alternative that allows for the separate production of hydrogen at the anode and carbon deposition at the cathode. In this study, hydrogen produced via ESM while generating nanocarbon with diverse structures through manipulations of the cathode material and kinetics. Carbon nanotubes grown on Ni cathode, possessing high specific surface area and abundant functional groups, displayed excellent adsorptive capacity for dye adsorption. The open hollow nanocarbon grown on the Ag cathode displayed good capacitance performance. ESM technology has immense potential to enhance the utilization value of carbon by-products and the commercial production of green hydrogen.

Rheological and Physical Properties Affected by the Thermal Processing of Fruit: A Bibliometric Analysis

This work describes a bibliometric analysis of recent articles addressing the applications of thermal processing in foods, as well as its effect on their physicochemical and rheological properties. The analysis involved utilizing the software tools VOSviewer and RStudio to map the knowledge domain. Initially, 665 articles from peer-reviewed journals were retrieved, but only 92 (13.8%) of them discussed thermal processing related to fruit applications and were published in indexed journals. However, this number was further narrowed down to 35 (5.3%) articles specifically focused on the target subject. A rigorous appraisal of these 35 articles allowed it to be classified according to its aim, kind of fruit used, thermal processing treatment, and its rheological, physicochemical, and other properties. The leading countries in the general area of food thermal processing research according to documents and citations were China, USA, Brazil, India and Spain. It is important to highlight that conventional thermal processing continues to be investigated for applications in fruits; on the other hand, it is expected that the use of unconventional or emerging technologies will bring significant advances to the food industry in the future.

Visible Light Induced Difunctional Hetero‐Annulation of Unsaturated C−C Bonds

AbstractHeterocyclic scaffolds are beneficial structural architects in a wide range of pharmaceuticals, agrochemicals, biological and also functional materials. In this regard, several investigations have been performed to synthesize them. Among these, visible light‐induced difunctionalization cyclization strategy provides attractive solutions by adopting greener routes, breaking the monopoly of conventional thermal processes. A review on these methodologies is also desirable as unsaturated aliphatics, especially alkenes are one of the cheapest feedstocks available. They offer diverse options and modifications to generate different products, including heterocycles, which are highly sought after due to their applications in various sectors. To account for the advancements in this strategy, we summarized the visible light induced difunctionalization strategies that directly lead to the synthesis of heterocyclic scaffolds from unsaturated C−C bonds. We have categorized the relevant reaction schemes into four mechanistically distinct sections namely (i) Two component oxidative annulations (ii) Radical mediated annulations (iii) Polar radical crossover annulations and (iv) Three component oxidative annulations.

Radio Frequency Treatment of Food: A Review on Pasteurization and Disinfestation.

Radio frequency (RF) is a novel technology with several food processing and preservation applications. It is based on the volumetric heating generated from the product's dielectric properties. The dielectric properties of each material are unique and a function of several factors (i.e., temperature, moisture content). This review presents a list of dielectric properties of several foods and describes the use of RF as an innovative technology for the food industry. This paper includes several examples of pasteurization, fungi inactivation, and disinfestation in selected food products. The aim of this review is to present the potential applications of RF in pasteurization and disinfestation and research needs that should be addressed. RF has been successfully applied in the inactivation of pathogens such as Salmonella spp., Listeria monocytogenes, and Escherichia coli in low- and high-moisture food. The disinfestation of crops is possible using RF because of selective heating. This process inactivates the insects first because of the different dielectric properties between the pests and the food. The products' final quality can be considerably better than conventional thermal processes. The processing time is reduced compared to traditional heating, and thermal damage to the food is minimized. The main drawback of the technology is the lack of uniform heating, mainly when the product is surrounded by a packaging material with different dielectric properties from the food.

Synthesis of solid NMC622 particles by spray drying, post-annealing and lithiation

Layered lithium-nickel-manganese-cobalt oxide (NMC) cathode materials are widely used in Li-ion batteries that require high energy densities, such as those used in plug-in hybrid electric vehicles (PHEVs) and electric vehicles (EVs). Here we studied the synthesis of NMC622 particles by spray pyrolysis, which is a simple one-step process for production of spherical particles. However, synthesising NMC powder using spray pyrolysis has a tendency to produce hollow NMC particles. To gain insight into the mechanism behind the formation of the hollow particles, one dimensional numerical simulation of the physical and chemical phenomena taking place during spray drying were carried out. The effects of several process parameters, including drying air temperature, drying air mass flow rate, and liquid feed mass flow rate, on the evaporation and particle formation process were studied. The increased evaporation rate at higher temperatures was found to result in crust formation on the droplet surface during the particle formation, and thus, in lower solid volume fractions in the dried particles. However, by optimizing the process parameters production of solid NMC622 sulphate particles by spray drying was achieved. The produced NMC622 sulphate particles were then oxidised and lithiated in air at 850 °C via the conventional thermal treatment process. Four lithium precursors, LiOH, Li2CO3, Li2SO4 and LiNO3, were tested for the lithiation of the oxidized NMC particles. The degree of lithiation and the crystalline phase of the powders were determined using ICP-OES and XRD, respectively.

Thermal crosslinking and cyclodehydration assisted fabrication of chemically robust thin-film composite (TFC) membranes for ultrafast polar solvents filtration

Organic solvent nanofiltration (OSN) offers an energy-efficient alternative to conventional thermal distillation processes for organic solvent separations. However, the fabrication of polymeric OSN membranes with adequate chemical stability in strong polar aprotic solvents remains a remarkable challenge. In this work, chemically robust polyamide thin-film composite (TFC) OSN membranes were fabricated by utilizing an innovative chemical modification of polyimide (PI) nanofiber substrate via one-step crosslinking and thermal cyclodehydration of terephthalic hydrazide (TPDH). The crosslinking and cyclodehydration reaction mechanisms were thoroughly elucidated and the effects of TPDH loading and thermal treatment conditions on solvent resistance and pore structure of the resulting TPDH/PI nanofiber substrates as well as the formation of the polyamide selective layer were systematically studied. The resulting TFC membranes show excellent stability in polar aprotic solvents (i.e., DMF, DMAC, and NMP), and a high DMF permeance of 9.4 L m−2 h−1 bar−1 was achieved with a 99.8% rejection to Rose Bengal at 2.0 bar. The outstanding long-term performance stability revealed the robust structure of the developed TFC OSN membranes. This work demonstrates a facile strategy to address the chemical stability limitations of TFC OSN membranes through a multifaceted yet generalizable approach of chemical crosslinking and thermal cyclodehydration. We believe this strategy can be broadly applied to different substrates, enabling TFC membranes to address a wide variety of unmet OSN needs.

Non-Thermal Supercritical Carbon Dioxide Processing Retains the Quality Parameters and Improves the Kinetic Stability of an Araticum Beverage Enriched with Inulin-Type Dietary Fibers.

Fruit-based beverages have been considered excellent food vehicles for delivering prebiotics. However, the conventional thermal processes currently used to microbiologically and enzymatically stabilize these products may cause significant losses in their sensory, physicochemical, nutritional, and bioactive characteristics. Thus, in this study, we evaluate the effect of different levels of pressure (8, 15, and 21 MPa) and temperature (35 and 55 °C) on the characteristics of an inulin-enriched araticum beverage processed with non-thermal supercritical carbon dioxide (SC-CO2) technology. The temperature showed a significant effect on total soluble solids, pH, particle size distribution, and kinetic stability. In contrast, pressure affected only the particle size distribution. The interaction between pressure and temperature influenced the total soluble solids, pH, and particle size distribution. Color parameters, ζ-potential, and glucose and fructose contents were not modified after all SC-CO2 treatments. Moreover, the SC-CO2 treatments preserved the inulin molecular structure, thus maintaining its prebiotic functionality. Overall, the SC-CO2 treatment did not alter the sensory, nutritional, and functional quality of the beverage, while improving its physical stability during storage. Therefore, non-thermal SC-CO2 treatment can be an alternative to current conventional processes for stabilizing inulin-enriched fruit-based beverages.