Hasil untuk "Chemical industries"

G. Centi, E. A. Quadrelli, S. Perathoner

C. Torborg, M. Beller

F. Goodarzi, S. Zendehboudi

Subhajit Bhattacharjee, Stuart Linley, Erwin Reisner

Xuezhi Bian, Emily A. Carter

Achieving chemical accuracy for molecular simulations remains a central challenge in computational chemistry. Here, we present an embedded correlated wavefunction transfer learning (ECW-TL) framework for accurately simulating molecular dynamics in the condensed phase. ECW-TL incorporates high-level electron exchange and correlation effects in ECW theory while preserving training and computational efficiency of machine learned interatomic potentials. We demonstrate the framework on Ca2+-CO32- ion pairing in aqueous solution, a key process underlying CO2 mineralization in seawater. As proof of principle, we first show that finetuning a DFT-revPBE-D3(BJ) baseline model with embedded-DFT-SCAN data reproduces the DFT-SCAN free-energy surface within 1 kcal/mol across all solvation states. Extending the framework to embedded MP2 and localized natural-orbital CCSD(T) further refines the free-energy profile, revealing the crucial role of exact electron exchange and correlation in determining ion-pair stability and structure. ECW-TL thus provides a general, data-efficient route for transferring CW accuracy to large-scale simulations of complex aqueous and interfacial chemical processes.

Alireza Miraliakbar, Fangyuan Ma, Zheyu Jiang

In this work, we study an integrated fault detection and classification framework called FARM for fast, accurate, and robust online chemical process monitoring. The FARM framework integrates the latest advancements in statistical process control (SPC) for monitoring nonparametric and heterogeneous data streams with novel data analysis approaches based on Riemannian geometry together in a hierarchical framework for online process monitoring. We conduct a systematic evaluation of the FARM monitoring framework using the Tennessee Eastman Process (TEP) dataset. Results show that FARM performs competitively against state-of-the-art process monitoring algorithms by achieving a good balance among fault detection rate (FDR), fault detection speed (FDS), and false alarm rate (FAR). Specifically, FARM achieved an average FDR of 96.97% while also outperforming benchmark methods in successfully detecting hard-to-detect faults that are previously known, including Faults 3, 9 and 15, with FDRs being 97.08%, 96.30% and 95.99%, respectively. In terms of FAR, our FARM framework allows practitioners to customize their choice of FAR, thereby offering great flexibility. Moreover, we report a significant improvement in average fault classification accuracy during online monitoring from 61% to 82% when leveraging Riemannian geometric analysis, and further to 84.5% when incorporating additional features from SPC. This illustrates the synergistic effect of integrating fault detection and classification in a holistic, hierarchical monitoring framework.

Pavlo Kozub, Nataliia Yilmaz, Svitlana Kozub

The study demonstrates the capabilities of a vector-based approach for calculating stoichiometric coefficients in chemical equations, using black powder as an illustrative example. A method is proposed for selecting and constraining intermediate interactions between reactants, as well as for identifying final products. It is shown that even a small number of components can lead to a large number of final and intermediate products. Through concrete calculations, a correlation is established between the number of possible chemical equations and the number of reactants. A methodology is proposed for computing all possible chemical equations within a reaction system for arbitrary component ratios, enabling the derivation of all feasible chemical reactions. Additionally, a method is developed for calculating the chemical composition for a fixed set of reactants, allowing for the evaluation of the set of products resulting from all possible chemical interactions given a specified initial composition.

Angelica Cardoza, Henry A. Colorado

This study shows an alkaline activated cement (AAC), also known as geopolymer, made from red brick waste with partial addition of Ordinary Portland Cement (OPC). This is a sustainable material since incorporates waste from the brick industry to make cements, therefore increasing the materials circularity and this reducing pollution. The material was cured at room temperature. The brick residue was activated with sodium hydroxide and sodium silicate in aqueous solution to form the hybrid cement. Several mixtures were made with different amounts of waste and proportions of alkaline activator. The mechanical properties of the materials were studied to determine their feasibility to be used in the construction sector. Three contents of OPC were used: 10, 20, and 30 wt%, which were added to improve the mechanical behavior and post-curing time. The activated hybrid cement was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), compression, and flexural tests. The main results show that the addition of OPC to the brick derived AAC produces an increased compressive strength of 106 MPa when 30 wt% OPC was added, a very significant result since the control sample found was 33 MPa in compression strength, an improvement for more than 3 times. The data were corroborated by statistical analysis.

Abdessamad Ettouil, Asmaa Oubihi, Hamada Imtara et al.

The extraction of gum from natural raw materials is of increasing importance in various industries, including food, pharmaceuticals, and cosmetics, particularly due to their emulsifying properties and potential applications as stabilizers and thickeners. This study presents an insight on the influence of changing parameters like reagents and operating condition on yield and some properties of the flax (Linum usitatissimum L.) seed gum. The extraction conditions were meticulously examined using a full factorial design, highlighting the significant impact of pretreatment, seed preparation, and solvent selection on the extraction yield. A response surface methodology (RSM) was then applied to optimize the water/benzoic acid ratio of the pretreatment step, the ethyl alcohol/water ratio, and the medium pH of the extraction method, resulting in a maximum yield of 14.47%. Furthermore, detailed analyses of the chemical and emulsifying properties of the gum were conducted showing emulsifying capacities over 94%, offering promising application prospects, particularly in the food industry.

Jing Kong

A physically motivated equation that determines the number of electrons of a molecule is proposed based on chemical common sense. It shows that all molecules are entangled in the number of electrons and results in the fundamental assumption of molecular energy convexity that underpins molecular quantum mechanics. The proposed physical principle includes the molecular size consistency principle as a special case. Application of wavefunction theory to the principle shows that an individual molecule with a noninteger number of electrons is locally physical albeit locally unreal. The energy of a molecule is piecewise linear with respect to its continuous number of electrons. The continuity of the number of electrons allows the definition of an electronic chemical potential of a single molecule. A state function equivalent to the energy of a molecule can be defined using the chemical potential as a variable. The aforementioned physical principle can alternatively be expressed as a simple additivity with the new state function. The latter also shows that the quantum entanglement in the number of electrons can be viewed as all molecules sharing the same chemical potential.

Evelyn Maluleke, Maleho Annastasia Lekganyane, Kgabo L. Maureen Moganedi

Marula wine is produced from ripe fruits of the <i>Sclerocarya birrea</i> subspecies <i>caffra</i> tree through spontaneous fermentation. A few culture-based studies have shown that the fermentation is largely driven by yeasts, although, in the early stages, some lactic acid bacteria (LAB) and acetic acid bacteria may be detected. Some of the microbes may produce undesirable metabolites that lead to the spoilage and short shelf life of the wine. However, there is generally limited information on the microbial composition and its contribution to the chemical characteristics of the resultant marula wine. The aim of this study was to characterise the microbial population of marula wine from different localities in the Limpopo province, South Africa. MALDI-TOF and amplicon sequencing technique were used to identify microbial strains and to determine their diversity and changes in the different stages of fermentation. The phylogenetic relationships of LAB and <i>S. cerevisiae</i> were analysed using multilocus sequence typing. Bacterial species that were common in the different marula wines included <i>Gluconobacter oxydans</i>, <i>Lactiplantibacillus plantarum</i>, <i>Levilactobacillus brevis</i>, <i>Lacitilactobacillus nagelii</i>, <i>Lentilactobacillus kefiri</i> and <i>Lentilactobacillus parabuchneri</i>, and the yeasts were <i>Hanseniaspora guiliermondii</i>, <i>Saccharomyces cerevisiae</i>, <i>Rhodotorula mucilaginosa</i> and <i>Pichia kudriavzevii</i>. The MLST data indicated common microbiota from different marula wines with low intraspecific diversity, suggesting that the LAB and <i>S. cerevisiae</i> strains that are mainly responsible for the spontaneous fermentation of marula wine are similar irrespective of the geographical differences and production preferences.

John P. Hansen, J V Hansen, Jonathan Hansen et al.

Many oil/gas fields in Kazakhstan contain high levels of highly corrosive H2S and CO2, sometimes at very high pressures. The management of corrosion is essential in maintaining plant safety and integrity of the processing facility. This paper describes the development of a non-destructive testing (NDT) method that improves the reliability of air-cooled heat exchangers by reducing down-time related to corrosive and erosive failure of fin-fan tubes. The project goal was to maximize the output of oil and gas plants and refineries while reducing the plant operating cost. The work first identified those NDT requirements for air-cooled heat exchangers damage assessment that would provide the greatest economic benefit for Kazakhstan industry. The main objective was to develop a state-of-an-art NDT method for air-cooled heat exchanger tubes, capable to: a) detect any damage mechanism while testing from tube internal diameter, b) accurately determine the damage in terms of wall loss, c) perform inspection quickly and expediently, d) requires minimum tube cleaning. Consequently, the method specially adapted for Kazakhstan conditions was developed based on a combination of Magnetic Flux Leakage (MFL) technique for flaw detection and with Hall effect measurement of wall thickness and gradual corrosion in tubes. The method has been tested in both laboratory and field conditions and the results were compared with accurate but slow ultrasonic IRIS method. High correlation was obtained, which proved that the developed technology is capable to deliver similar results at the speed almost 10 times faster and less than half the cost.

Micha Livne, Zulfat Miftahutdinov, Elena Tutubalina et al.

Large Language Models (LLMs) have substantially driven scientific progress in various domains, and many papers have demonstrated their ability to tackle complex problems with creative solutions. Our paper introduces a new foundation model, nach0, capable of solving various chemical and biological tasks: biomedical question answering, named entity recognition, molecular generation, molecular synthesis, attributes prediction, and others. nach0 is a multi-domain and multi-task encoder-decoder LLM pre-trained on unlabeled text from scientific literature, patents, and molecule strings to incorporate a range of chemical and linguistic knowledge. We employed instruction tuning, where specific task-related instructions are utilized to fine-tune nach0 for the final set of tasks. To train nach0 effectively, we leverage the NeMo framework, enabling efficient parallel optimization of both base and large model versions. Extensive experiments demonstrate that our model outperforms state-of-the-art baselines on single-domain and cross-domain tasks. Furthermore, it can generate high-quality outputs in molecular and textual formats, showcasing its effectiveness in multi-domain setups.

Kongxing Huang, Guohua Chen, F. Khan et al.

Abstract Domino effects are typically high-impact low-probability (HILP) accidents, which pose a serious threat to chemical process industries. Previous researches on domino effects in chemical industries focus more on static analysis at the spatial scale. From the perspective of the spatial and temporal characteristics of the accident, this study proposed a model to analyze dynamic evolution process of domino effects by using matrix calculation coupled with Monte Carlo simulation, and the dynamic propagation of pool fire accidents is considered as the evolution of domino effects. The algorithm of the model for dynamic domino probabilities considering the synergistic effects of multiple escalation vectors from different units can be used to analyze the complex scenarios of domino effects with high-level and multiple primary accident units. Moreover, the model can be applied in chemical areas with a large number of installations due to the greatly improved calculation efficiency. The proposed model is tested and validated using earlier studied dynamic Bayesian network method, and the application of the model is demonstrated on a complex multi-unit system. The results show that domino effects have strong temporal correlation, and the scenario with multiple primary accident units is much more serious than that with only one primary accident unit, which provide important support for the implementation of emergency response. The study highlights that the proposed model serves as an important tool to evaluate strategies for prevention and control of domino effects.

Khairina Jaman, Nurjannah Amir, Mohammed Ali Musa et al.

Valorization of agro-food waste through anaerobic digestion (AD) is gaining prominence as alternative method of waste minimization and renewable energy production. The aim of this study was to identify the key parameters for digester performance subjected to kinetic study and semicontinuous operation. Biochemical methane potential (BMP) tests were conducted in two different operating conditions: without mixing (WM) and continuous mixing (CM). Three different substrates, including food waste (FW), chicken dung (CD), and codigestion of FW and CD (FWCD) were used. Further kinetic evaluation was performed to identify mixing’s effect on kinetic parameters and correlation of the kinetic parameters with digester performance (volatile solid removal (VS%) and specific methane production (SMP)). The four models applied were: modified Gompertz, logistic, first-order, and Monod. It was found that the CM mode revealed higher values of Rm and k as compared to the WM mode, and the trend was consistently observed in the modified Gompertz model. Nonetheless, the logistic model demonstrated good correlation of kinetic parameters with VS% and SMP. In the continuous systems, the optimum OLR was recorded at 4, 5, and 7 g VS/L/d for FW, CD, and FWCD respectively. Therefore, it was deduced that codigestion significantly improved digester performance. Electrical energy generation at the laboratory scale was 0.002, 0.003, and 0.006 kWh for the FW, CD, and FWCD substrates, respectively. Thus, projected electrical energy generation at the on-farm scale was 372 kWh, 382 kWh, and 518 kWh per day, respectively. Hence, the output could be used as a precursor for large-scale digester-system optimization.

Mario Linz, Jörg Exner, Tobias Nazarenus et al.

Repair instead of discard is going to be crucial in the vision of a green future, therefore we propose the powder aerosol deposition (PAD) as a promising technique to reprocess ceramic coatings at room temperature. Alumina coated copper substrates with an artificial imperfection are manufactured in a first step. In a second step, the repair of this imperfection is carried out using two different PAD apparatuses: first, a conventional PAD apparatus with a moving substrate holder and a converging slit nozzle and second, a miniaturized μPAD apparatus with a fixed substrate holder and a circular de-Laval nozzle. The different film profiles are studied using a laser scanning confocal microscope. Cross-sectional images to investigate the microstructure are taken by a scanning electron microscope. Finally, samples of both PAD apparatuses are exposed to an oxidizing atmosphere at 400 °C proving the gas-tightness as a further quality feature of the repair coating.

Farhad AZİZOV, Zarbali KHALILOV, Vefa ATAYEVA et al.

This investigation aims to study the perspectives for obtaining natural remedies and food addit­ives from raw plant materials that can be used in food, pharmaceutical, and other industries. The selection of hazelnut green leafy cover as an item is based on the fact that it is a natural organic resource that is now being discarded as waste. In the article, the results are presented about the determination of mineral elements and bioactive compounds in the bio-extracts of 70% ethyl alcohol (BE-III) and distillation water (BE-IV) obtained from the green leafy cover of the plant (Corylus avellane L.) where grow in the north-western region of Azerbaijan. According to our study, BE-III has 25 chemical elements, excluding Rb, for a total of 12.797%, while BE-IV contains 26 chemical elements for a total of 21.347%. Amounts of mac­roelements are 10.4%, and microelements are 2.69% in the content of BE-III, while amounts of macroele­ments are 17.82%, and amounts of microelements are 3.53% in the content of BE-IV. Amounts of organic compounds are 87.2% in the content of BE-III, while their amounts are 78.65% in the content of BE-IV. The amount of Zn, which has antioxidant activity, is 0.009%, and the amount of Se is 0.002% in the con­tent of BE-IV. These values vary in the content of BE-III, the amount of Zn is 0.01%, but the amount of Se is 0.001%. 15 bioactive substances were identified in the content of BE-III bio-extract; however, 5 bioact­ive substances were identified in the content of BE-IV bio-extract. According to our research results, the bio-extract obtained from hazelnut green leafy cover is abundant with antioxidants and bioactive sub­stances with antibacterial activity. For this reason, these bio-extracts can be used as both a food supple­ment and a means of treatment.

Saeid Nejati, Sajjad Keshipour, Mozhdeh Seyyedhamzeh

While one of the valuable approaches to obtaining a heterogeneous catalyst is supporting them on a high surface area supports, the strategy mainly suffers from the low number of chelating agents on most of the supports to grip the metal cations catalysts. Therefore, loading multidentate compounds susceptible to binding with metal cations is a potent strategy to improve the catalyst stability on the support. In this report, metformin as a multi-dentate ligand was bonded onto graphene quantum dots as a high aspect ratio compound to afford new support susceptible to chelating Co(II). Deposition of Co(II) on graphene quantum dots modified with metformin gave a new sustainable heterogeneous catalyst that was highly active in the oxidation of alkyl arenes. The reactions were performed in solvent-free conditions at 80 ºC with high conversions up to 96%. The organometallic compound is applicable as a recoverable heterogeneous catalyst with recyclability up to 6 times. The modification of graphene quantum dots with metformin also can gain more attention from medicinal researchers.

J. Łapińska, Iwona Escher, Joanna Górka et al.

The use of artificial intelligence (AI) in companies is advancing rapidly. Consequently, multidisciplinary research on AI in business has developed dramatically during the last decade, moving from the focus on technological objectives towards an interest in human users’ perspective. In this article, we investigate the notion of employees’ trust in AI at the workplace (in the company), following a human-centered approach that considers AI integration in business from the employees’ perspective, taking into account the elements that facilitate human trust in AI. While employees’ trust in AI at the workplace seems critical, so far, few studies have systematically investigated its determinants. Therefore, this study is an attempt to fill the existing research gap. The research objective of the article is to examine links between employees’ trust in AI in the company and three other latent variables (general trust in technology, intra-organizational trust, and individual competence trust). A quantitative study conducted on a sample of 428 employees from companies of the energy and chemical industries in Poland allowed the hypotheses to be verified. The hypotheses were tested using structural equation modeling (SEM). The results indicate the existence of a positive relationship between general trust in technology and employees’ trust in AI in the company as well as between intra-organizational trust and employees’ trust in AI in the company in the surveyed firms.

M. Ostadi, K. Paso, Sandra Rodríguez-Fabià et al.

Integrated water electrolysis is a core principle of new process configurations for decarbonized heavy industries. Water electrolysis generates H2 and O2 and involves an exchange of thermal energy. In this manuscript, we investigate specific traditional heavy industrial processes that have previously been performed in nitrogen-rich air environments. We show that the individual process streams may be holistically integrated to establish new decarbonized industrial processes. In new process configurations, CO2 capture is facilitated by avoiding inert gases in reactant streams. The primary energy required to drive electrolysis may be obtained from emerging renewable power sources (wind, solar, etc.) which have enjoyed substantial industrial development and cost reductions over the last decade. The new industrial designs uniquely harmonize the intermittency of renewable energy, allowing chemical energy storage. We show that fully integrated electrolysis promotes the viability of decarbonized industrial processes. Specifically, new process designs uniquely exploit intermittent renewable energy for CO2 conversion, enabling thermal integration, H2 and O2 utilization, and sub-process harmonization for economic feasibility. The new designs are increasingly viable for decarbonizing ferric iron reduction, municipal waste incineration, biomass gasification, fermentation, pulp production, biogas upgrading, and calcination, and are an essential step forward in reducing anthropogenic CO2 emissions.