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    Wyświetlanie 1-14 z 14
    Tytuł:
    FEDMA - a simple algorithm for theoretical modeling of linear metabolic pathways: from fuzzy data sets to prediction and experiment.
    Autorzy:
    Pawlowski, Piotr
    Zielenkiewicz, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/1041464.pdf
    Data publikacji:
    2005
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    linear metabolic pathway
    chemical kinetics
    algorithm
    theoretical modeling
    Opis:
    A theoretical model of a chain of irreversible Michaelis-Menten reactions proceeding inside a living cell, taking cell growth, division and subcellular compartmentation into account, was proposed. It became a basis for the construction of a "fuzzy" enzymatic data-modeling algorithm (FEDMA) - a procedure allowing the estimation of missing parameter values for the modeled system, in accordance both with the derived theoretical rules and the available experimental data. The obtained tool was tested to model the heme biosynthesis pathway in Saccharomyces cerevisiae, where about 40% of parameters remain unknown. The missing parameters estimated by means of FEDMA fall in the range of expected values.
    Źródło:
    Acta Biochimica Polonica; 2005, 52, 1; 71-86
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Biochemical kinetics in changing volumes.
    Autorzy:
    Pawłowski, Piotr
    Zielenkiewicz, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/1043352.pdf
    Data publikacji:
    2004
    Wydawca:
    Polskie Towarzystwo Biochemiczne
    Tematy:
    glycolytic oscillations
    chemical kinetics
    cyclin oscillations
    varying volume
    Opis:
    The need of taking into account the change of compartment volume when developing chemical kinetics analysis inside the living cell is discussed. Literature models of a single enzymatic Michaelis-Menten process, glycolytic oscillations, and mitotic cyclin oscillations were tested with appropriate theoretical extension in the direction of volume modification allowance. Linear and exponential type of volume increase regimes were compared. Due to the above, in a growing cell damping of the amplitude, phase shift, and time pattern deformation of the metabolic rhythms considered were detected, depending on the volume change character. The perfomed computer simulations allow us to conclude that evolution of the cell volume can be an essential factor of the chemical kinetics in a growing cell. The phenomenon of additional metabolite oscillations caused by the periodic cell growth and division was theoretically predicted and mathematically described. Also, the hypothesis of the periodized state in the growing cell as the generalization of the steady-state was formulated.
    Źródło:
    Acta Biochimica Polonica; 2004, 51, 1; 231-243
    0001-527X
    Pojawia się w:
    Acta Biochimica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Investigation of the cook-off processes of HMX-based mixed explosives
    Autorzy:
    Chen, L.
    Ma, X.
    Lu, F.
    Wu, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/358000.pdf
    Data publikacji:
    2014
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
    Tematy:
    explosives
    chemical kinetics
    thermal decomposition
    cook-off
    numerical simulation
    Opis:
    In order to investigate the characteristics of the thermal reaction for two kinds of mixed explosives, PBXC-10 (HMX/TATB/Binder, 38/57/5) and JO-8 (HMX/Binder, 95/5), multi-point measured temperature cook-off tests were carried out at different heating rates. The thermal transfer and finite chemical reactions that include the β→δ transition of HMX, and the endothermic and exothermic cook-off processes were analyzed. A 3D model of the explosive cook-off test was developed to simulate the thermal and chemical behaviour in a thermal ignition. The decomposition mechanisms for HMX and TATB are described by the multistep, chemical kinetic model. The thermal properties, decomposition pathways, and chemical kinetic reaction rate constants for each component are used to develop the reaction courses at various weight percentages. The thermal decomposition reaction of a multi-component, mixed explosive can be predicted as long as the chemical kinetics model of each single-base explosive and binder are known. The phase transition of HMX has an influence on the temperature of the explosive, especially for an explosive with a high HMX content. For mixed explosives containing HMX and TATB, most of the heat release is produced by the decomposition of HMX before ignition, but TATB can delay the ignition time and decrease the reaction violence in the cook-off process.
    Źródło:
    Central European Journal of Energetic Materials; 2014, 11, 2; 199-218
    1733-7178
    Pojawia się w:
    Central European Journal of Energetic Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A study of the local entropy generation rate in a porous media burner
    Autorzy:
    Mohammadi, I.
    Esfahani, J. A.
    Kim, K. C.
    Powiązania:
    https://bibliotekanauki.pl/articles/38597672.pdf
    Data publikacji:
    2020
    Wydawca:
    Instytut Podstawowych Problemów Techniki PAN
    Tematy:
    porous media burner
    chemical kinetics
    volumetric heat transfer
    axisymmetric combustion
    local entropy generation
    excess air ratio
    Opis:
    In this paper, the work and performance of the premixed methane-air porous axisymmetrical burner have firstly been simulated numerically using the CFD tools. For this purpose the set of governing equations has been enriched by an additional energy equation in porous solid, and the chemical species transport has been extended onto the multi-step mechanism (GRI-2-11). This numerical model has been verified on the base of available benchmark experiments. Next, we have studied the local entropy generation problem taking into account not only classical contributions like viscous and turbulent dissipation but also, the porous combustion of gases. The results showed that the greatest portion of entropy generation in the porous medium burner is related to chemical reactions, followed by heat transfer, mass diffusion (mixing) and friction (viscous dissipation), respectively. According to the results, as the excess air ratio increases, the local entropy generation rate due to heat transfer and friction increases and the local entropy generation rate due to chemical reactions is decreased. Also, by increasing the volumetric heat transfer coefficient, the local entropy generation rate due to heat transfer decreases and the local entropy generation rate due to friction and chemical reactions increases. Also, the local entropy generation rate due to mixing does not show a significant change with the changing excess air ratio and volumetric heat transfer coefficient.
    Źródło:
    Archives of Mechanics; 2020, 72, 3; 257-279
    0373-2029
    Pojawia się w:
    Archives of Mechanics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Numerical study of detonation processes in rotating detonation engine and its propulsive performance
    Badanie numeryczne procesów detonacji w wirującym silniku detonacyjnym i jego wydajności napędowej
    Autorzy:
    Yi, Tae-Hyeong
    Lou, Jing
    Turangan, Cary Kenny
    Wolanski, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/36427720.pdf
    Data publikacji:
    2020
    Wydawca:
    Sieć Badawcza Łukasiewicz - Instytut Lotnictwa
    Tematy:
    detonation wave
    rotating detonation engine
    propulsion
    chemical kinetics
    finite volume method
    adaptive mesh refinement
    fala detonacyjna
    wirujący silnik detonujący
    napęd
    kinetyka chemiczna
    metoda skończonej objętości
    adaptacyjne udoskonalanie siatki
    Opis:
    Numerical studies on detonation wave propagation in rotating detonation engine and its propulsive performance with one- and multi-step chemistries of a hydrogen-based mixture are presented. The computational codes were developed based on the three-dimensional Euler equations coupled with source terms that incorporate high-temperature chemical reactions. The governing equations were discretized using Roe scheme-based finite volume method for spatial terms and second-order Runge-Kutta method for temporal terms. One-dimensional detonation simulations with one- and multi-step chemistries of a hydrogen-air mixture were performed to verify the computational codes and chemical mechanisms. In two-dimensional simulations, detonation waves rotating in a rectangular chamber were investigated to understand its flowfield characteristics, where the detailed flowfield structure observed in the experiments was successfully captured. Three-dimensional simulations of two-waved rotating detonation engine with an annular chamber were performed to evaluate its propulsive performance in the form of thrust and specific impulse. It was shown that rotating detonation engine produced constant thrust after the flowfield in the chamber was stabilized, which is a major difference from pulse detonation engine that generates repetitive and intermittent thrust.
    Przedstawiono badania numeryczne propagacji fali detonacyjnej w wirującym silniku detonacyjnym oraz jego wydajności pędnej z jedno- i wielostopniową mieszanką chemiczną na bazie wodoru. Kody obliczeniowe opracowano w oparciu o trójwymiarowe równania Eulera w połączeniu z pojęciami źródłowymi, które obejmują wysokotemperaturowe reakcje chemiczne. Obowiązujące równania zostały zdyskredytowane przy użyciu metody skończonej objętości opartej na schemacie Roe'a dla terminów przestrzennych oraz metody Runge-Kutta drugiego rzędu dla terminów czasowych. W celu weryfikacji kodów obliczeniowych i mechanizmów chemicznych przeprowadzono jednowymiarowe symulacje detonacji z jedno- i wieloetapowymi chemikaliami mieszaniny wodoru i powietrza. W symulacjach dwuwymiarowych badano fale detonacyjne obracające się w komorze prostokątnej w celu zrozumienia jej charakterystyki pola przepływu, gdzie udało się uchwycić szczegółową strukturę pola przepływu zaobserwowaną w doświadczeniach. Przeprowadzono trójwymiarowe symulacje dwufalowego wirującego silnika detonacyjnego z komorą pierścieniową w celu oceny jego właściwości pędnych w postaci ciągu i impulsu właściwego. Wykazano, że wirujący silnik detonujący wytwarza stały ciąg po ustabilizowaniu się pola przepływu w komorze, co stanowi istotną różnicę w stosunku do silnika detonującego impulsowo, który wytwarza powtarzalny i przerywany ciąg.
    Źródło:
    Transactions on Aerospace Research; 2020, 3 (260); 30-48
    0509-6669
    2545-2835
    Pojawia się w:
    Transactions on Aerospace Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Flameless oxidation at the GT26 gas turbine: numerical study via full chemistry
    Autorzy:
    Ochrymiuk, T.
    Badur, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1955802.pdf
    Data publikacji:
    2001
    Wydawca:
    Politechnika Gdańska
    Tematy:
    combustion
    full kinetics of chemical reaction
    CFD
    computational fluid dynamics CFD
    flameless oxidation
    flameless combustion
    Opis:
    Sequential combustion was first applied to gas turbines more than 40 years ago, and almost half of these early machines are still operating. This form of oxidation leads to the flame-less combustion at a second chamber. In GT26, the second stage combustor has 24 SEV burners which are similar in action to the well known ABB EV burner. In this paper, a 3D numerical simulation of the first EV combustor and the second SEV-combustor are performed for normal operating conditions (exhaust mass flow 542 kg/s, exhaust temperature 610 C). Physical modelling of the flame-less oxidation is based on an original implementation of the Gri-Mech mechanism (325 chemical reactions) into the Fluent 5.4. Precise estimation of NOx emission and other pollutants has been done.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 2; 239-246
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A study on the dissolution kinetics of iron oxide leaching from clays by oxalic acid
    Autorzy:
    Arslan, Volkan
    Powiązania:
    https://bibliotekanauki.pl/articles/1447278.pdf
    Data publikacji:
    2021
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    clay
    physico-chemical characterization
    chemical leaching
    oxalic acid
    dissolution kinetics
    activation energy
    Opis:
    Clay is widely used in a number of industries due to its special properties like fine particle size, brightness and whiteness, chemical inertness, platy structure, etc. In this study, the general characteristics of clays have been investigated by XRF, XRD, FT-IR, TG-DTA and SEM. The presence of iron as an impurity decreases its commercial value due to giving unwanted colors to clay mineral. Therefore, the dissolution capacity of clay ore was investigated by oxalic acid leaching. Under optimized leaching conditions (0.8 M oxalic acid concentration, 85°C reaction temperature, 1.75 ambient pH, 106+75 µm particle size, 15% w/v solids concentration and 150 min. leaching time) with 250 rpm stirring, 83.90% of $Fe_2O_3$ was removed. The amount of iron oxide, the main impurity in the clay, has been reduced from 2.70 to 0.40%. The iron dissolution kinetics was mainly controlled by internal diffusion control of shrinking core model and activation energy, $E_a$, of 26.29 kJ/mol was obtained for the process. The results also showed that the studied clays have adequate characteristics for ceramics industry, earthenware and porcelain production.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2021, 57, 3; 97-111
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Leaching kinetics of atrazine and inorganic chemicals in tilled and orchard soils
    Autorzy:
    Szajdak, L.W.
    Lipiec, J.
    Siczek, A.
    Nosalewicz, A.
    Majewska, U.
    Powiązania:
    https://bibliotekanauki.pl/articles/25267.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Instytut Agrofizyki PAN
    Tematy:
    leaching
    kinetics
    atrazine
    inorganic chemical
    tilled soil
    orchard soil
    Opis:
    The aim of this study was to verify first-order kinetic reaction rate model performance in predicting of leaching of atrazine and inorganic compounds (K+1, Fe+3, Mg+2, Mn+2, NH4 +, NO3 - and PO4 -3) from tilled and orchard silty loam soils. This model provided an excellent fit to the experimental concentration changes of the compounds vs. time data during leaching. Calculated values of the first-order reaction rate constants for the changes of all chemicals were from 3.8 to 19.0 times higher in orchard than in tilled soil. Higher first-order reaction constants for orchard than tilled soil correspond with both higher total porosity and contribution of biological pores in the former. The first order reaction constants for the leaching of chemical compounds enables prediction of the actual compound concentration and the interactions between compound and soil as affected by management system. The study demonstrates the effectiveness of simultaneous chemical and physical analyses as a tool for the understanding of leaching in variously managed soils.
    Źródło:
    International Agrophysics; 2014, 28, 2
    0236-8722
    Pojawia się w:
    International Agrophysics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Separation and physicochemical properties of residual carbon in gasification slag
    Autorzy:
    Fan, Xiaoting
    Fan, Panpan
    Liu, Xiaodong
    Ren, Zhenyang
    Bao, Weiren
    Wang, Jiancheng
    Dong, Lianping
    Fan, Minqiang
    Powiązania:
    https://bibliotekanauki.pl/articles/2175447.pdf
    Data publikacji:
    2022
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    waste treatment
    gasification slag
    physical properties
    chemical properties
    structural features
    reaction kinetics
    Opis:
    Gasification slag is the solid waste produced in the coal gasification process, and its treatment and disposal problems are becoming more and more serious. In this study, the gasification slag produced in a chemical base in northern China and its residual carbon obtained by gravity separation of water medium were taken as the research objects, and their physicochemical properties were analyzed comprehensively. The residual carbon products, ash-rich products and high-ash products were obtained from the gasification slag after gravity separation. Under the optimal structure, the ignition loss of residual carbon products was reduced from 79.80% to 16.84%, and the yield was 11.64%. The high content of amorphous carbon and developed pores in the residual carbon provide the possibility of manufacturing high value-added materials. Raman spectrum showed that the residual carbon had lower aromaticity, higher content of small and medium aromatic ring structures, lower structural stability and easier combustion. Thermogravimetric combustion kinetics showed that the average combustion rate of residual carbon was 0.325(dm/dt)mean/%•min−1, the comprehensive combustion characteristic index was 1.41•10−9%2•min−2•°C−3. It has excellent performance and can be used as a raw material for mixed combustion in a circulating fluidized bed. The analysis of physical and chemical properties of residual carbon is of great significance for follow-up exploration of the resource utilization and high-value utilization of the residual carbon.
    Źródło:
    Physicochemical Problems of Mineral Processing; 2022, 58, 6; art. no. 154928
    1643-1049
    2084-4735
    Pojawia się w:
    Physicochemical Problems of Mineral Processing
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Regularities of Crystallization Heat Release During Solidification of Alloyed Cast Irons
    Autorzy:
    Aftandiliants, Y.
    Gnyloskurenko, S.
    Meniailo, H.
    Khrychikov, V.
    Lomakin, V.
    Powiązania:
    https://bibliotekanauki.pl/articles/27314122.pdf
    Data publikacji:
    2023
    Wydawca:
    Polska Akademia Nauk. Czasopisma i Monografie PAN
    Tematy:
    alloying
    cast irons
    crystallization
    kinetics of crystallization
    chemical composition
    stopowanie
    żeliwo
    krystalizacja
    kinetyka krystalizacji
    skład chemiczny
    właściwości
    Opis:
    The chemical composition of alloys plays an important role at their crystallization and influences the solid phase formation, and thus, microstructure and properties. The present paper studies the release of the heat of crystallization of alloyed wear-resistant cast irons in order to determine the quantitative patterns of the chemical composition influence to the kinetics of crystallization. The differential thermal analysis was applied to get the data of heat release, its rate at cast iron temperature decrease. The normalized dependence of the amount of crystallization heat over time was obtained. The main temperature parameters were analyzed and four stages at irons crystallization were established and characterized with their duration and released heat. The multiple correlation analysis allowed considering a numerous physical and chemical factors and distinguishing their role at crystallization of irons. As a result, the quantitative regularities are determined of influencing the content of alloying elements, impurities and carbides on a heat and time of crystallization at the different stages of solidification, which are of great importance in developing alloyed irons with required quality and properties.
    Źródło:
    Archives of Foundry Engineering; 2023, 23, 1; 110--117
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kinetics of Gases Emission from Surface Layers of Sand Moulds
    Autorzy:
    Zych, J.
    Mocek, J.
    Kaźnica, N.
    Powiązania:
    https://bibliotekanauki.pl/articles/382829.pdf
    Data publikacji:
    2018
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    moulding sand
    surface layer
    gases
    kinetics of gas emission
    chemical binders
    piasek formierski
    warstwa powierzchniowa
    gazy
    emisja gazów
    środki wiążące
    Opis:
    Gas emission from casting moulds, cores and coatings applied for sand and permanent moulds is one of the fundamental reasons of casting defects occurrence. In the previous studies, gas emission was measured in two ways: normalized, in which the evolving gas volume was measured during heating of the moulding sand sample in a sealed flask, or by measuring the amount of gas from sand core (sample) which is produced during the pouring of liquid metal. After the pouring process the sand mould is heated very unequally, the most heated areas are layers adjacent to the liquid metal. The emission of gas is significantly larger from the surface layer than from the remaining ones. New, original method of measuring kinetics of gas emission from very thin layers of sand moulds heated by liquid metal developed by the authors is presented in the hereby paper. Description of this new method and the investigation results of kinetics of gas emission from moulding sand with furan and alkyd resin are shown. Liquid grey cast iron and Al-Si alloy were used as a heat source in the sand moulds. Comparison of the kinetics of gas emission of these two kinds of moulding sands filled with two different alloys was made. The momentary metal temperature in sand mould was assigned to the kinetics of gas emission, what creates a full view of the possibility of formation of casting defects of the gaseous origin. Moulding sand with alkyd resin is characterized by larger gas emission; however gases are emitted slower than in the case of moulding sands with furan resin. This new investigation method has a high repeatability and is the only one which gives a full view of phenomenon’s in the surface layer which determines quality of the casings. The obtained results are presented on several graphs and analyzed in detail. They have a great application value and can be used in the production of iron as well as light metal alloy castings.
    Źródło:
    Archives of Foundry Engineering; 2018, 18, 1; 222-226
    1897-3310
    2299-2944
    Pojawia się w:
    Archives of Foundry Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Physicochemical, thermal and kinetic analysis of sewage sludge
    Fizykochemiczna, termiczna i kinetyczna analiza osadów ściekowych
    Autorzy:
    Nyakuma, B. B.
    Magdziarz, A.
    Werle, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/126178.pdf
    Data publikacji:
    2016
    Wydawca:
    Towarzystwo Chemii i Inżynierii Ekologicznej
    Tematy:
    physical properties of sewage sludge
    chemical properties of sewage sludge
    thermal analysis
    kinetics
    właściwości fizykochemiczne osadów ściekowych
    analiza termiczna
    kinetyka
    Opis:
    Sewage sludge (SS) is the residual matter generated from waste water treatment. Current treatment methods consist of mechanical dewatering and thermochemical treatment, which have become expensive, inefficient and energy consuming. Furthermore, European Union (EU) laws prohibit landfilling, agricultural and storage utilization of sewage slude (SS). Consequently, innovative and sustainable treatment, management and utilization technologies for SS are urgently required. The pyrolysis of sewage sludge can be potentially address the outlined challenges. Therefore, the main aim of this investigation was to examine the physicochemical, thermal and kinetic properties of selected sewage sludge samples (SS1 and SS2). Thermogravimetric analysis was examined to provide comprehensive description of the decomposition behaviour and kinetic characteristics of SS1 and SS2 under pyrolysis conditions at heating rates: 5, 10, 20 and 40°C/min from 30-800°C. The kinetic parameters such activation energy Ea and pre-exponential factor, A were calculated using the Kissinger model. The Ea and A values for SS1 are 205.87 kJ/mol and 9.68 · 1014 whereas SS2 are 320.40 kJ/mol and 7.44 · 1024. The general conclusion based on experimental studies is that the physicochemical and thermal kinetic properties of SS1 and SS2 are comparable with other pyrolysis feedstock and suitable for pyrolysis conversion.
    Osady ściekowe są stałym produktem procesu oczyszczania ścieków. Obecne metody zagospodarowania osadów obejmujące mechaniczne odwadnianie oraz termiczne wykorzystanie stają się drogie, nieefektywne i energochłonne. Co więcej, prawo Unii Europejskiej ogranicza składowanie oraz wykorzystanie rolnicze osadów ściekowych. W efekcie znalezienie innowacyjnych oraz zrównoważonych metod zagospodarowania i utylizacji osadów ściekowych jest niezwykle istotne. Proces pirolizy wydaje się odpowiedni, by sprostać tym wymaganiom. Celem pracy jest określenie fizykochemicznych, termicznych oraz kinetycznych właściwości wybranych próbek osadów ściekowych (SS1 i SS2). Zastosowano analizę termograwimetryczną w celu przeprowadzenia analizy porównawczej opisującej proces przemian termicznych oraz ich kinetyki w warunkach pirolizy dla stałych szybkości grzania wynoszących 5, 10, 20 i 40°C/min w zakresie temperatur od 30-800°C. Parametry kinetyczne: energia aktywacji Ea oraz czynnik przedekspotencjalny A zostały wyznaczone przy użyciu modelu Kissingera. Wartość Ea oraz A dla osadu ściekowego SS1 wynosi odpowiednio 205,87 kJ/mol i 9,68×1014, podczas gdy dla osadu SS2 odpowiednio 320,40 kJ/mol i 7,44×1024. Wyniki analiz zostały porównane z innymi materiałami poddawanymi pirolizie.
    Źródło:
    Proceedings of ECOpole; 2016, 10, 2; 473-480
    1898-617X
    2084-4557
    Pojawia się w:
    Proceedings of ECOpole
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Kinetics of the continuous reaction crystallization of barium sulphate in BaCl2 - (NH4)2SO4 - NaCl - H2O system - neural network model
    Autorzy:
    Piotrowski, K.
    Koralewska, J.
    Wierzbowska, B.
    Matynia, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/778848.pdf
    Data publikacji:
    2009
    Wydawca:
    Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
    Tematy:
    siarczan baru
    jony sodu
    sole pohartownicze
    hartowanie stali
    chlorek baru
    kinetyka krystalizacji
    barium sulphate
    sodium ions
    used quenching salts
    steel hardening
    barium chloride
    reaction crystallization kinetics
    population density distribution
    chemical neutralization
    solid waste utilization
    neural network model
    Opis:
    One of the main toxic components of post quenching salts formed in large quantities during steel hardening processes is BaCl2. This dangerous ingredient can be chemically neutralized after dissolution in water by means of reaction crystallization with solid ammonium sulphate (NH4)2SO4. The resulting size distribution of the ecologically harmless crystalline product - BaSO4 - is an important criteria deciding about its further applicability. Presence of a second component of binary quenching salt mixture (BaCl2-NaCl) in water solution, NaCl, influences the reaction-crystallization process kinetics affecting the resulting product properties. The experimental 39 input-output data vectors containing the information about the continuous reaction crystallization in BaCl2 - (NH4)2SO4 - NaCl - H2O system ([BaCl2]RM = 10-24 mass %, [NaCl]RM = 0-12 mass %, T = 305-348 K and τ = 900-9000 s) created the database for the neural network training and validation. The applicability of diversified network configurations, neuron types and training strategies were verified. An optimal network structure was used for the process modeling.
    Źródło:
    Polish Journal of Chemical Technology; 2009, 11, 4; 13-19
    1509-8117
    1899-4741
    Pojawia się w:
    Polish Journal of Chemical Technology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Adsorption kinetics of fluoride on bone char and its regeneration
    Autorzy:
    Hu, J.
    Wu, D.
    Rao, R.
    Liu, R.
    Lai, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/206892.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    chlorine compounds
    fluorine compounds
    ions
    sodium compounds
    sulfur compounds
    adsorption kinetics
    chemical reaction equilibrium
    correlation coefficient
    Freundlich equation
    optimal conditions
    layered double hydroxides
    aqueous-solution
    drinking water
    equilibrium
    adsorbent
    związki chloru
    związki fluoru
    jod
    związki sodu
    związki siarki
    kinetyka adsorpcji
    równowaga reakcji chemicznej
    współczynnik korelacji
    równanie Freundlicha
    woda pitna
    równanie Langmuira
    Opis:
    The adsorbent of bone char (BC), produced from the pyrolysis of crushed animal bones, was dominated by the mesopores of the Brunauer Emmett Teller (BET) surface area. The optimal condition for defluoridation with BC was a pH level near 5.0. Chloride and nitrate ions could increase fluoride adsorption capacity in contrast with the effect of sulfate and carbonate ions. The interchangeability between fluoride and hydroxyl groups on BC sorbent was proved by the Fourier transform infrared spectroscopy. Langmuir equation had a better correlation coefficient than the Freundlich equation at various temperatures. Thermodynamic parameters such as Delta G degrees, Delta H degrees, Delta S degrees, Ea and S*, have been calculated to describe the nature of fluoride adsorption onto BC. Negative Delta G degrees and Delta H degrees values at various temperatures indicate a spontaneous process, and its exothermic effect, respectively. However, a positive Delta S degrees value represents an increasing process for entropy. The E-a and S* values ranging from 5 to 40 kj.mol-1 and 0 to 1, respectively, demonstrated that the adsorption is dominated by physical process, although the adsorption kinetic process was involved external diffusion, intraparticle diffusion and chemical reaction equilibrium stage. A high concentration of NaOH solution increases efficiency of removing adsorbed F- ions from the BC surface.
    Źródło:
    Environment Protection Engineering; 2017, 43, 3; 93-112
    0324-8828
    Pojawia się w:
    Environment Protection Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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