Kinetic studies of 5-(hydroxymethyl)-furfural formation and change of the absorption at 420 nm in fruit juices for the improvement of pasteurization plants

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Linda Katsch ◽  
Frank-Jürgen Methner ◽  
Jan Schneider
Keyword(s):  
Activation Energy ◽  
Color Change ◽  
Reaction Order ◽  
Kinetic Studies ◽  
Chemical Conversion ◽  
Lethal Effect ◽  
Microbial Inactivation ◽  
Exponential Factor ◽  
Hydroxymethyl Furfural ◽  
Kinetics Of

Abstract Preservation of juices is essential to obtain microbial safe products. There are various established methods as pasteurization. Heretofore, only the kinetic figures of microbial inactivation were considered but not those of reaction impairing the chemical quality. For a gentler processing, knowledge of the kinetics of relevant chemical conversion reactions is necessary. 5-(Hydroxymethyl)-furfural (HMF) formation and the color change of juices are important attributes. The non-isothermal Rhim method was used to determine the activation energy and pre-exponential factor for HMF formation in different juices and an isothermal method for the reaction order. Values for the activation energy from 133 to 303 kJ/mol were obtained with a zeroth reaction order. A correlation between HMF and the color change could be found. Based on the kinetic figures, lines with equal effects for the chemical changes and for the lethal effect on microorganisms were calculated. Time-temperature settings for the gentlest treatment could be found.

scholarly journals Kinetics of the Carbon Monoxide Oxidation Reaction Under Microwave Heating

1996 ◽  
Vol 430 ◽  
Author(s):  
W. Lee Perry ◽  
Joel D. Katz ◽  
Daniel Rees ◽  
Mark T. Paffett ◽  
Abhaya Datye
Keyword(s):  
Activation Energy ◽  
Carbon Monoxide ◽  
Co Oxidation ◽  
Microwave Heating ◽  
Oxidation Reaction ◽  
Reaction Order ◽  
Thermal Gradients ◽  
Exponential Factor ◽  
Co Oxidation Reaction ◽  
Kinetics Of

Abstract915 MHz microwave heating has been used to drive the CO oxidation reaction over Pd/Al2O3 without significantly affecting the reaction kinetics. As compared to an identical conventionally heated system, the activation energy, pre-exponential factor, and reaction order with respect to CO were unchanged. Temperature was measured using a thermocouple extrapolation technique. Microwave-induced thermal gradients were found to play a significant role in kinetic observations.

Curing Kinetics of Phenol Formaldehyde Resin Modified with Sodium Silicate

2012 ◽  
Vol 184-185 ◽  
pp. 1471-1479
Author(s):  
Jin Sun ◽  
Xiao Feng Zhu ◽  
Xiao Bo Wang ◽  
Rui Hang Lin ◽  
Zhen Zhong Gao
Keyword(s):  
Activation Energy ◽  
Sodium Silicate ◽  
Reaction Order ◽  
Phenol Formaldehyde ◽  
Curing Kinetics ◽  
Curing Temperature ◽  
Formaldehyde Resin ◽  
Exponential Factor ◽  
Curing Reaction ◽  
Kinetics Of

The curing kinetics of PF resin modified with sodium silicate had been investigated by differential scanning calorimetry (DSC). The kinetic analysis was performed at heating rates of 5, 10, 15, and 20°C/min，respectively. The kinetic parameters such as reaction order and activation energy were solved by Kissinger and Crane equation. The relationship between curing temperature and heating rate was also investigated. The activation energy and the curing reaction order，which were obtained by kinetic calculation, are 83.00kJ/mol and 0.917, respectively. The curing reaction kinetics equations were built by the obtained best curing temperature, reaction order, pre-exponential factor and reaction rate constant.

Kinetics of Rubber-Modified Nylon 6

2014 ◽  
Vol 887-888 ◽  
pp. 951-954
Author(s):  
Hong Kai Zhao ◽  
Hong Li Wang
Keyword(s):  
Activation Energy ◽  
Reaction Order ◽  
Styrene Butadiene Rubber ◽  
Butadiene Rubber ◽  
Exponential Factor ◽  
First Order ◽  
Adiabatic Approach ◽  
Research Findings ◽  
Styrene Butadiene ◽  
Kinetics Of

Kinetic parameters are calculated based on the reactive temperature rise curve measured by adiabatic approach at the temperature of 145 to 160 °C with the catalytic system of NaOH and acyl caprolactam End-capped butadiene-acrylonitrile rubber (CHTBN) or styrene-butadiene rubber (CHTBS). The reaction order is first order, the activation energy is between 72.91−73.16 kJ∙mol−1 and the pre-exponential factor is between 3.22×1011− 3.38×1011 mol1−n∙s−1 in the system of CHTBN/NaOH. While in CHTBS/NaOH, the reaction order is between 1.23-1.34, the activation energy is between 85.55－86.88 kJ∙mol−1 and the pre-exponential factor is between 4.52×1011−5.0 9×1011 mol1−n∙s−1. The adiabatic reaction kinetic model of caprolactam anion was constructed based on the existing research findings, by which the polymerizing reaction is simulated. The coincidence between the simulation results and the experimental data revealed that the model is reasonable and correct.

Thermal and kinetic behaviors of corn stover and polyethylene in catalytic co-pyrolysis

BioResources ◽  
2018 ◽  
Vol 13 (2) ◽  
pp. 4102-4117
Author(s):  
Shaoqing Wang ◽  
Xiaona Lin ◽  
Zhihe Li ◽  
Weiming Yi ◽  
Xueyuan Bai
Keyword(s):  
Activation Energy ◽  
Corn Stover ◽  
Compensation Effect ◽  
Kinetic Studies ◽  
Order Reaction ◽  
Kinetic Compensation Effect ◽  
Exponential Factor ◽  
First Order ◽  
Thermogravimetric Data ◽  
Kinetics Of

Thermal decomposition characteristics and kinetics of high-density polyethylene (HDPE), corn stover (CS), and their blended mixture (1:1 w/w ratio) during non-catalytic and catalytic co-pyrolysis were studied via thermogravimetric analysis (TGA). The results indicated synergetic interactions between the biomass and the plastics during co-pyrolysis as measured by weight loss (ΔW); this effect was attributed to radical interactions during co-pyrolysis. The pyrolysis catalysts with higher nickel loadings (5%, 10%, and 15%) appreciably diminished the solid residue. Kinetic studies indicated that the pyrolysis was a first-order reaction based on the fitted thermogravimetric data. The activation energy (E) and pre-exponential factor (A) ranged between 26.13 kJ/mol to 392.67 kJ/mol and between 156.24 min-1 to 9.19 x 1023 min-1, respectively. There was a kinetic compensation effect (KCE) observed among the two kinetic parameters. The activation energy (E) decreased for each pyrolysis stage with the presence of a catalyst. The results indicated that catalytic co-pyrolysis could provide great potential for reducing the pyrolysis energy input.

Mechanisms and kinetics of initial pyrolysis and combustion reactions of 1,1-diamino-2,2-dinitroethylene from density functional tight-binding molecular dynamics simulations

2019 ◽  
Vol 97 (11) ◽  
pp. 795-804 ◽  
Author(s):  
Dong Xiang ◽  
Weihua Zhu
Keyword(s):  
Activation Energy ◽  
Molecular Dynamics ◽  
Density Functional ◽  
Tight Binding ◽  
Combustion Process ◽  
Exponential Factor ◽  
Three Stages ◽  
Dynamics Simulations ◽  
Combustion Processes ◽  
Kinetics Of

The density functional tight-binding molecular dynamics approach was used to study the mechanisms and kinetics of initial pyrolysis and combustion reactions of isolated and multi-molecular FOX-7. Based on the thermal cleavage of bridge bonds, the pyrolysis process of FOX-7 can be divided into three stages. However, the combustion process can be divided into five decomposition stages, which is much more complex than the pyrolysis reactions. The vibrations in the mean temperature contain nodes signifying the formation of new products and thereby the transitions between the various stages in the pyrolysis and combustion processes. Activation energy and pre-exponential factor for the pyrolysis and combustion reactions of FOX-7 were obtained from the kinetic analysis. It is found that the activation energy of its pyrolysis and combustion reactions are very low, making both take place fast. Our simulations provide the first atomic-level look at the full dynamics of the complicated pyrolysis and combustion process of FOX-7.

Kinetics and Activation Parameters for the Alkaline Aqueous Rearrangement of Trichorfon [O,O-Dimethyl-(2,2,2-Trichloro-1-Hydroxyethyl) Phosphonate] to Dichlorvos [O,O-Dimethyl-O-(2,2-Dichloroethenyl)Phosphate]

2001 ◽  
Vol 36 (3) ◽  
pp. 589-604 ◽  
Author(s):  
Julian M. Dust ◽  
Christopher S. Warren
Keyword(s):  
Activation Energy ◽  
High Pressure ◽  
Activation Parameters ◽  
Base Catalysis ◽  
Rearrangement Product ◽  
Exponential Factor ◽  
First Order ◽  
Pseudo First Order ◽  
Order Plot ◽  
Kinetics Of

Abstract The kinetics of the alkaline rearrangement of O,O-dimethyl-(2,2,2-trichloro-1- hydroxyethyl)phosphonate, (trichlorfon, 1), the active insecticidal component in such formulations as Dylox, was followed at 25±0.5°C by high pressure liquid chromatography (UV-vis detector, 210 nm). The rearrangement product, O,Odimethyl- O-(2,2-dichloroethenyl)phosphate (dichlorovos, 2), which is a more potent biocide than trichlorfon, undergoes further reaction, and the kinetics, consequently, cannot be treated by a standard pseudo-first-order plot. A two-point van't Hoff (initial rates) method was used to obtain pseudo-first-order rate constants (kѱ) at 25, 35 and 45°C: 2.6 × 10-6, 7.4 × 10-6 and 2.5 × 10-5 s-1, respectively. Arrhenius treatment of this data gave an activation energy (Ea) of 88 kJ·mol-1 with a pre-exponential factor (A) of 5.5 × 109 s-1. Kinetic trials at pH 8.0 using phosphate and tris buffer systems show no buffer catalysis in this reaction and indicate that the rearrangement is subject to specific base catalysis. Estimates are reported for pseudo-first-order half-lives for trichlorfon at pH 8.0 for environmental conditions in aqueous systems in the Corner Brook region of western Newfoundland, part of the site of a recent trichlorfon aerial spray program.

scholarly journals The kinetics of the extraction of caffeine from guarana seed under the action of ultrasonic field with simultaneous cooling

2019 ◽  
Vol 9 (1) ◽  
pp. 26-36 ◽  
Author(s):  
Biljana Koturevic ◽  
Borivoj Adnadjevic ◽  
Jelena Jovanovic
Keyword(s):  
Activation Energy ◽  
Kinetic Parameters ◽  
Reaction System ◽  
Ultrasonic Field ◽  
Conventional Heating ◽  
Isothermal Kinetics ◽  
Correlation Relationship ◽  
Exponential Factor ◽  
Caffeine Extraction ◽  
Kinetics Of

AbstractThe kinetics of isothermal extraction of caffeine from guarana seed under the action of ultrasonic field with simultaneous cooling (UESC) was investigated. The isothermal kinetics curves were measured at temperatures range T = 17-58°C. Using the model-fitting method it was determined that the kinetics of caffeine extraction can be described by a theoretical Jander three-dimensional diffusional model. The values of the rate constant were calculated for different temperatures, as well as the kinetic parameters (activation energy (Ea) and pre-exponential factor (lnA)). Based on the results obtained, it is concluded that the rate constants of caffeine extraction under UESC are about 2 times higher in comparison to the values obtained for the extraction in the conditions of conventional heating (CH). The activation energy of the caffeine extraction under the UESC $\left( E_{\text{a}}\,^{\text{UESC}}=19.4\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right)$is lower than the values are for CH $\left( E_{\text{a}}\,^{\text{CH}}=21.8\,\text{kJ}\cdot \text{mo}{{\text{l}}^{-1}} \right).$Energy consumption for UESC is four times lower than for CH conditions. It is shown that there is a linear correlation relationship between kinetic parameters obtained for UESC and CH conditions. The changes in the values of kinetic parameters are explained by the model of selective transfer of energy from the reaction system to the reactant molecules.

Macro Kinetics of N-Phosphonomethyliminodiacetic Acid Catalytic Oxidation

2012 ◽  
Vol 455-456 ◽  
pp. 872-879 ◽  
Author(s):  
Yan Bao ◽  
Jia Wu ◽  
Xiao Ping Hu
Keyword(s):  
Activation Energy ◽  
Kinetic Model ◽  
Measured Data ◽  
Second Step ◽  
Oxidizing Agent ◽  
Dissolved Oxygen Concentration ◽  
Exponential Factor ◽  
In Series ◽  
Kinetics Of ◽  
Made In

The oxidation of N-phosphonomethyliminodiacetic acid (PMIDA) to prepare glyphosate (PMG) over active carbon was investigated. Experiments were carried out with O2 as the oxidizing agent in a 150-mL autoclave made in stainless steel, with reaction temperature ranging from 323.15 to 353.25K and the pressure from 0.12 to 0.40 MPa. The macro kinetic model of the reactions in series was developed, and the pre-exponential factor and activation energy were estimated from the measured data in experiments. The influence of dissolved oxygen concentration was also considered in this macro kinetic model. The results indicated that the two step reactions are all one-order to reactant (PMIDA or PMG) and 0.3 or 0.07 to O2 respectively. The active energy was 12.98kJ/mol for the first step reaction and 10.87kJ/mol for the second step reaction.

scholarly journals Kinetic study of wood pyrolysis in presence of metal halides

2014 ◽  
Vol 12 (12) ◽  
pp. 1294-1303 ◽  
Author(s):  
Vladimir Beliy ◽  
Elena Udoratina
Keyword(s):  
Activation Energy ◽  
Lewis Acids ◽  
Alkaline Earth ◽  
Reaction Order ◽  
Earth Metal ◽  
Inorganic Salts ◽  
Alkaline Earth Metal ◽  
Metal Halides ◽  
Wood Pyrolysis ◽  
Kinetics Of

AbstractThe purpose of this work was to study the kinetics of wood pyrolysis in the presence of inorganic salts, representatives of classes of alkali and alkaline earth metal halides (NaCl, KCl, KBr, CaCl2, BaCl2·2H2O) and Lewis acids (AlCl3·6H2O, FeCl3·6H2O, CuCl2, CuBr2, ZnCl2·1.5H2O, NiCl2·6H2O, SnCl2·2H2O) using TG-DSC. The activity of these catalysts was estimated by the temperature of the beginning of pyrolysis, charcoal yield and kinetic parameters, such as energy of activation and reaction order. Using the Lewis acids as catalysts for pyrolysis leads to a decrease in the temperature of the process beginning and the activation energy. In the presence of other catalysts activation energy does not significantly change. The increase of a seeming reaction order in the presence of Lewis acids possibly is a consequence of complication of the thermodestruction mechanism, with the appearance of new parallel competing stages.

scholarly journals Thermal Analysis On The Kinetics Of Magnesium-Aluminum Layered Double Hydroxides In Different Heating Rates

2015 ◽  
Vol 60 (2) ◽  
pp. 1357-1359 ◽  
Author(s):  
Y. Hongbo ◽  
C. Meiling ◽  
W. Xu ◽  
G. Hong
Keyword(s):  
Activation Energy ◽  
Thermal Analysis ◽  
Layered Double Hydroxides ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
Exponential Factor ◽  
Thermal Kinetic Parameters ◽  
Double Hydroxides ◽  
Kinetics Of ◽  
Dsc Curves

Abstract The thermal decomposition of magnesium-aluminum layered double hydroxides (LDHs) was investigated by thermogravimetry analysis and differential scanning calorimetry (DSC) methods in argon environment. The influence of heating rates (including 2.5, 5, 10, 15 and 20K/min) on the thermal behavior of LDHs was revealed. By the methods of Kissinger and Flynn-Wall-Ozawa, the thermal kinetic parameters of activation energy and pre-exponential factor for the exothermic processes under non-isothermal conditions were calculated using the analysis of corresponding DSC curves.

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