Kinetic modelling of the thermal oxidation of polyisoprene elastomers. Part 2: Effect of sulfur vulcanization on mass changes and thickness distribution of oxidation products during thermal oxidation

The present study is aimed at kinetic modeling of phenol oxidation using Fentons reagent in a medium suitable for bioremediation of organic pollutants. Batch experiments were conducted to study the effects of H2O2 concentration (29.26 to 146.31 mM), temperature (5 to 35°C), and to compare the oxidation of phenol in a bioremediation medium to that in pure water. The reaction mechanism used for kinetic modeling is based on the intermediate oxidation products identified in this study using LC-MS and ion chromatography. Progress of the chemical oxidation by Fentons reagent was monitored by determining the residual phenol concentration and concentrations of evolved intermediate compounds (catechol and hydroquinone) at regular time intervals. The rate of phenol oxidation and ultimate conversion of phenol were found to increase with increase in hydrogen peroxide concentration. The increase in temperatures has a positive effect on phenol oxidation and the rate of phenol oxidation was found to increase with temperature in the range of 5-35°C. Kinetic parameters, namely rate constants and activation energies for reactions involved, were determined by best-fitting the experimental data to the proposed reaction model. The values of the rate constants for oxidation of phenol and intermediate compounds, k1 (phenol to catechol), k2 (phenol to hydroquinone), k3 (catechol to maleic acid), k4 (hydroquinone to maleic acid) at 25°C were found to be 7.02x10-5±4.63x10-5, 7.22x10-4±6.09x10-4, 1.82x10-4±1.08x10-4, 1.68x10-3±1.29x10-3 L/mM min, respectively.

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Coal oxidation at low temperatures: oxygen consumption, oxidation products, reaction mechanism and kinetic modelling

Progress in Energy and Combustion Science ◽

10.1016/s0360-1285(03)00042-x ◽

2003 ◽

Vol 29 (6) ◽

pp. 487-513 ◽

Cited By ~ 387

Author(s):

Haihui Wang ◽

Bogdan Z. Dlugogorski ◽

Eric M. Kennedy

Keyword(s):

Oxygen Consumption ◽

Reaction Mechanism ◽

Low Temperatures ◽

Kinetic Modelling ◽

Oxidation Products ◽

Coal Oxidation

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Thermal Oxidation Products of Nylon 6 Determined by MALDI-TOF Mass Spectrometry

Macromolecular Rapid Communications ◽

10.1002/1521-3927(20010401)22:7<524::aid-marc524>3.0.co;2-b ◽

2001 ◽

Vol 22 (7) ◽

pp. 524-529 ◽

Cited By ~ 22

Author(s):

Donatella Chionna ◽

Concetto Puglisi ◽

Filippo Samperi ◽

Giorgio Montaudo ◽

Antonio Turturro

Keyword(s):

Mass Spectrometry ◽

Thermal Oxidation ◽

Nylon 6 ◽

Oxidation Products ◽

Maldi Tof Mass Spectrometry ◽

Maldi Tof

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Thermal-Oxidation Stability of Soybean Germ Phytosterols in Different Lipid Matrixes

Molecules ◽

10.3390/molecules25184079 ◽

2020 ◽

Vol 25 (18) ◽

pp. 4079 ◽

Cited By ~ 1

Author(s):

Jingnan Chen ◽

Dami Li ◽

Guiyun Tang ◽

Jinfen Zhou ◽

Wei Liu ◽

...

Keyword(s):

Fatty Acids ◽

Olive Oil ◽

Thermal Oxidation ◽

Loss Rate ◽

Unsaturated Fatty Acids ◽

Oxidation Stability ◽

Oxidation Products ◽

Higher Temperature ◽

The Stability ◽

Thermal Oxidation Stability

The stability of soybean germ phytosterols (SGPs) in different lipid matrixes, including soybean germ oil, olive oil, and lard, was studied at 120, 150, and 180 °C. Results on the loss rate demonstrated that SGPs were most stable in olive oil, followed by soybean germ oil, and lard in a decreasing order. It is most likely that unsaturated fatty acids could oxidize first, compete with consumption of oxygen, and then spare phytosterols from oxidation. The oxidation products of SGPS in non-oil and oil systems were also quantified. The results demonstrated that at relatively lower temperatures (120 and 150 °C), SGPs’ oxidation products were produced the most in the non-oil system, followed by lard, soybean germ oil, and olive oil. This was consistent with the loss rate pattern of SGPs. At a relatively higher temperature of 180 °C, the formation of SGPs’ oxidation products in soybean germ oil was quantitatively the same as that in lard, implying that the temperature became a dominative factor rather than the content of unsaturated fatty acids of lipid matrixes in the oxidation of SGPs.

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Identification of thermal oxidation products of cholesteryl acetate

Journal of Chromatography A ◽

10.1016/s0021-9673(94)89104-4 ◽

1994 ◽

Vol 683 (1) ◽

pp. 75-85 ◽

Cited By ~ 7

Author(s):

Renzo Bortolomeazzi ◽

Lorena Pizzale ◽

Lanfranco S. Conte ◽

Giovanni Lercker

Keyword(s):

Thermal Oxidation ◽

Oxidation Products ◽

Cholesteryl Acetate

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INFLUENCE OF PRODUCT TO BE FRIED TYPE ON THE RATE OF THERMAL OXIDATION OF OILS

Известия вузов. Пищевая технология ◽

10.26297/0579-3009.2021.2-3.13 ◽

2021 ◽

Author(s):

А.В. БОРИСЕВИЧ ◽

Т.И. ЧАЛЫХ

Keyword(s):

Thermal Oxidation ◽

Heating Temperature ◽

Coconut Oil ◽

Oxidation Products ◽

Deep Frying ◽

Chicken Nuggets ◽

Animal Product ◽

Oxidation Inhibitors ◽

Optical Density Index ◽

Optimal Heating

Проведено исследование процесса термического окисления подсолнечного и кокосового масел при 175°С в условиях поточного обжаривания в них картофеля и куриных наггетсов с отбором проб растительного масла через каждый час работы. Для определения количества продуктов окисления был использован метод спектрофотометрии. Установлено, что после 10 ч проведения обжарки исследованные фритюрные масла были пригодны для дальнейшего использования (Е < 15). Показатель оптической плотности кокосового масла независимо от вида обжариваемого в нем продукта в течение всего эксперимента был ниже аналогичного показателя подсолнечного масла. Предложена оптимальная температура нагрева кокосового масла для обжаривания во фритюре – не более 0,9 от температуры точки дымления. Показано более активное накопление вторичных продуктов окисления во фритюрном масле при обжаривании продукта животного происхождения по сравнению с обжариванием продукта растительного происхождения, что можно объяснить наличием в составе картофеля ингибиторов окисления (пероксидаза, каталаза, витамин С). The study of the process of thermal oxidation of sunflower and coconut oils at 175°C under conditions of in-line frying of potatoes and chicken nuggets in them with the sampling of vegetable oil every hour of operation was carried out. To determine the amount of oxidation products the method of spectrophotometry was used. It was found that after 10 hours of roasting, the studied fryer oils were suitable for further use (E < 15). The optical density index of coconut oil, regardless of the type of product fried in it, was lower than that of sunflower oil throughout the experiment. The optimal heating temperature of coconut oil for deep frying is proposed-no more than 0,9 of the temperature of the smoking point. A more active accumulation of secondary oxidation products in deep-frying oil is shown when frying an animal product compared to frying a vegetable product, which can be explained by the presence of oxidation inhibitors (peroxidase, catalase, vitamin C) in the composition of potatoes.

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