Oxidation kinetics of biodiesel from soybean mixed with synthetic antioxidants BHA, BHT and TBHQ: Determination of activation energy

In this work the kinetics of the thermal decomposition of two ß-diketone lanthanide complexes of the general formula Ln(thd)3phen (where Ln = Nd+3 or Tm+3, thd = 2,2,6,6- tetramethyl-3,5-heptanodione and phen = 1,10-phenantroline) has been studied. The powders were characterized by several techniques. Thermal decomposition of the complexes was studied by non-isothermal thermogravimetry techniques. The kinetic model that best describes the process of the thermal decomposition of the complexes it was determined through the method proposed by Coats-Redfern. The average values the activation energy obtained were 136 and 114 kJ.mol-1 for the complexes Nd(thd)3phen and Tm(thd)3phen, respectively. The kinetic models that best described the thermal decomposition reaction the both complexes were R2. The model R2 indicating that the mechanism is controlled by phase-boundary reaction (cylindrical symmetry) and is defined by the function g(α) = 2[1-(1-a)1/2], indicating a mean reaction order. The values of activation energy suggests the following decreasing order of stability: Nd(thd)3phen > Tm(thd)3phen.

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Torrefaction of Sewage Sludge: Kinetics and Fuel Properties of Biochars

Energies ◽

10.3390/en12030565 ◽

2019 ◽

Vol 12 (3) ◽

pp. 565 ◽

Cited By ~ 24

Author(s):

Jakub Pulka ◽

Piotr Manczarski ◽

Jacek Koziel ◽

Andrzej Białowiec

Keyword(s):

Activation Energy ◽

Sewage Sludge ◽

Thermal Transformation ◽

Fuel Properties ◽

Process Time ◽

Technological Aspect ◽

Heating Value ◽

Valuable Product ◽

Kinetics Of

We propose a ‘Waste to Carbon’ thermal transformation of sewage sludge (SS) via torrefaction to a valuable product (fuel) with a high content of carbon. One important, technological aspect to develop this concept is the determination of activation energy needed for torrefaction. Thus, this research aimed to evaluate the kinetics of SS torrefaction and determine the effects of process temperature on fuel properties of torrefied products (biochars). Torrefaction was performed using high ash content SS at six (200~300 °C) temperatures and 60 min residence (process) time. Mass loss during torrefaction ranged from 10~20%. The resulting activation energy for SS torrefaction was ~12.007 kJ·mol−1. Initial (unprocessed) SS higher heating value (HHV) was 13.5 MJ·kg−1. However, the increase of torrefaction temperature decreased HHV from 13.4 to 3.8 MJ·kg−1. Elemental analysis showed a significant decrease of the H/C ratio that occurred during torrefaction, while the O/C ratio fluctuated with much smaller differences. Although the activation energy was significantly lower compared with lignocellulosic materials, low-temperature SS torrefaction technology could be explored for further SS stabilization and utilization (e.g., dewatering and hygienization).

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Kinetics of Magnetic Relaxation and Determination of Activation Energy in High-$\bf {\mbi T}_{c}$ Superconductors

Japanese Journal of Applied Physics ◽

10.1143/jjap.33.l843 ◽

1994 ◽

Vol 33 (Part 2, No. 6B) ◽

pp. L843-L845

Author(s):

Xiao-Guang Li ◽

Ryu Kobayashi ◽

Yasutoshi Kotaka ◽

Jun-ichi Shimoyama ◽

Kohji Kishio

Keyword(s):

Activation Energy ◽

Magnetic Relaxation ◽

Kinetics Of

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Desorption characteristics and kinetic parameters determination of molecular sieve by thermogravimetric analysis/differential thermogravimetric analysis technique

Adsorption Science & Technology ◽

10.1177/0263617418772665 ◽

2018 ◽

Vol 36 (7-8) ◽

pp. 1389-1404 ◽

Cited By ~ 3

Author(s):

Yalou Guo ◽

Hui Zhang ◽

Yingshu Liu

Keyword(s):

Activation Energy ◽

Thermogravimetric Analysis ◽

Heating Rates ◽

Carrier Gas ◽

Zeolite 13X ◽

Analysis Technique ◽

Desorption Activation Energy ◽

Differential Thermogravimetric Analysis ◽

Kinetics Of

The kinetics of the thermal desorption of CO2 adsorbed on zeolite 13X were obtained using a differential thermogravimetric analyser under two different carrier gas conditions. The varying heating rates were set as 8, 12, 16, and 20 K min−1, respectively. The desorption activation energy of the physisorption sites for this experiment evaluated by an integral method without prediction of the reaction order ranged from 12.15 to 14.12 kJ mol−1 (CO2 as the carrier gas) and 43.32 to 50.42 kJ mol−1 (Ar as the carrier gas), respectively. The desorption activation energy of the chemisorption sites ranged from 57.95 to 58.53 kJ mol−1 (CO2 as the carrier gas) and 74.02 to 79.92 kJ mol−1 (Ar as the carrier gas), respectively.

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Theory of Doping in Studies of Defect Concentration and Transport Properties of Transition Metal Oxides and Sulphides

High Temperature Materials and Processes ◽

10.1515/htmp-2014-0104 ◽

2015 ◽

Vol 34 (5) ◽

Author(s):

Zbigniew Grzesik

Keyword(s):

Transition Metal ◽

Metal Oxides ◽

Transition Metal Oxides ◽

Oxidation Kinetics ◽

Defect Formation ◽

Defect Concentration ◽

Defect Mobility ◽

Enthalpy And Entropy ◽

Kinetics Of

AbstractIn the present paper the theoretical basis and experimental verification of a method, enabling the calculation of defect concentration and their mobility in transition metal oxides and sulphides have been described. The idea of proposed method consists in determination of both these parameters in indirect way, i.e. in studying the influence of aliovalent metallic additions on the oxidation kinetics of a given metal (doping effect). It has been shown that from the results of oxidation kinetics of binary alloys, the enthalpy and entropy of defect formation and their migration can be calculated. These data, in turn, can be used for the calculation of defect concentration and defect mobility in pure, undoped oxides. Such a possibility has been illustrated on the example of nonstoichiometric nickel oxide, Ni

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Determination of Recrystallization Kinetics and Activation Energy of Grain Growth Process of Cu-14Al-4Ni Shape Memory Alloy

MRS Proceedings ◽

10.1557/opl.2015.818 ◽

2015 ◽

Vol 1765 ◽

pp. 127-132 ◽

Cited By ~ 1

Author(s):

Emmanuel P. R. Lima ◽

Pedro C. de Lima ◽

Marcelo Nava

Keyword(s):

Activation Energy ◽

Shape Memory Alloy ◽

Shape Memory ◽

Grain Growth ◽

Growth Process ◽

Treatment Time ◽

Mechanical Tests ◽

A Value ◽

Kinetics Of

ABSTRACTThe non-ferrous shape memory alloys have, normally, two problems that hinder its use in industrial scale: the natural aging and grains growth. The first degrades the memory effect, while the second, observed during the processing of alloy, modifies the temperatures which the transformations occur. Thus, the study of kynetic of recrystallization is important for enabling the control of hardened state in function of treatment time, without causing excessive grain growth. Therefore, the objective of this study is to determine the kinetics of recrystallization of Cu-14Al-4Ni shape memory alloy, based on an empirical law of the formation of Jonhson-Mehl-Avrami, as well as their activation energies for grain growth process according to the empirical Arrhenius law. The alloy was vacuum melted in an induction furnace. After casting, the bulk samples of the alloy were homogenized for 24 hours, solubilized and hot rolled followed by water-quenching to initiate the recrystallization. Then, different samples were annealed at temperatures close to the peak, start and end of the DSC curve. Following the heat treatments, the samples were submitted to mechanical tests and the values of the properties were correlated to the fraction transformed for determination of recrystallization’s kinetic. For the characterization of the grain growth process, analyses in optical microscopy were accomplished and all annealed samples were examined by statistical metallography and the grain sizes were measured. After measurements, the ln[-ln(1-Yrec)] x ln(t) and the ln [D-Do] x 1/T diagrams were plotted to determine the parameters of Jonhson-Mehl-Avrami equation and the activation energy of the process, respectively. The results showed that the equation of the recrystallized fraction follows the empiric law of the formation of Jonhson-Mehl-Avrami for the considered property, as well as, also showed that the alloy Cu-14Al-4Ni is extremely sensitive to temperature variation in which the alloy is treated, having a dual kinetics of grain growth. In the first domain, between 670 and 710°C, the diagram provides a value for the activation energy equal to 39.32 KJ/mol, in the second domain, between 710 and 790°C, the diagram provides a value for the activation energy equal to 9.01 KJ/mol.

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Effect of Tackifier on Thermal Oxidation Kinetics and Effective Storage Time of Raw Natural Rubber

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.898.102 ◽

2014 ◽

Vol 898 ◽

pp. 102-106

Author(s):

Bei Long Zhang ◽

Hong Hai Huang ◽

Wei Yong Deng ◽

Yong Zhou Wang ◽

Li Ding ◽

...

Keyword(s):

Activation Energy ◽

Natural Rubber ◽

Thermal Oxidation ◽

Oxidation Kinetics ◽

Storage Time ◽

Hydrazine Sulfate ◽

Accelerated Storage ◽

Thermal Oxidation Kinetics ◽

Storage Times ◽

Kinetics Of

The thermal oxidation kinetics of natural rubber containing hydrazine dihydrochloride or hydrazine sulfate used as tackifier were studied, and the effective storage time of natural rubber containing tackifier was predicted with a method of heat accelerated storage aging. The results show that the thermal oxidation activation energy of natural rubber containing hydrazine dihydrochloride is 105.6kJ/ mol, being a little higher than that (104.7 kJ/ mol) of the control. The thermal oxidation activation energy of natural rubber containing hydrazine sulfate is 103.1kJ/ mol, being a little lower than that of the control. The effective storage time of natural rubber containing hydrazine dihydrochloride is 13.4 years at 30°C,27.0years at 25°C, and 55.9years at 20°C. The effective storage time of natural rubber containing hydrazine sulfate is 11.6years at 30°C,23.0 at 25°C, and 46.8years at 20°C.The effective storage times of natural rubber containing two tackifiers hydrazine dihydrochloride or hydrazine sulfate are higher than that of the control at the same condition.

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