Kinetic and Thermodynamic Analysis of Thermal Decomposition of Deodar (Cedrus Deodara) Saw Dust and Rice Husk as Potential Feedstock for Pyrolysis

2018 ◽  
Vol 17 (1) ◽  
Author(s):  
Tanveer Rasool ◽  
Vimal Chandra Srivastava ◽  
M. N. S. Khan
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Rice Husk ◽  
Nitrogen Atmosphere ◽  
Waste Biomass ◽  
Pyrolysis Kinetics ◽  
Cedrus Deodara ◽  
Saw Dust ◽  
Biomass Materials

Abstract A comparative study on thermal analysis of two waste biomass materials of Kashmir namely deodar (Cedrus deodara) saw dust (DSD) and rice husk (RH), was carried out at different heating rates of 10, 25, 50 and 100 °C min−1 in air and nitrogen atmospheres. The onset, peak and burnout temperatures and rates of decomposition of components were determined and compared to understand the combustion and pyrolysis kinetics of selected biomass materials using iso-conversional Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) models. The kinetic parameters calculated were in turn used to calculate the changes in thermodynamic parameters, the enthalpy (ΔH), the Gibbs free energy (ΔG) and the entropy (ΔS). The physicochemical characterisation was carried out by elemental analyser and FTIR spectroscopy. The average activation energy values for RH were found to be 107.6 and 101.2 kJ mol−1 in air atmosphere and 85.5 and 92.1 kJ mol−1 in nitrogen atmosphere based on KAS and OFW models, respectively. The activation energy for DSD on the other hand was found to be 89.9 and 95.3 kJ mol−1 in air, 179.2 and 180.6 kJ mol−1 under nitrogen atmosphere based on KAS and OFW models, respectively. The heating values of the two biomasses (~ 10 to16 MJ kg−1) and Gibbs free energy values (between 165 to 176 kJ mol−1) indicate that the selected biomass can not only prove to be potential feedstock for pyrolysis but also can become a useful source of energy and chemicals.

Thermogravimetric Analysis of Different Biomass Materials and the Primary Biomass Components

2012 ◽  
Vol 260-261 ◽  
pp. 187-191
Author(s):  
Ya Bo Li ◽  
Xu Ming Zhang ◽  
Lei Qiang Zhao ◽  
Qiang Lu ◽  
Chang Qing Dong
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Combustion Process ◽  
Nitrogen Atmosphere ◽  
Pyrolysis Kinetics ◽  
High Activation ◽  
High Activation Energy ◽  
Pyrolysis Characteristics ◽  
Biomass Components ◽  
Biomass Materials

Thermogravimetric analysis (TGA) was employed to study the pyrolysis and combustion characteristics of three primary biomass components (cellulose, xylan and lignin) and seven different biomass materials under both of nitrogen and air atmosphere. Based on the experimental results, the pyrolysis and combustion kinetics were calculated. The results indicated that the three primary biomass components exhibited different decomposition characteristics and pyrolysis kinetics. Xylan was the least thermal stable component, while the lignin would form much more solid residues than the cellulose and xylan under the nitrogen atmosphere. Moreover, the pyrolytic devolatilization process of the cellulose had high activation energy, so was the char combustion process of the lignin. The seven biomass materials showed similar pyrolysis characteristics, and poplar wood exhibited high activation energy values in both of pyrolysis and combustion processes.

Thermogravimetric Analysis of Raw and Demineralized Biomass Materials

2013 ◽  
Vol 291-294 ◽  
pp. 307-311
Author(s):  
Wen Yan Li ◽  
Zhi Bo Zhang ◽  
Lei Qiang Zhao ◽  
Qiang Lu
Keyword(s):  
Activation Energy ◽  
Thermogravimetric Analysis ◽  
Loss Rate ◽  
Nitrogen Atmosphere ◽  
Poplar Wood ◽  
Pyrolysis Kinetics ◽  
Pine Wood ◽  
Pyrolysis Characteristics ◽  
Biomass Materials ◽  
Maximum Weight Loss

Thermogravimetric analysis (TGA) was employed to study the pyrolysis characteristics of two biomass materials (poplar and pine wood) and their demineralized samples under nitrogen atmosphere. Based on the experimental results, the pyrolysis kinetics were calculated. The results indicated that the starting and ending time of devolatilization were delayed after the demineralization of the biomass. For all the materials, the temperature of the maximum weight loss rate occurred at around 390°C, while the maximum values increased a little after demineralization. The pine wood was more difficult to decompose than the poplar wood, due to its high activation energy values. In addition, after demineralization, the activation energy values of the pine wood decreased, while the values of the poplar wood were not significantly changed.

scholarly journals Kinetics and thermodynamic properties related to the drying of 'Cabacinha' pepper fruits

2016 ◽  
Vol 20 (2) ◽  
pp. 174-180 ◽  
Author(s):  
Hellismar W. da Silva ◽  
Renato S. Rodovalho ◽  
Marya F. Velasco ◽  
Camila F. Silva ◽  
Luís S. R. Vale
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Properties ◽  
Gibbs Free Energy ◽  
Removal Rate ◽  
Effective Diffusion ◽  
Drying Time ◽  
Three Samples ◽  
Different Temperatures

ABSTRACT The objective of this study was to determine and model the drying kinetics of 'Cabacinha' pepper fruits at different temperatures of the drying air, as well as obtain the thermodynamic properties involved in the drying process of the product. Drying was carried out under controlled conductions of temperature (60, 70, 80, 90 and 100 °C) using three samples of 130 g of fruit, which were weighed periodically until constant mass. The experimental data were adjusted to different mathematical models often used in the representation of fruit drying. Effective diffusion coefficients, calculated from the mathematical model of liquid diffusion, were used to obtain activation energy, enthalpy, entropy and Gibbs free energy. The Midilli model showed the best fit to the experimental data of drying of 'Cabacinha' pepper fruits. The increase in drying temperature promoted an increase in water removal rate, effective diffusion coefficient and Gibbs free energy, besides a reduction in fruit drying time and in the values of entropy and enthalpy. The activation energy for the drying of pepper fruits was 36.09 kJ mol-1.

scholarly journals Investigation of the pyrolysis characteristics and kinetics of oil-palm solid waste by using Coats–Redfern method

2019 ◽  
Vol 38 (1) ◽  
pp. 298-309
Author(s):  
Fredy Surahmanto ◽  
Harwin Saptoadi ◽  
Hary Sulistyo ◽  
Tri A Rohmat
Keyword(s):  
Activation Energy ◽  
Solid Waste ◽  
Oil Palm ◽  
Frequency Factor ◽  
Nitrogen Atmosphere ◽  
Empty Fruit Bunch ◽  
Pyrolysis Kinetics ◽  
Pyrolysis Characteristics ◽  
Kinetics Of

The pyrolysis kinetics of oil-palm solid waste was investigated by performing experiments on its individual components, including empty fruit bunch, fibre, shell, as well as the blends by using a simultaneous thermogravimetric analyser at a heating rate of 10°C/min under nitrogen atmosphere and setting up from initial temperature of 30°C to a final temperature of 550°C. The results revealed that the activation energy and frequency factor values of empty fruit bunch, fibre, and shell are 7.58–63.25 kJ/mol and 8.045E-02–4.054E + 04 s−1, 10.45–50.76 kJ/mol and 3.639E-01–5.129E + 03 s−1, 9.46–55.64 kJ/mol and 2.753E-01–9.268E + 03, respectively. Whereas, the corresponding values for empty fruit bunch–fibre, empty fruit bunch–shell, fibre–shell, empty fruit bunch–fibre–shell are 2.97–38.35 kJ/mol and 1.123E-02–1.326E + 02 s−1, 7.95–40.12 kJ/mol and 9.26E-02–2.101E + 02 s−1, 9.14–50.17 kJ/mol and 1.249E-01–2.25E + 03 s−1, 8.35–45.69 kJ/mol and 1.344E + 01–4.23E + 05 s−1, respectively. It was found that the activation energy and frequency factor values of the blends were dominantly due to the role of the components with a synergistic effect occurred during pyrolysis.

Stress Versus Temperature Dependence of Activation Energies for Creep

1992 ◽  
Vol 114 (1) ◽  
pp. 46-50 ◽  
Author(s):  
A. D. Freed ◽  
S. V. Raj ◽  
K. P. Walker
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Elevated Temperatures ◽  
Lattice Diffusion ◽  
Dislocation Climb ◽  
Temperature Dependent ◽  
Dislocation Glide ◽  
Controlling Mechanism ◽  
Stress Dependent

The activation energy for creep at low stresses and elevated temperatures is associated with lattice diffusion, where the rate controlling mechanism for deformation is dislocation climb. At higher stresses and intermediate temperatures, the rate controlling mechanism changes from dislocation climb to obstacle-controlled dislocation glide. Along with this change in deformation mechanism occurs a change in the activation energy. When the rate controlling mechanism for deformation is obstacle-controlled dislocation glide, it is shown that a temperature-dependent Gibbs free energy does better than a stress-dependent Gibbs free energy in correlating steady-state creep data for both copper and LiF-22mol percent CaF2 hypereutectic salt.

scholarly journals Enzymatic Kinetic Issues and Controversies Surrounding Gibbs Free Energy of Activation and Arrhenius Activation Energy

2020 ◽  
pp. 1-13
Author(s):  
Ikechukwu I. Udema ◽  
Abraham Olalere Onigbinde
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Equilibrium Constant ◽  
Gibbs Free Energy ◽  
Theoretical Research ◽  
Energy Of Activation ◽  
Arrhenius Activation Energy ◽  
Free Energy Of Activation ◽  
Different Temperatures ◽  
The Difference

Background: The equation of the difference between reverse and forward Gibbs free energy of activation (ΔΔGES#) reflects Michaelis-Menten constant (KM) in both directions; this may not be applicable to all enzymes even if the reverse reaction is speculatively Michaelian. Arrhenius activation energy, Ea and (Ea - ΔGES#)/RT) are considered = ΔGES# and KM respectively. The equations are considered unlikely. Objectives: The objectives of this research are: 1) To derive what is considered as an appropriate equation for the determination of the difference in ΔGES# between the reverse and forward directions, 2) calculate the difference between the reverse and total forward ΔGES#, and 3) show reasons why Ea ≠ ΔGES#  in all cases. Methods: A major theoretical research and experimentation using Bernfeld method. Results and Discussion: A dimensionless equilibrium constant KES is given. Expectedly, the rate constants were higher at higher temperatures and the free energy of activation with salt was < the Arrhenius activation energy, Ea; ΔΔGES#ranges between 67 - 68 kJ/mol. Conclusion: The equations for the calculation of the difference in free energy of activation (ΔΔGES#) between the forward and reverse directions and a dimensionless equilibrium constant for the formation of enzyme-substrate (ES) were derivable. The large positive value of the ΔΔGES# shows that the forward reaction is not substantially spontaneous; this is due perhaps, to the nature of substrate. The equality of Arrhenius activation energy (Ea) and ΔGES# may not be ruled out completely but it must not always be the case; the presence of additive like salt can increase the magnitude of Ea well above the values of the ΔGES#. A dimensionless equilibrium constant for the net yield of ES seems to be a better alternative than KM. The Ea unlike ΔGES#  requires at least two different temperatures for its calculation.

scholarly journals Some Thermodynamic Properties of White Yam (Dioscorea rotundata) Slices Dehydrated in a Refractance WindowTM Dryer

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Akinjide A Akinola ◽  
Stanley N Ezeorah
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Moisture Content ◽  
Gibbs Free Energy ◽  
Moisture Diffusivity ◽  
Process Conditions ◽  
Dioscorea Rotundata ◽  
History Data ◽  
White Yam ◽  
Different Temperatures

The objective of this study is to estimate the changes in Enthalpy, Entropy and Gibbs Free Energy of yam slices dehydrated at different temperatures using a Refractance WindowTM dryer. Dehydration of 1.5, 3.0 and 4.5 mm thick yam slices, was performed with water temperatures of 65, 75, 85 and 95oC in the flume of a Refractance WindowTM dryer. During the dehydration operations, the moisture-content history data were recorded. For the process conditions considered, the moisture content history data was used to calculate the moisture diffusivity and the activation energy of dehydration of the samples. Subsequently, changes in Enthalpy, , Entropy, , and Gibbs Free Energy, ), were calculated. For the process conditions studied, the changes in, , , and, varied from 20,381.33 to 25,217.05 J.mol-1., -140.69 to -122.29 J.mol-1.K-1.and 67,934.80 to 70,220.15 J.mol-1, respectively. This study is essential as knowledge of these thermodynamic parameters are useful for the optimal design and sizing of preservation dryers for argo-products. Keywords— Enthalpy; Entropy; Gibbs Free Energy; Refractance WindowTM Dryer; Yam 

Thermodynamic Parameters of Nonisothermal Degradation of A New Family of Organometallic Dendrimer with Isoconversional Methods

2021 ◽  
Author(s):  
Ahmad Ali Joraid ◽  
Rawda Mohammad Okasha ◽  
Mahdi A. Al-Maghrabi ◽  
Tarek H. Afifi ◽  
Christian Agatemor ◽  
...  
Keyword(s):  
Activation Energy ◽  
Free Energy ◽  
Thermodynamic Parameters ◽  
Gibbs Free Energy ◽  
Effective Activation Energy ◽  
Isoconversional Methods ◽  
Degradation Process ◽  
Effective Activation ◽  
Exponential Factor ◽  
New Family

Abstract The objective of this work is to obtain the thermodynamic parameters, namely, the changes of enthalpy, Gibbs free energy, and the entropy of two degradation steps observed in three of a new family of organometallic dendrimers. The isoconversional Flynn-Wall-Ozawa (FWO) model was employed to calculate the effective activation energy and pre-exponential factor. The changes of enthalpy and the entropy was consistent with the activation energy, whereas the change of Gibbs free energy remains positive during the entire degradation process, implying that the degradation is non-spontaneous and thus requires external heat supply.

SORPTION OF NICKEL (II) IONS BY CHELATING RESIN WITH IMINODIACETATE FUNCTIONALITY

2019 ◽  
Vol 62 (11) ◽  
pp. 63-71
Author(s):  
Vasilii R. Kurdiumov ◽  
Gennady I. Maltsev ◽  
Konstantin L. Timofeev
Keyword(s):  
Experimental Data ◽  
Activation Energy ◽  
Free Energy ◽  
Gibbs Free Energy ◽  
Sorption Process ◽  
Internal Diffusion ◽  
Static Exchange Capacity ◽  
Activation Process ◽  
Kinetic Curves ◽  
Spontaneous Course

The regularities of sorption of nickel (II) ions from a monocomponent system on macroporous weakly acidic cationite Lewatit MonoPlus TP 207 were studied. Sorption isotherms were obtained. It is shown that the extraction process can be fairly reliably described by Langmuir and Freundlich equations. The static exchange capacity (SEC) of the resin was determined. The SEC dependencies at temperatures of 305 and 328 K during the sorption process were revealed. Integral kinetic curves were obtained. It is defined that the equilibrium concentration of nickel (II) ions is reached about 13 times faster with temperature increase from 305 to 328 K. The experimental data were processed using equations that take into account the influence of external, internal diffusion, "sorbent-sorbate" and "sorbate-sorbate" chemical interactions. It was found that the main limiting stage of sorption of nickel (II) ions is the internal diffusion. The values of external and internal diffusion rate constants at the indicated temperatures were determined. The kinetic curves were processed by pseudo first and pseudo second order models, which satisfactorily describe the experimental data. According to transition-state theory the thermodynamic characteristics of the activation process (activation energy, entropy, enthalpy, and Gibbs free energy) were calculated. Relatively low activation energy indicates the decisive contribution of diffusion in the process of sorption of nickel (II) ions. Positive entropy is the evidence of nickel hydration shells destruction during the sorption process. Positive enthalpy proves an endothermic nature of interaction of nickel (II) ions and ionogenic groups. Negative Gibbs free energy witnesses to spontaneous course of the reaction in the forward direction. For known values of stability constants the contents of nickel ionic forms and SEC’s were calculated in terms of pH value. Nickel extraction from solution increases with the appearance of singly-charged NiOH+ ions in the pH range from 8 to 9.

An Experimental Study of the Coking Process

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Somayeh Ebrahimi ◽  
Jafarsadegh Moghaddas
Keyword(s):  
Activation Energy ◽  
Coke Formation ◽  
Nitrogen Atmosphere ◽  
Fuel Oil ◽  
Effective Parameters ◽  
Pyrolysis Kinetics ◽  
Exponential Factor ◽  
First Order ◽  
First Order Kinetics ◽  
Kinetics Of

The coking process includes two dynamic and isothermal steps. In this process, some factors control the coke formation kinetics. In this research, effects of some important and effective parameters of feed on the quality of petroleum coke were studied. Two hydrocarbon residue feeds; Cracked Fuel Oil (CFO) and Styrene Monomer Tar (SMTAR) were used at 500°C with atmospheric pressure of nitrogen used as an inert gas. Rate of weight loss and gas evolution from these feeds were considered by data of thermal analysis TG (thermogravimetry) and DTG (derivative thermogravimetry). Based on the results, CFO was assigned as the better feed. After selecting better feed, simultaneous thermogravimetry-differential analysis (TG-DTA) was used to study the pyrolysis kinetics of CFO. Samples were heated in a TG-DTA apparatus in nitrogen atmosphere at a temperature range of 37-600°C. The activation energy (Ea) and pre-exponential factor (A) were calculated from the experimental results by using a three stage Arrhenius-type kinetic model and showed that CFO pyrolysis kinetics at temperature ranges 37-285, 320-450 and 467-600°C follows first, second and first order kinetics, respectively. Attentive to temperature increase and reaction progress, activation energy and pre-exponential factor indicated different values at each stage. Also, kinetics of the isothermal step of coke formation was studied during heating of CFO. Samples were reacted in a tube furnace at 450°C and with nitrogen atmosphere. The kinetics of coke formation for petroleum residue was followed by solvent extraction (insolubility in hexane (HI), toluene (TI)) and a development of TI approximate to apparent first order kinetics. The rate constant at this temperature was calculated and it was also observed that the coke formation had been started at a temperature below 450°C.

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