Precision of the Coats and Redfern Method for the Determination of the Activation Energy without Neglecting the Low-Temperature End of the Temperature Integral

Cai, Junmeng; Bi, Lianshan

doi:10.1021/ef8002125

Cited by 52 publications

(20 citation statements)

References 14 publications

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“…The biomass decompositions kinetic model was based on the Coats-Redfern method [29,43,[48][49][50]. The Coats-Redfern method uses the Taylor series applied to the experimental data and limits the numbers of terms in the series.…”

Section: Model-fitting Method: Coats-redfern Methodsmentioning

confidence: 99%

Kinetic Parameters of Nut Shells Pyrolysis

2021

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The European Union created a European Green Deal Program (EGDP). This program aims at a sustainable economy through the transformation of the challenges related to climate and the environment. The main goal of EGDP is climate neutrality by 2050. The increase of alternative biomass residues utilization from various food processing industries and cooperation in the energy and waste management sector is required to meet these expectations. Nut shells are one of the lesser-known, yet promising, materials that can be used as an alternative fuel or a pre-treated product to further applications. However, from a thermal conversion point of view, it is important to know the energy properties and kinetic parameters of the considered biowaste. In this study, the energy and kinetic parameters of walnut, hazelnut, peanut, and pistachio shells were investigated. The results showed that raw nut shells are characterized by useful properties such as higher heating value (HHV) at 17.8–19.7 MJ∙kg−1 and moisture content of 4.32–9.56%. After the thermal treatment of nut shells (torrefaction, pyrolysis), the HHV significantly increased up to ca. 30 MJ∙kg−1. The thermogravimetric analysis (TGA) applying three different heating rates (β; 5, 10, and 20 °C∙min−1) was performed. The kinetic parameters were determined using the isothermal model-fitting method developed by Coats–Redfern. The activation energy (Ea) estimated for β = 5 °C∙min−1, was, e.g., 60.3 kJ∙mol−1∙K−1 for walnut, 59.3 kJ∙mol−1∙K−1 for hazelnut, 53.4 kJ∙mol−1∙K−1 for peanut, and 103.8 kJ∙mol−1∙K−1 for pistachio, respectively. Moreover, the increase in the Ea of nut shells was observed with increasing the β. In addition, significant differences in the kinetic parameters of the biomass residues from the same waste group were observed. Thus, characterization of specific nut shell residues is recommended for improved modeling of thermal processes and designing of bioreactors for thermal waste treatment.

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Section: Model-fitting Method: Coats-redfern Methodsmentioning

confidence: 99%

Kinetic Parameters of Nut Shells Pyrolysis

2021

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“…The samples were analyzed in a sealed sample pan to prevent the loss of water from the formulation during heating. The activation energy was calculated from TGA data according to a reported method 40 …”

Section: Methodsmentioning

confidence: 99%

Preparation of galactomannan based viscosifiers using bifunctional crosslinker: Case studies using 2‐(chloromethyl)oxirane

Dangi

Sharma

Kumar

2021

J of Applied Polymer Sci

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Galactomannans are functionalized biopolymers and possess diverse applications in various fields due to a wide range of inherent properties such as thickening, emulsifying, binding, gelling, film forming, and so on. In the present study, highly viscous solutions were obtained by the treatment of 1,2 galactomannan (Guar gum) with 2-(chloromethyl)oxirane leading to the formation of new 1,3-diethereal linkages of propanetriol (RO CH 2 CHOH CH 2 OR) between the galactomannans backbone. The reaction was studied by varying the amount of 2-(chloromethyl)oxirane in aqueous methanol (methanol: water; 80:20) under alkaline conditions. The 0.5% solution of modified cross-linked galactomannan (MGM) using the least amount of 2-(chloromethyl)oxirane (0.06 Â 10 À3 mol) formed a highly viscous (1031 cps) solution in comparison to native GM (440 cps). Intriguingly, the decreasing amount of 2-(chloromethyl)oxirane led to significant improvement in rheological properties whereas a gradual increase resulted in insoluble products. These observations have so far not been reported for galactomannans. The formation of new 1,3-diethereal linkages (RO CH 2 CHOH CH 2 OR) introduced between the galactomannan backbone was analyzed by NMR (1D and 2D) and FT-IR. Additionally, thermal analysis (TGA and DSC), swelling behavior, the effect of salt, acid, and alkali on MGM were studied. The modified products were resistant to acid, salt, and alkali and can be used for diverse end-use applications.

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“…By plotting ln( m 0 / m [d m /d T ]) against 1/ T , we can calculate the activation energy from the slope of the resulting curve, which is close to a straight line for sublimation/vaporization. − , The second method called the “integral method” relates the activation energy to the mass differential functions in the following manner: , …”

Section: Methodsmentioning

confidence: 99%

An Approach to the Estimation of Adsorption Enthalpies of Polycyclic Aromatic Hydrocarbons on Particle Surfaces

2016

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Current atmospheric models incorporate the values of vaporization enthalpies, ΔHvap, obtained for neat standards, thus disregarding the matrix effects on volatilization. To test the adequacy of this approximation, this study measured enthalpies of vaporization for five polycyclic aromatic hydrocarbons (PAHs) in the form of neat standards (ΔHvap) as well as adsorbed on the surface of silica, graphite, and graphene particles (ΔHvap(eff)), by using simultaneous thermogravimetry-differential scanning calorimetry (TGA-DSC). Measurement of the corresponding activation energy values, Ea(vap) and Ea vap(eff), by TGA using a derivative method was shown to be the most reliable and practical way to assess ΔHvap and ΔHvap(eff). Enthalpies of adsorption (ΔHads) were then calculated from the differences between Ea(vap) and Ea vap(eff), thus paving a way to modeling the solid-gas phase partitioning in atmospheric particulate matter (PM). The PAH adsorption on silica particle surfaces (representing n-π* interactions) resulted in negative values of ΔHads, indicating significant interactions. For graphite particles, positive ΔHads values were obtained; i.e., PAHs did not interact with the particle surface as strongly as observed for PM. PAHs on the surface of graphene particles evaporated in two stages, with the bulk of the mass loss occurring at temperatures lower than those with the neat standard, just as on graphite. Yet, unlike graphite, a small PAH fraction did not evaporate until higher temperatures compared to case of the neat standards and other particle surfaces (37.4-145.7 K), signifying negative, more PM-relevant values of ΔHads, apparently reflecting π-π* interactions and ranging between -7.6 and +32.6 kJ mol(-1), i.e., even larger than for silica, -3.3 to +8.3 kJ mol(-1). Thus, current atmospheric models may underestimate the partitioning of organic species in the particle phase unless matrix adsorption is taken into account.

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Precision of the Coats and Redfern Method for the Determination of the Activation Energy without Neglecting the Low-Temperature End of the Temperature Integral

Cited by 52 publications

References 14 publications

Kinetic Parameters of Nut Shells Pyrolysis

Kinetic Parameters of Nut Shells Pyrolysis

Preparation of galactomannan based viscosifiers using bifunctional crosslinker: Case studies using 2‐(chloromethyl)oxirane

An Approach to the Estimation of Adsorption Enthalpies of Polycyclic Aromatic Hydrocarbons on Particle Surfaces

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