Transformation kinetics and mechanism of gibberellic acid with ferrihydrite: Building a novel adsorption-transformation multi-step kinetic model

Chemosphere ◽  
2021 ◽  
pp. 133194
Author(s):  
Li Zhang ◽  
Yajun Sun ◽  
Zhimin Xu ◽  
Fei Liu
Keyword(s):  
Kinetic Model ◽  
Gibberellic Acid ◽  
Kinetics And Mechanism ◽  
Transformation Kinetics

Kinetics and Mechanism of Acid-Catalyzed Decomposition of 1,3-Bis(4-methylphenyl)triazene in Hexane-Organic Acid Medium

1996 ◽  
Vol 61 (3) ◽  
pp. 355-363 ◽  
Author(s):  
Miroslav Ludwig ◽  
Miriam Kabíčková
Keyword(s):  
Kinetic Model ◽  
Organic Acid ◽  
Acid Medium ◽  
Rate Constant ◽  
Fourth Order ◽  
Kinetics And Mechanism ◽  
Acid Catalyzed ◽  
Kinetics Of

The kinetics of acid-catalyzed decomposition of 1,3-bis(4-methylphenyl)triazene have been studied in mixtures of hexane and organic acid of various ratios using acetic, isovaleric, and pivalic acids as the catalysts. In all the cases, a monotonously increasing dependence of the observed rate constant upon mol fraction of the acid has been found. The results obtained are discussed with the help of the classic third- and fourth-order functions by Margules and the respective kinetic model. The main catalyzing particle appears to be the dimer of the respective acid, the reaction probably going via a complex formed by two molecules of acid and one molecule of the triazene.

Kinetics and mechanism of anatase-to-rutile phase transformation in the presence of borosilicate glass

1999 ◽  
Vol 14 (7) ◽  
pp. 2922-2928 ◽  
Author(s):  
Jau-Ho Jean ◽  
Shih-Chun Lin
Keyword(s):  
Phase Transformation ◽  
Borosilicate Glass ◽  
Rutile Phase ◽  
Kinetics And Mechanism ◽  
Avrami Equation ◽  
Two Dimensional ◽  
Transformation Kinetics ◽  
Controlling Mechanism ◽  
Particle Coalescence ◽  
Kinetics Of

The effects of borosilicate glass (BSG) on the kinetics and mechanism of anataseto- rutile phase transformation have been investigated. The displacive anatase-to-rutile phase transformation kinetics of TiO2 were greatly enhanced in the presence of BSG. The transformation kinetics followed the Avrami equation, and the results showed an apparent activation energy of 260–370 kJ/mol, which was close to the bond strength of Ti–O, suggesting a reaction-controlling mechanism. The values of the Avrami exponent were in the range of 1.4–2.3, which could be interpreted as two-dimensional reaction-controlled growth at zero nucleation rate. The rutile particles obtained by the phase transformation were always much larger than the starting anatase powders, which was explained by a mechanism of phase-transformation–induced particle coalescence.

scholarly journals Anaerobic Transformation Kinetics and Mechanism of Steroid Estrogenic Hormones in Dairy Lagoon Water

2012 ◽  
Vol 46 (10) ◽  
pp. 5471-5478 ◽  
Author(s):  
Wei Zheng ◽  
Xiaolin Li ◽  
Scott R. Yates ◽  
Scott A. Bradford
Keyword(s):  
Kinetics And Mechanism ◽  
Transformation Kinetics ◽  
Lagoon Water ◽  
Estrogenic Hormones

scholarly journals Bottom Ash Modification via Sintering Process for Its Use as a Potential Heavy Metal Adsorbent: Sorption Kinetics and Mechanism

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3060
Author(s):  
Young-Kyu Hong ◽  
Jin-Wook Kim ◽  
Hyuck-Soo Kim ◽  
Sang-Phil Lee ◽  
Jae-E. Yang ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Kinetic Model ◽  
Photoelectron Spectroscopy ◽  
Bottom Ash ◽  
Critical Issue ◽  
Sorption Kinetics ◽  
Kinetics And Mechanism ◽  
Order Kinetic ◽  
Order Kinetic Model ◽  
Industrial Byproducts

Heavy metal pollution in the environment is a critical issue, engendering ecosystem deterioration and adverse effects on human health. The main objective of this study was to evaluate heavy metal adsorbents by modifying industrial byproducts. The bottom ash was sintered and evaluated for Cd and Pb sorption. Three adsorbents (bottom ash, sintered bottom ash (SBA), and SBA mixed with microorganisms (SBMA)) were tested to evaluate the sorption kinetics and mechanism using a lab-scale batch experiment. The results showed that the highest sorption efficiency was observed for Cd (98.16%) and Pb (98.41%) with 10% SBA. The pseudo-second-order kinetic model (R2 > 0.99) represented the sorption kinetics better than the pseudo-first-order kinetic model for the SBA and SBMA, indicating that chemical precipitation could be the dominant sorption mechanism. This result is supported by X-ray photoelectron spectroscopy analysis, demonstrating that -OH, -CO3, -O, and -S complexation was formed at the surface of the sintered materials as Cd(OH)2 and CdCO3 for Cd and PbO, and PbS for Pb. Overall, SBA could be utilized for heavy metal sorption. Further research is necessary to enhance the sorption capacity and longevity of modified industrial byproducts.

scholarly journals Mechanical Behavior of Multi-Phase Steels Comprising Retained Austenite

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 498
Author(s):  
Emin Semih Perdahcıoğlu ◽  
Hubert J. M. Geijselaers
Keyword(s):  
Kinetic Model ◽  
Retained Austenite ◽  
Mean Field ◽  
High Strength ◽  
Transformation Kinetics ◽  
Analytical Estimate ◽  
Dp Steel ◽  
Thermodynamic Driving Force ◽  
The Stability ◽  
Multi Phase

The retained austenite (RA) in advanced high-strength steel (AHSS) grades, such as dual-phase (DP) steels, plays an important role on their formability. Thanks to the transformation-induced plasticity (TRIP) effect that occurs during the mechanically induced transformation of RA into martensite, additional ductility is obtained. Martensite has a higher flow stress than austenite; hence, the transformation results in an apparent hardening, which is beneficial for the stability of deformation. The stability of RA at a given temperature strongly depends on its carbon content, which, in AHSS, is not uniform but distributed. The aim of this study is to build a model that predicts the transformation as well as TRIP in a DP steel grade with RA. A physics-based kinetic model is presented that captures the transformation of retained austenite based on the thermodynamic driving force of the applied stress. A direct analytical estimate of transformation plasticity is provided, which is consistent with the kinetic model. Transformation kinetics is incorporated in a self-consistent, mean-field homogenization-based constitutive model. Finally, an indication of the effect of transformation of retained austenite on formability is given.

Kinetics and mechanism of the chromium(vi) catalyzed decomposition of hypochlorous acid at elevated temperature and high ionic strength

2018 ◽  
Vol 47 (11) ◽  
pp. 3831-3840 ◽  
Author(s):  
József Kalmár ◽  
Mária Szabó ◽  
Nina Simic ◽  
István Fábián
Keyword(s):  
Elevated Temperature ◽  
Ionic Strength ◽  
Kinetic Model ◽  
Hypochlorous Acid ◽  
Active Form ◽  
High Ionic Strength ◽  
Kinetics And Mechanism ◽  
Chromium Vi ◽  
Catalytically Active ◽  
Detailed Kinetic Model

The decomposition of hypochlorous acid was studied under industrially relevant conditions (6.0 M NaClO3, 80 °C). Chromium(vi) catalyzes the decomposition and the catalytically active form is CrO42−. A detailed kinetic model is proposed for the process.

scholarly journals An in situ EDXRD kinetic and mechanistic study of the hydrothermal crystallization of TiO2 nanoparticles from nitric acid peptized sol–gel

CrystEngComm ◽  
2015 ◽  
Vol 17 (9) ◽  
pp. 2013-2020 ◽  
Author(s):  
Mohammad Rehan ◽  
Girish M. Kale ◽  
Xiaojun Lai
Keyword(s):  
Nitric Acid ◽  
Kinetic Model ◽  
Reaction Kinetics ◽  
Tio2 Nanoparticles ◽  
Sol Gel ◽  
Kinetics And Mechanism ◽  
Mechanistic Study ◽  
Hydrothermal Crystallization ◽  
Diffusion Controlled

In situ EDXRD has been used to probe the reaction kinetics and mechanism of the hydrothermal crystallization of TiO2 nanoparticles. The process was found to involve a diffusion-controlled mechanism based on the Avrami–Erofe'ev kinetic model.

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